Chapter 5. Porcupines, Coyotes, Deer, Bats
Porcupines-Erethizon
dorsatum
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Description. Most porcupines are tropical; however, Erethizon dorsatum has adapted to
survive in extreme cold conditions, up to the tree line in far northern areas. The
porcupine is a rodent. It has black to brownish-yellow fur and strong, short
legs. It has hairless soles on its feet that help it climb trees. It has a
round body, small ears and a small head. The most recognizable feature of the
porcupine is its quills.
Adult
porcupines have approximately 30,000 large quills covering the dorsal and tail
regions. More slender and elongated quills blanket the shoulders and sides of
the body. Quills are hidden under long, white-tipped guard hairs until animals
are agitated or in a warning posture. Guard hairs serve to protect the animals
from precipitation and snow while tactilely sensing the surrounding
environment. These hairs are black, brown, or chestnut in color, 6 to10 inches
long, and give porcupines a fluffy appearance.
Adult Porcupine.
Image en Wikipedia.
Porcupines have several adaptations for climbing
trees to reach food. Both front and hind feet have extremely long claws
protruding from the toes that can be inserted into tree bark crevices to aid in
climbing. The four claws on the front feet and five claws on the hind feet are
used as a grooming comb. They are long enough to extend through the quill layer
to the skin. Front claws are used to manipulate foods, such as fruits and small
branches, and to pull tree branches into feeding range. Front and hind footpads
resemble rubber with a pebble-like texture from structures called tuberosities,
which are used to increase friction against the tree trunk. While climbing
stiff, backward-pointing bristles on the underside of the tail are pressed
against tree bark. This provides an anchor and prevents downward sliding.
An
additional adaptation for climbing is the absence of an external male penis and
a membrane covering the female vagina. These characteristics make it difficult
to distinguish males from females by casual observation. Depending on the areas
and season the body weight of porcupines can vary
M
ale porcupines may average 13 to 25 pounds while females averaged 11 to 16
pounds. Weight varies by season since porcupines store a considerable amount of
body fat at the beginning of winter and lose all stored fat by spring. The
average length of a mature adult varies from 25½ to 36½ inches. Weight
variation from young to mature adults varies from 7¾ to 39 pounds. Tail
lengths, which are critical for defense from predators, range from5¾ to 11¾ inches.
Distribution. Porcupines are found throughout Canada and the
western United States. Originally from
South America, porcupines are an ecologically adaptable species, spreading as
far north as Alaska. They are found in deciduous forests, low deserts such as
the Mojave in California, high desert regions of the Great Plains, and
coniferous forests throughout the western states. Porcupine presence is
detected by identifying pellets or scats beneath feeding or resting trees.
Another distinguishing feature of porcupine presence is discarded “niptwigs” on
the ground underneath a feeding tree. Nip twigs are terminal twigs stripped of
leaf blades and discarded. Niptwigs often are eaten by deer and other mammals.
Seasonal Activity. .
Porcupine dens are used for temporary shelter from rain, snow, and
insects or for protection during winter. The two types of dens, pre-winter and
winter are different in structure and location. Pre-winter dens are typically
located close to roosting or feeding sites and consist primarily of hollow
trees. Winter dens are generally rock crevices in steep-sloped areas and
located away from these sites. A string of below freezing temperature days
stimulates porcupines to enter a permanent den.
In winter dens porcupines commonly come out to feed at night. If rock crevices are not available, caves,
live hollow trees, hollow logs, human outbuildings, and thickly branched crowns
of evergreens are also used. Some animals
remain outside all year, especially in areas where evergreens and crevices are
not present. Hemlock and Douglas fir are
convenient food source. Porcupines do not use bedding or nesting material in
the den but, instead, prefer a clean dry floor. Large accumulations of feces
occur since dens are used year after year. In moist, temperate climates, feces
are decomposed by mites; however, in dry, arid climates, accumulated feces form
into an extremely hard concrete-like mass.
A series of days where temperatures are above freezing and decreased
snow pack typically stimulate emergence from winter dens.
Porcupines
are nocturnal animals and active all year. However, much time is spent resting
in trees called “rest trees.” Use of a den or rest tree is evident by
the presence of broken quills, recent scats, and the pungent odor of urine. Rest
trees are a critical component of their habitat, even during adverse winter
weather conditions. These trees may be deciduous or conifer species but a
common characteristic is a dense crown that provides cover and protection from
predators.
Porcupine in a Rest Tree. Image Courtesy en Wikipedia.
During
spring and early summer, porcupines gorge on a variety plants in preparation
for the winter: however, in deciduous forests, porcupines do not need ground
vegetation to compliment their diet, although some highly preferred foods, such
as raspberry leaves, are readily consumed if available
Spring
feeding on ground forage is controlled by snow cover. When there is no snow
cover, porcupines feed exclusively on whatever ground vegetation is available
and edible. Dietary items include grasses, flowers, dandelions, flowering
herbs, and various other vegetation. Porcupines in western Douglas fir-juniper
forests feed on ground vegetation in spring and return to a diet of tree bark
and evergreen needles in the fall. . Southwest porcupines will eat shrubs such
as gooseberry, plums, chokecherry, buffaloberry, elder, black haw, raspberry
canes, and buckbrush. Herbaceous plants in their diets include geranium,
lupine, cinquefoil, wyethia, and lousewart. Porcupines gain weight rapidly in
the spring, feeding on nitrogen-rich forage. High nitrogen intake and changing
climate trigger winter fur molting. The molting process is completed in a
matter of days, leaving only the guard hairs, quills, and tail bristles. This
rich spring diet has other consequences—a loss of sodium and subsequent desire
for salt.
Porcupines
alter their feeding behavior in response to seasonal plant species changes and
food resource availability. During summer, ground vegetation (skunk cabbage,
clover, lupines) comprises up to 85 percent of the porcupine diet. The
remaining 15 percent is tree-gathered material, primarily bark. These
herbaceous animals feed primarily on inner tree bark, twigs, and leaves with a
preference for Ponderosa pine, aspen, willow, and cottonwoods. Porcupines
prefer trees with a thin, smooth bark as opposed to a thicker bark. Hence, young trees with thin palatable barks
are often targets for foraging porcupines.
During
fall, porcupines substantially increase their intake of tree-gathered materials
for forage to approximately 72 percent. Ground vegetation becomes less prevalent due to declining nutrient
content and lower availability because of snow cover. Porcupines in deciduous
forests commonly remain within a small home-range area all year long due to
abundant food sources. However, in western mountainous regions porcupines have
much larger home range and wander extensively to fulfill nutritional
requirements.
In
winter, porcupines feed exclusively on tree materials such as tree bark, twigs,
buds, and evergreen needles. Specific tree species used for winter food vary
between vegetative community types.
Porcupines cannot travel easily through snow. Therefore, winter activity
and feeding can be as much as 90 percent less than spring and summer activity.
Winter home-range is considerably smaller than summer home-range areas.
Porcupines
find salt in salt-enriched soils, plants, road salt, wood, and various other
items. These animals have been reported eating mud in salty-soil areas and
wading in ponds to consume various plants, such as yellow water lily and
aquatic liverwort, which have high salt concentrations. Rock salt, left over
from salting winter roads to improve travel, is another source. Plywood,
human-handled wood posts and timbers, fresh animal bones, old shoes and boots,
paint, and the outer bark of trees contain sources of salt as well. Any object
impregnated with urine also attracts porcupines because of the salt content.
General Biology. Prior to
engaging in a fight, porcupines will warn their attackers by displaying their quills,
omitting threatening vocalizations, and producing an offensive odor. Porcupines
use their quills as a last resort for defense.
Teeth
clattering also warns potential predators. Porcupines deliberately shiver their
bodies and simultaneously close their jaws, causing the incisors and cheek
teeth to vibrate against one another. If all three warnings are ignored,
porcupines use their quills when attacked. Quill tips have tiny fish-hook barbs
that make removal difficult. The upper tail surface has short black quills that
are much more dangerous than the longer back and neck quills. The porcupine
cannot shoot its quills. When a predator approaches, the porcupine will turn
its back, raise the quills and lash out at the threat with its tail. If the
porcupine hits an animal with its quills, the quills become embedded in the
animal. Body heat makes the barbs expand and they become even more deeply
embedded in the animal's skin. If an animal is hit in a vital place it may die.
There are documented cases where a quill has perforated a man’s intestine and
caused death. Infections seldom occur from embedded quills since they have
antibiotic properties.
Porcupines
are very vocal during mating season. Males often fight over females. The male
performs an elaborate dance and sprays urine over the head of the female.
Mating typically occurs in the fall and seven months later the female gives
birth to a single baby. When the baby is born, its quills are soft. They harden
about an hour after birth. The baby is begins to forage for food after only a
couple of days.
The
quills, developed at birth, are not injurious to the mother because of
protection from the placental sac and the main moisture content of new quills.
Newborn porcupines are fully developed at birth, usually weighing about one
pound. They grow rapidly, doubling their weight in about two weeks. Although
young porcupines can flick their tails within an hour after birth, their best
defense is hiding. Young porcupines are essentially odorless, making it
difficult for predators to locate them. In addition, defecation is stimulated
by the mother during this early period, and the droppings are eaten to
eliminate any fecal odor, which may attract predators. When old enough to
climb, young porcupines spend more time in trees as evidenced by the
accumulation of tiny droppings under trees. Porcupines normally give birth to
only one offspring each year. The female nurses the young from a pair of
nipples located under the armpits and another pair on the abdomen. The female sits
upright on her haunches and tail, allowing the newborn access to her quill-free
abdomen. Nursing lasts approximately four months, following the 9 month
gestation period.
Adult
females do not wander far from the offspring during the first 6 weeks after
birth. Young porcupines can climb small sapling-size trees, but these smaller
trees are often difficult for adults to climb. Therefore, mother and infant
meet only at night on the ground. Generally, though, adult females sleep in a
resting tree during the day, with the baby hidden on the ground in hollow bases
of trees, rock crevices, under fallen tree trunks, and in slash piles.
As
young porcupines mature, the separation distance between mothers and their
offspring increases during the day due to greater travel distances. At night,
however, mothers always return to the young from distances as far away as a
half mile. While accompanying their mothers, young porcupines learn locations
of food trees, dens, shelters, and hiding places. Weaning occurs at the end of
the mating season in late fall. Male offspring may remain within the mother’s
home range in the fall, but females generally leave. Young porcupines spend
their first winter alone and reach sexual maturity
during
the third year after birth. Males commonly mate with more than one female to
ensure species perpetuity. This is important since reproductive rates are low.
Porcupines
have generally low mortality rates, with an average life span of seven to eight
years. Common causes of mortality are disease, winter stress, injury, and human
predation. Scabies, caused by the mite Sarcoptes scabiei, causes high
mortality among porcupines; other parasites include lice, ticks, tapeworms, and
nematodes. In severe winters, porcupines die from prolonged sub-zero temperatures
and heavy snow pack, which limits access to food material. In some cases,
porcupines injure themselves falling out of trees.
Porcupines
have few natural predators, although fishers are probably the most efficient at
killing porcupines. Fishers can overturn a porcupine easily, exposing the
unquilled ventral side to a fatal attack. However, fishers are often fatally
injured during this encounter. Other natural predators include mountain lions,
bobcats, horned owls, coyotes, fox, black bear and marten.
Adult Fisher.
Economic Impact. Economic losses from porcupines feeding on forest
plantations, ornamental trees, and fruit orchards and damage to human articles
containing salts can be considerable.
They usually are tolerated except where high-value ornamental plantings,
commercial timber, nursery stock, or orchard trees are damaged by girdling,
basal gnawing, or branch clipping. Often, tree diameter growth is restricted or
young saplings are killed from their feeding.
Most
porcupine feeding on mature trees occurs in the crown where preference for
leaves, terminal twigs, and young bark prevails
This type of feeding activity does not kill the tree, but it causes
lateral branching in various directions where terminal branches are removed.
Successive years of pruning terminal branches result in short growth form with
several twisted, odd-shaped limbs. Trees that develop an “eerie” growth form
due to porcupine impact are commonly called “witch trees.” Trees most
susceptible to mortality are young saplings where porcupine feeding on the
ground results in basal girdling. Porcupine feeding activities can influence
the structure and plant species composition of the forest, especially near
their winter dens. Since porcupines feed close to winter dens and occupy the
same dens each year, trees in these areas sustain heavy impact year after year.
Although in some situations, this impact may result in long-term ecological
diversification of forest vegetation. In this scenario, trees preferred for feeding
are suppressed, allowing non-preferred tree species to compete for existing
soil and water resources. Eventually, this results in a more diverse plant
community structure.
In
addition, feeding in the canopy of mature trees reduces canopy cover, permits
more light penetration to the forest floor, and stimulates more herbaceous
understory plant production. A more diverse understory plant community can
provide better habitat conditions for wildlife species such as ruffed grouse,
snowshoe hare, white-tailed deer, moose, morning warbler, yellowthroat, and a
variety of other songbirds and small mammals. Porcupines also provide another
benefit to forest birds by providing shelter and nest sites in hollow tree
trunks. Porcupine feeding activities may expose the tree’s heartwood area where
sap and soft inner plant tissue attract insects used by birds as a food source.
One
study claims that a single porcupine could destroy approximately $6,000 worth
of timber during its lifetime. Researchers claimed the majority of damage was
due to girdling of Ponderosa pine seedlings, with lesser damage to lodge pole
pine, white fir, Douglas fir, and spruce. Timber companies frequently cite
porcupines for extensive damage to commercial plantations but rarely describe
the location and size of the damaged area, methods used to estimate damage
losses, and considerations of other potential forest animals as perpetrators of
tree damage. Before blaming porcupines, other potential causes of damage (such
as deer, rabbits, drought, fungi, insects, excessive soil temperatures, and
competition from invasive plants) should be considered.
Other economic losses from porcupines include
damage to ornamental trees planted around summer cabins, vacation homes, and
rural homesteads. In some areas, damage to fruit and nut orchard plantations by
porcupines can be extensive. There also have been reports of porcupines
damaging corn, small grains, and alfalfa fields.
Legal Status. Many states
have adopted protective measures for porcupines because of their vulnerability
to human harvesting. Others classify porcupines
as a “predatory animal” and can be taken without a license in any manner and at
any time of the year.
Prevention and Management Techniques.
Prevention. Generally, any forest management technique that
perpetuates closed canopy tree stands reduces porcupine populations. In closed
canopy tree stands there is limited understory herbaceous vegetation, resulting
in reduced food for porcupines. These conditions restrict porcupine numbers by
reducing reproductive potential, encourage development of larger home-range
areas, and increase winter mortality from stress-related causes due to
nutritional deficiencies. Recent theories suggest practices that open canopy
cover, such as prescribed burning and timber harvest, result in more favorable
habitat conditions and attract natural porcupine predators. Increased predator
densities may suppress porcupine populations as well.
Fencing. Fencing is a preventive measure with limited
application due to the high cost of materials. However, fencing can be
cost-effective where potential economic losses may be great such as in research
areas, commercial tree plantations, and fruit or nut orchards. Fencing porcupines from small tree plantings, orchards and gardens can
be done with some small alterations. Porcupines can climb fences, but an
overhanging wire strip around the top of the fence at a 65 degree angle to the
upright wire will discourage them. A combination fence of 18 inch poultry wire
topped with a smooth electric wire 1 1/2 “ above will deter animals. A 4 to 6 inch high electric fence painted with molasses has also
been shown to be barriers around orchards, plantations and gardens. Individual
trees can be enclosed with 30” wire baskets or bands of aluminum flashing
Repellents. There is a capsaicin-based hot sauce repellent (Miller’s Hot Sauce)
that is registered to protect plastic tubing from porcupines. Another
repellent, Thiram, which is registered for squirrels and rabbits, may also
repel porcupines. Thiram is sprayed or painted on plants to prevent damage.
Exterior plywood painted with wood preservative will sometime deter porcupines
from gnawing. Exterior plywood can be coated with common wood
preservatives to deter chewing, but this is not 100 percent effective. A better
solution is to provide
an alternative salt source, since chewing on plywood is done mainly to satisfy
a salt craving. A short picket fence made from salt-impregnated wood sticks
offers a good “salt lick” for porcupines.
Biological Options. One researcher in the Southwest
suggested that porcupines inflict more damage to trees when livestock
overgrazing removes preferred summer forage. Assuming this relationship exists,
light livestock grazing may be used as a tool to stimulate more herbaceous
forage production (used by porcupines as a food source), therefore relieving
porcupine damage to trees in the area.
Enhancing
natural predator numbers is another biological control option to consider. Over
time, unrestricted trapping and excessive killing of natural predators, such as
the fisher, coyote, and mountain lion, may have promoted higher porcupine
numbers. Recently, fishers have been released in California, Idaho, Oregon,
Montana, Michigan, Wisconsin, New York, and Vermont to re-establish original
numbers. These releases were not conducted to control porcupine populations
specifically; however, Michigan researchers report that fishers appear to be
impacting porcupine numbers.
Live Trapping. Live trapping
porcupines is easy and effective for individual animals damaging gardens, small
orchards, or ornamental trees. Commercial cage traps or homemade box traps
baited with salt-soaked materials work well in damage areas. Once trapped,
animals should be relocated at least 25 miles away in suitable habitat to
prevent their return. Porcupines also can be caught by inverting a garbage can
over them, sliding the lid under the can, and turning the can upright. A cone
constructed of wire fencing material and inverted over the animal works as
well. A piece of plywood can be slid under the wire cone before inverting the
cone. With any live trapping method, avoid the tail area and use thick rubber
gloves to handle the animal.
Direct Control.
Shooting. Non-lethal
techniques to control problem porcupines are always the preferred approach.
But, in some cases of extensive damage or where non-lethal techniques are
ineffective on individual problem animals, lethal control techniques must be
considered.
Porcupines are
considered non-game animals and are not protected. However, this unassuming and
mild mannered creature should be controlled by other non-lethal methods before
resorting to shooting. Lethal control should be limited to individual animals
causing the damage.
However,
shooting is effective when justified. Hunting during late-spring and summer is
an effective time for harvesting animals feeding on herbaceous ground
vegetation, irrigated crops, and orchard trees. Hunting during the fall and
early winter may also reduce colonization; however, this usually has less
impact on porcupine populations than summer shooting.
Poisoning. There are no
registered toxicants to use in controlling porcupines.
Trapping. Porcupines are easy to live trap in commercial wire cage traps, which
are readily available at feed, hardware and garden supply stores. The best bait
is strips of plywood or other absorbent woods, cloths, or sponges soaked in
salt water. Where legal No. 2 or
3 steel leg hold traps are effective or No.
220 or 330 Conibear body gripping traps
baited with salted objects are equally effective. Traps should be placed near the entrance
of active dens or along well-used trails.
Coyotes
Identification. Coyotes are
readily recognizable to the average individual. The coyote is a medium-sized
member of the dog family that also includes wolves and foxes. With its pointed
ears, slender muzzle, and drooping bushy tail, the coyote often resembles a
German shepherd or collie. Coyotes are usually a grayish brown with reddish
tinges behind the ears and around the face, but coloration can vary from a
silver-gray to black. Most have dark or black guard hairs over their back and
tail. The tail usually has a black tip.
Eyes are a striking yellow, with large dark pupils, rather than brown
like many dogs. While coyotes are capable of interbreeding with domestic dogs,
hybrids (known as coydogs) are generally rare. Most adults weigh between 25 and
35 lbs., although their heavy coats often make them appear larger. There have
been suggestions that urban coyotes are larger than rural coyotes, but we have
seen no evidence of this.
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A Coyote. Image Courtesy Justin Johnsom, Wikipedia
Range. Historically, coyotes
were found in the western states. Over the last 50 years they have extended
their range to cover most of North America. Coyotes live in almost any habitat
in California from arid deserts to coastal regions. They are not as common in
densely forested areas or planted agricultural situations due to decreased food
sources. Coyotes are both transient and territorial dependent upon food
resources, breeding time, and pup rearing. Where food is readily available
territories are smaller. Territories can range 15 square miles to 1 to 3 square
miles, and even one quarter of a square mile. Packs consist of up to 10
individuals. A dominant pair may share its area with juvenile offspring.
Coyotes are not as social as wolves and can live successfully as solitary
individuals.
Habitat . Many
references indicate that coyotes were originally found in relatively open
habitats, particularly the grasslands and sparsely wooded areas of the western
United States. Coyotes have adapted to and now exist in virtually every type of
habitat, arctic to tropic, in North America. Coyotes live in deserts, swamps,
tundra, grasslands, brush, dense forests, from below sea level to high mountain
ranges, and at all intermediate altitudes. High densities of coyotes also
appear in the suburbs of Los Angeles, Orange County, Pasadena, Phoenix, and
other western cities.
Food Habits. Coyotes are quite omnivorous feeding on
a wide variety of fruit, vegetable, meat, other food products. Rabbits and
ground squirrels top the list of their dietary components. Carrion, rodents,
ungulates (usually fawns), insects, as well as livestock and poultry, are also
consumed. Coyotes readily eat fruits such as watermelons, berries, and other
vegetative matter when they are available. In some areas coyotes feed on human
refuse at dump sites and readily capture and consumes pets (cats and dogs).
Coyotes prefer prey that is the easiest to secure
including the young or wild animals, inexperienced animals, as well as old,
sick, or weakened individuals. With domestic animals, coyotes are capable of
catching and killing healthy, young, and in some instances adult prey. They are very cunning, something selecting
their prey based on behavioral characteristics. For example, strong healthy
lambs are often taken from a flock by even though smaller, weaker lambs are also
present. Usually, the stronger lamb is on the periphery and is more active,
making it more prone to attack than a weaker lamb that is at the center of the
flock and relatively immobile.
Coyotes are presently the most abundant
livestock predators in western North America, causing the majority of sheep, goat and cattle losses. For example: according to the National
Agricultural Statistics Service, coyotes
were responsible for 60.5% of the 224,000 sheep deaths that were attributed to
predation in 2004.[50] However
the total number of sheep deaths in 2004 comprised only 2.22% of the total
sheep and lamb population in the United States. According to the National
Agricultural Statistics Service USDA
report, "All sheep and lamb inventory in the United States on July 1,
2005, totaled 7.80 million head, 2 percent above July 1, 2004. Breeding sheep inventory at 4.66 million head on July 1, 2005 was 2
percent above July 1, 2004. By virtue of the fact that coyote populations are
typically many times greater and more widely distributed than those of wolves,
coyotes cause more overall predation losses. However, an Idaho census taken in
2005 showed that individual coyotes were one-twentieth as likely to attack
livestock as individual wolves.
Coyotes will typically bite the throat just
behind the jaw and below the ear when attacking adult sheep or goats, with
death commonly resulting from suffocation. Blood loss is usually a secondary
cause of death. Calves and heavily-fleeced sheep are killed by attacking the
flanks or hind-quarters, causing shock and blood loss. When attacking smaller
prey, such as young lambs, the kill is made by biting the skull and spinal
regions, causing massive tissue damage. Small or young prey may be completely
carried off, leaving only blood as evidence of a kill. Coyotes will usually
leave the hide and most of the skeleton of larger animals relatively intact,
unless food is scarce, in which case they may leave only the largest bones.
Scattered bits of wool, skin and other parts are characteristic where coyotes
feed extensively on larger carcasses.
Coyote predation can usually be distinguished
from dog or coydog predation by the fact that coyotes partially consume their
victims. Tracks are also an important factor in distinguishing coyote from dog
predation. Coyote tracks tend to be more oval-shaped and compact than those of
domestic dogs, plus, claw marks are less prominent and the tracks tend to
follow a straight line more closely than those of dogs. With the exception of sight hounds, most dogs of similar weight to coyotes have a slightly
shorter stride. Coyote kills
can be distinguished from wolf kills by the fact that there is less damage to
the underlying tissues. Also, coyote scats tend to be smaller than wolf scats.
Coyotes are often attracted to dog food and
animals that are small enough to appear as prey. Items like garbage, pet food
and sometimes feeding stations for birds and squirrels will attract coyotes
into backyards. Approximately 3 to 5 pets attacked by coyotes are brought into
the Animal Urgent Care hospital of south Orange County (California) each week,
the majority of which are dogs, since cats typically do not survive the attacks. Scat analysis
collected near Claremont,
California revealed that coyotes
relied heavily on pets as a food source in winter and spring. At one location in Southern California,
coyotes began relying on a colony of feral cats as a food source. Over time, the coyotes killed most of the
cats, and then continued to eat the cat food placed daily at the colony site by
citizens who were maintaining the cat colony. Coyotes attack smaller
or similar sized dogs, and they have been known to attack even large, powerful
breeds like the Rottweiler in exceptional cases. Dogs larger than coyotes are
generally able to drive them off, and have been known to kill coyotes. Smaller
breeds are more likely to suffer injury or death.
Other factors come into play as far as when coyote
predation typically occurs. With livestock coyote predation on livestock
typically more commonly occurs during early spring and summer rather than the
winter. Livestock is usually under more intensive management during winter,
either in feedlots or in pastures. This
typically equates to nearby human activity, a situation that some coyotes attempt
to avoid. Also coyotes, as with most
predators, produce their young in the spring and raise them through the summer,
a process that demands increased nutritional input. This increased demand
corresponds to the time when young sheep or beef calves are on pastures or
rangeland and are most vulnerable to attack. Coyote predation also may increase
during fall when young coyotes disperse from their home ranges and establish
new territories.
General Biology, Reproduction, and Behavior. Coyotes are mostly
nocturnal and or crepuscular (early morning hours). This is especially true in urban situations
or other situations where human activity occurs, and during hot summer months.
Where there is minimal human interference and during cool weather, they may be
active throughout the day.
The coyote is one of the few wild animals whose
vocalizations are commonly heard. At night coyotes both howl (a high quavering
cry) and emit a series of short, high-pitched yips. Howls are used to keep in
touch with other coyotes in the area. Sometimes, when it is first heard, the
listener may experience a tingling fear of primitive danger, but to the
seasoned outdoorsman, the howl of the coyote is truly a song of the West.
Howling also is an
announcement that “I am here and this is my area. Other males are invited to
stay away but females are welcome to follow the sound of my voice. Please
answer and let me know where you are so we don't have any unwanted conflicts.”Yelping is a celebration or criticism
within a small group of coyotes. This is often heard during play among pups or
young anim. The bark is thought to be a threat display when a coyote is
protecting a den or a kill. Huffing
- is usually used for calling pups without making a great deal of noise.
Coyotes rest and sleep in sheltered areas but do not
generally use dens except when raising young. They possess excellent eyesight
and hearing with a keen sense of smell. They are very tough and hardy with
excellent recuperative powers. They are
quite fleet of foot having been measured
at speeds of up to 40 miles per hour and can sustain slower speeds for several
miles.
As with dogs distemper, hepatitis, parvo virus, and
mange are among the most common coyote diseases. Rabies and tularemia also
occur and may be transmitted to other animals and humans. They are susceptible
numerous parasites including mites, ticks, fleas, worms, and flukes. Mortality
is highest during the first year of life, and few survive for more than 10 to
12 years in the wild. Human activity is often the greatest single cause of
coyote mortality.
At the beginning of the mating season in
January, several lone male coyotes may gather around a female to court her, but
she will form a relationship with only one of them. The male and female desert
coyote may travel together before mating in January or February.
The female bears one litter of 3 to 9 puppies a
year, usually in April or May when food is abundant. The gestation period is
from 63 to 65 days. The pups are born blind in a natal den, but their eyes open
after about 14 days and they emerge from the den a few days later. They suckle
for 5 to 7 weeks, and start eating semi-solid food after 3 weeks. While the
male helps support the family with regurgitated food, the mother does not allow
him to come all the way into the den. The pups live and play in the den until
they are 6 to 10 weeks old, when the mother starts taking them out hunting in a
group. The family gradually disbands, and by fall the pups are usually hunting
alone. Within a year, they go their own way, staking out their own territory, marked
with the scent of their urine.
As
noted earlier, coyotes are capable of hybridizing with dogs and wolves, but
this is unlikely. When interbreeding with domestic dogs occurs survival of the
offspring is low. Typically, coy-dogs’ breeding cycles do not correspond to
coyotes’ thus further breeding with coyotes is unlikely even though coy-dogs
are able to reproduce.
Coyote dens are found in steep banks, rock crevices,
sinkholes, and underbrush, as well as in open areas. Usually their dens are in
areas selected for protective concealment. Den sites are typically located less
than a mile (km) from water, but may occasionally be much farther away. Coyotes
will often dig out and enlarge holes dug by smaller burrowing animals. Dens
vary from a few feet to 50 feet and may have several openings.
Both adult male and female coyotes hunt and bring food
to their young for several weeks. Other adults associated with the denning pair
may also help in feeding and caring for the young. Coyotes commonly hunt as
singles or pairs; extensive travel is common in their hunting forays. They will
hunt in the same area regularly, however, if food is plentiful. They
occasionally bury food remains for later use.
Pups begin emerging from their den by 3 weeks of
age, and within 2 months they follow adults to large prey or carrion. Pups
normally are weaned by 6 weeks of age and frequently are moved to larger
quarters such as dense brush patches and/or sinkholes along water courses. The
adults and pups usually remain together until late summer or fall when pups
become independent. Occasionally pups are found in groups until the breeding season
begins. The U.S.
government routinely shoots,
poisons, traps and kills 90,000 coyotes each year to protect livestock.
Coyotes in Urban
Situations.
Despite being extensively hunted, the coyote is
one of the few medium-to-large-sized animals that have enlarged its range since
human encroachment began. It originally ranged primarily in the western half of
North America, but it has adapted readily to the changes caused by human occupation and, since the early 19th century, has been
steadily and dramatically extending its range. Sightings now commonly occur in Michigan, Illinois, Wisconsin, California, Oregon, New England, New Jersey, Ohio, and eastern Canada. Coyotes have been seen in nearly every continental U.S.
state, and also Alaska. Coyotes have moved into most of the areas of North America formerly occupied by wolves, and are often observed foraging in suburban garbage bins.
Coyotes also thrive in suburban settings and
even some urban ones. A study by wildlife ecologists at Ohio
State University yielded some surprising
findings in this regard. Researchers studied coyote populations in Chicago over a seven-year period (2000–2007), proposing that
coyotes have adapted well to living in densely populated urban environments
while avoiding contact with humans. They found, among other things, that urban
coyotes tend to live longer than their rural counterparts, kill rodents and small pets, and live anywhere from parks to industrial areas. The researchers estimate that there are up to 2,000
coyotes living in "the greater Chicago area" and that this
circumstance may well apply to many other urban landscapes in North America. In
Washington DC's Rock Creek Park, coyotes den and raise their young, scavenge
road kill, and hunt rodents. "I don't see it as a bad thing for a
park," the assigned National
Park Service biologist told a
reporter for Smithsonian Magazine ". I see it as good for keeping
animal populations in control, like the squirrels and the mice."
As a testament to the
coyote's habitat adaptability, a coyote nicknamed "Hal" made his
way to New
York City's Central Park in March 2006, wandering about the park for at least two
days before being captured by officials. New York's parks commissioner Adrian
Benepe noted this coyote had to be very "adventurous" and
"curious" to get so far into the city. In February 2010, up to three coyotes were
spotted on the Columbia University campus, and another coyote sighting occurred
in Central Park. An incident also occurred in April 2007 in the Chicago Loop district, where a coyote, later nicknamed
"Adrian", quietly entered a Quizno's restaurant during the lunch hours; it was later captured
and released at a wildlife rehab center near Barrington,
Illinois.
Coyote
attacks on humans are uncommon and rarely cause serious injuries, due to the
relatively small size of the coyote. However, coyote attacks on humans have
increased since 1998 in the state of California. Data from USDA Wildlife
Services, the California Department of Fish & Game, and other sources show
that while 41 attacks occurred during the period of 1988-1997, 48 attacks were
verified from 1998 through 2003. The majority of these incidents occurred in
Southern California near the suburban-wildland interface.
Due to an absence of
harassment by residents, urban coyotes lose their natural fear of humans, which
is further worsened by people intentionally feeding coyotes. In such
situations, some coyotes have begun to act aggressively toward humans, chasing
joggers and bicyclists, confronting people walking their dogs, and stalking
small children. Like wolves, non-rabid coyotes usually target small children, mostly under the age
of 10, though some adults have been bitten.
There are only two
recorded fatalities in North America from coyote attacks.[ In 1981
in Glendale,
California, a coyote attacked
toddler Kelly
Keen, who was rescued by her
father, but died in surgery due to blood loss and a broken neck. In October 2009, Taylor Mitchell, a 19-year-old folk singer on tour, died from injuries
sustained in an attack by a pair of coyotes while hiking in the Skyline Trail of the Cape
Breton Highlands National Park in Nova Scotia, Canada. Recent studies have shown however that the large
northeastern coyotes responsible for this attack may in fact be coyote-wolf
hybrids due to absorption of wolves when coyotes moved into eastern North
America.
Humans increase the likelihood of
conflicts with coyotes by deliberately or inadvertently feeding the animals,
whether by handouts or by providing access to food sources such as garbage, pet
food or livestock carcasses. When people provide food, coyotes quickly lose their
natural fear of humans and become increasingly aggressive. They also become
dependent on the easy food source people provide. Once a coyote stops hunting
on its own and loses its fear of people, it becomes dangerous and may attack
without warning.
Prevention is the best tool for minimizing conflicts
with coyotes and other wildlife. To prevent conflicts with coyotes, the
following management strategies around neighborhood communities should be
encouraged.
Don’t
leave small children unattended where coyotes are frequently seen or heard. If there are coyote sightings in an area,
children should be prepared for a possible encounter. The reasons why coyotes
live in an area (habitat/food source species adaptability) and what should be
done if one approaches (don’t run, be as big, mean, and loud as possible). By
shouting a set phrase such as “go away coyote” when a coyote is encountered,
children will inform nearby adults of the coyote’s presence as opposed to a
general scream.
Never
feed coyotes. Coyotes that
are fed by people often lose their fear of humans and develop a territorial
attitude that may lead to aggressive behavior.
If in a homeowner’s association or neighborhood watch, the subject
should be discussed during one of the meetings.
Don’t
give coyotes access to garbage. Garbage can lids should be kept on tight by securing
them with rope, chain, bungee cords, or weights or use garbage cans with clamps
or other mechanisms that hold lids on. To prevent tipping, secure the side
handles to metal or wooden stakes driven into the ground or keep cans in
tight-fitting bins, a shed, or a garage.
Prevent
access to fruit and compost. Coyotes are
omnivorous and will readily eat many types of food including fruit. Keep fruit
trees fenced, or pick up fruit that falls to the ground. Keep compost piles
within a fenced area or securely covered. Cover new compost material with soil
or lime to prevent it from smelling. Never include animal matter in compost; it
attracts coyotes. If burying food scraps, cover them with at least 12 inches of
soil, and don’t leave any garbage above ground in the area.
Feed
dogs and cats indoors. If pets are feed outdoors pets do so in
the morning or at midday, and water bowls, leftovers and spilled food should d
be removed well before dark every day.
Don’t
feed feral cats (domestic cats gone wild). Coyotes prey on these cats as well as
any food provided for them. Prevent the buildup of feeder foods under bird
feeders. Coyotes will eat bird food and are attracted to the many birds and
rodents that come to feeders.
Keep
dogs and cats indoors, especially from dusk to dawn. If left
outside at night in an unprotected area, cats and small to mid-size dogs may be
killed by coyotes. Pets can be easy prey for coyotes. Being raised by humans
leaves them unsuspecting once they leave the safety of a home. If a dog or cat
is lost to a coyote, neighbors should be notified. Once a coyote finds easy
prey it will continually hunt in the area.
Modify
the landscape around children’s play areas. Shrubs and
trees should be pruned several feet above ground level so coyotes can’t hide in them. Keep deterrents nearby
in times of increased sightings. An old hockey stick, broom, or a pile of
stones near the play area can help prepare children for an encounter and will
remind them of effective encounter behavior.
Build a
coyote-proof fence. Coyotes don’t leap fences in a single bound but, like
domestic dogs, they grip the top with their front paws and kick themselves
upward and over with the back legs. Their tendency to climb will depend on the
individual animal and its motivation. A 5-foot woven-wire fence with extenders
facing outward at the top of each post should prevent coyotes from climbing
over.
However, all coyotes are excellent diggers, and an
effective fence needs to extend at least 8 inches below the surface, or have a
galvanized-wire apron that extends out from the fence at least 15 inches.
Electric fences can also keep coyotes out of an
enclosed area. Such a fence doesn’t need to be as high as a woven-wire fence
because a coyote’s first instinct will be to pass through the wires instead of
jumping over them. Digging under electric fences usually doesn’t occur if the
bottom wire is electrified.
Enclose
poultry (chickens, ducks, and turkeys) in a secure outdoor pen and house. Coyotes will eat poultry and their eggs if they can
get to them. Note: Other killers
of poultry include foxes, skunks, raccoons, feral cats, dogs, bobcats,
opossums, weasels, hawks, and owls.
To prevent coyotes from accessing birds in their night
roosts, equip poultry houses with well-fitted doors and secure locking
mechanisms. To prevent them from trying to go under the fence, stake the bottom
of the fence flush to the ground, or line the bottom of the fence with bricks,
fence posts, or similar items.
To prevent coyotes and other animals from accessing
poultry during the day, completely enclose outdoor pens with 1-inch chicken
wire placed over a sturdy wooden framework.
Coyotes in Rural and Agricultural Situations
Damage and Damage Identification. Coyotes
feeding can be very destructive to livestock, poultry, and crops. In many
cities of the United States they have become a major problem as their numbers
have increased tremendously and their predation on pets has increased
correspondingly. They sometimes are a threat to public health and safety when
they frequent airport runways and residential areas, and act as carriers of
rabies and other diseases as discussed above.
In rural areas, the primary concern regarding coyotes is predation on
livestock, mainly sheep and lambs. Predation will be the focus of the following
discussion.
Coyote attacking
sheep. Image courtesy of USDA, Animal
Plant Health Inspection Service,
Wildlife Research Center
In 1999, the National Agricultural Statistics Service
(NASS) surveyed producers and found that coyotes killed an estimated 165,800
sheep and lambs nationwide worth a total of $9.6 million. Feral dogs and
foxes accounted for an additional 49,400 lamb and sheep deaths worth $3.5
million. In addition, coyotes, feral dogs, and foxes killed approximately
36,000 goats worth more than $1.8 million.
Coyotes and feral dogs also feed on cattle and
calves. The NASS survey found that coyotes killed an estimated 95,000
cattle and calves worth $31.8 million in 2000. Feral dogs killed 26,000
cattle and calves worth $9.5 million.
In addition, coyotes, foxes, and feral dogs kill thousands of chickens,
turkeys, ducks, geese, and other birds every year.
Since coyotes frequently scavenge on livestock
carcasses, the mere presence of coyote tracks or droppings near a carcass does
not necessarily indicate that predation has occurred; however, there are other
signs that may be present that can help in this determination. These may
include scrapes or drag marks on the ground, broken vegetation, or blood in
various places around the site. The quantity of sheep or calf remains left
after a kill vary widely depending on how recently the kill was made, the size
of the animal killed, the weather, and the number and species of predators that
fed on the animal.
One key in determining if an animal was killed by a
predator is the presence or absence of subcutaneous bleeding at the point of
attack. The point is that if a dead animal is bitten by a predator bleeding
does not occur. Talon punctures from large birds of prey will also cause hemorrhage,
but the location of these is usually at the top of the head, neck, or back. If
enough of the carcass remains the skin around the neck and head can be removed
to examine for hemorrhaging around the puncture wounds.
This procedure becomes less indicative of predation as
the age of the carcass increases or if the remains are scanty or scattered.
Coyotes, foxes, mountain lions, and bobcats usually
feed on a carcass at the flanks or behind the ribs and first consume the liver,
heart, lungs, and other viscera. Mountain lions often cover a carcass with
debris after feeding on it. Bears generally prefer meat to viscera and often
eat first the udder from lactating ewes. Eagles skin out carcasses on larger
animals and leave much of the skeleton intact. With smaller animals such as
lambs, eagles may bite off and swallow the ribs. Feathers and “whitewash”
(droppings) are usually present where an eagle has fed.
Coyotes may kill more than one animal in a single
episode, but often will only feed on one of the animals. Coyotes typically
attack sheep at the throat, but young or inexperienced coyotes may attack any
part of the body. Coyotes usually kill calves by eating into the anus or
abdominal area.
Dogs generally do not kill sheep or calves for food
and are relatively indiscriminate in how and where they attack. Sometimes,
however, it is difficult to differentiate between dog and coyote kills without
also looking at other sign, such as size of tracks (Fig. 2) and spacing and
size of canine tooth punctures. Coyote tracks tend to be more oval-shaped and
compact than those of common dogs. Nail marks are less prominent and the tracks
tend to follow a straight line more closely than those of dogs. The average
coyote’s stride at a trot is 16 to 18 inches (41 to 46 cm), which is typically
longer than that of a dog of similar size and weight. Generally, dogs attack
and rip the flanks, hind quarters, and head, and may chew ears. The sheep are
sometimes still alive but may be severely wounded.
Accurately determining whether or not predation
occurred and, if so, by what species, requires a considerable amount of
knowledge and experience. Evidence must be gathered, pieced together, and then
evaluated in light of the predators that are in the area, the time of day, the
season of the year, and numerous other factors. Sometimes even experts are
unable to confirm the cause of death, and it may be necessary to rely on
circumstantial information.
Legal
Status. The status
of coyotes varies depending on state and local laws. In some states, including
most western states, coyotes are classified as predators and can be taken
throughout the year whether or not they are causing damage to livestock. In
other states, coyotes may be taken only during specific seasons and often only
by specific methods, such as trapping. Night shooting with a spotlight is
usually illegal. Some state laws allow only state or federal agents to use
certain methods (such as snares) to take coyotes. Some states have a provision
for allowing the taking of protected coyotes (usually by special permit) when
it has been documented that they are preying on livestock. In some instances
producers can apply control methods, and in others, control must be managed by
a federal or state agent.
Federal statutes that pertain to wildlife damage
control include the Federal Insecticide, Fungicide, and Rodenticide Act
(FIFRA), which deals with using toxicants, and the Airborne Hunting Act, which
regulates aerial hunting.
Laws regulating coyote control are not necessarily
uniform among states or even among counties within a state, and they may change
frequently. A 1989 Supreme Court action established that it was not legal to
circumvent the laws relative to killing predators, even to protect personal
property (livestock) from predation.
Damage Prevention and Control Methods
Success usually involves an integrated
approach, combining good husbandry practices with effective control methods for
short periods of time. Regardless of the means used to stop damage, the focus
should be on damage prevention and control rather than elimination of coyotes.
It is important to try to prevent coyotes from killing calves or sheep for the
first time. Once a coyote has killed livestock, it will probably continue to do
so if given the opportunity. Equally important is taking action as quickly as
possible to stop coyotes from killing after they start.
Exclusion. Most coyotes
readily cross over, under, or through conventional livestock fences. They are
very intelligent and total exclusion of all coyotes by fencing is highly
unlikely since some eventually learn to either dig deeper or climb higher to
defeat a fence. Good fences, however, can be important in reducing predation
Net-Wire
Fencing. Net fences in good repair will deter many coyotes
from entering a pasture or any other are. Horizontal spacing of the mesh should
be less than 6 inches and vertical spacing less than 4 inches. Digging under a
fence can be discouraged by placing a barbed wire at ground level or using a
buried wire apron. The fence should be about 5 1/2 feet (1.6 m) high to
discourage coyotes from jumping over it. Climbing can usually be prevented by
adding a charged wire at the top of the fence or installing a wire overhang.
Electric
Fencing. Electric fencing, used for years to manage livestock,
has recently been revolutionized by the introduction of new energizers and new
fence designs from Australia and New Zealand. The chargers, now also
manufactured in the United States, have high output with low impedance, are
resistant to grounding, present a minimal fire hazard, and are generally safe
for livestock and humans. The fences are usually constructed of smooth,
high-tensile wire stretched to a tension of 200 to 300 pounds. The original
design of electric fences for controlling predation consisted of multiple,
alternately charged and grounded wires, with a charged trip wire installed just
above ground level about 8 inches outside the main fence to discourage digging.
Many recent designs have every wire charged.
Figure
. Fence extensions are required to keep coyotes from jumping over
a 5-foot fence. Angle the top of a woven-wire fence out about 15 inches and
completely around the fence. An effective fence extends below the surface, or
has a wire apron in front of it to prevent digging
Figure. A six-wire electric fence
can keep coyotes out of an enclosed area.
Two
electrified wires, 8 and 15 inches above ground and offset from an existing
wood fence by 12 inches will prevent coyotes from accessing the fence. A single
strand may be sufficient, but two electrified wires will provide added
insurance.
Coyotes and other predators occasionally become
“trapped” inside electric fences. These animals receive a shock as they enter
the pasture and subsequently avoid approaching the fence to escape. In some
instances the captured predator may be easy to spot and remove from the
pasture, but in others, particularly in large pastures with rough terrain, the
animal may be difficult to remove.
The cost to completely replace old fences with new
ones, whether conventional or electric, can be substantial. In instances where
existing fencing is in reasonably good condition, the addition of one to
several charged wires can significantly enhance the predator-deterring ability
of the fence and its effectiveness for controlling livestock. If coyotes are climbing or jumping a fence,
charged wires can be added to the top and at various intervals. These wires
should be offset outside the fence. Fencing companies offer offset brackets to
make installation relatively simple. The number of additional wires depends on
the design of the original fence and the predicted habits of the predators.
Portable
Electric Fencing. The advent of safe, high-energy chargers has led to
the development of a variety of portable electric fences. Most are constructed
with thin strands of wire running through polyethylene twine or ribbon,
commonly called polywire or polytape. The polywire is available in single and
multiple wire rolls or as mesh fencing of various heights. It can be quickly
and easily installed to serve as a temporary corral or to partition off
pastures for controlled grazing.
Fencing is most likely to be cost-effective where the
potential for predation is high, where there is potential for a high stocking
rate, or where electric modification of existing fences can be used.
Fencing can be effective when incorporated with other
means of control. For example, combined use of guarding dogs and fencing has
achieved a greater degree of success than either method used alone. An electric
fence may help keep a guarding dog in and coyotes out of a pasture. If an
occasional coyote does pass through a fence, the guarding dog can keep it away
from the livestock and alert the producer by barking.
Cultural Methods and Habitat Modification.
Flock
or Herd Health. Healthy sheep flocks and cow/calf herds have higher
reproductive rates and lower overall death losses. Coyotes often prey on
smaller lambs. Poor nutrition means weaker or smaller young, with a resultant
increased potential for predation. Ewes or cows in good condition through
proper nutrition will raise stronger young that may be less vulnerable to
coyote predation.
Altering
Season of Lambing or Calving. The highest
predation losses of sheep and calves typically occur from late spring through
September. This correlates to the mating habits of coyotes, namely coyotes are
most actively seeking food sources for their pups. If possible lambing or
calving program can be seasonally changed to not correlate with the same
activity of the coyotes. Some livestock producers have not only been able to
diversify their marketing program, but have also avoided having a large number
of young animals on hand during periods when coyote predation losses are
typically highest.
Producers who use lambing sheds or pens for raising
sheep and small pastures or paddocks for raising cattle have lower predation
losses than those who lamb or calve in large pastures or on open range. The
more human presence around sheep, the lower the predation losses. Confining
sheep entirely to buildings virtually eliminates predation losses.
Protective
Enclosures, Especially at Night. As
previously discussed coyotes are primarily night predators, It follow that one
of the most effective means of preventing predation is confining sheep and
other small animal in coyote proof sheltered location. Lighted condition adds to the safety of these
structures. Coyotes tend seek prey on foggy or rainy days than on sunny days.
Keeping the sheep penned on foggy or rainy days may be helpful.
Removal
Dead Animals. Coyotes are basically scavengers and given a
choice will feed more readily on an already dead animal than preying on a
living animal. However, carrion tends to
attracts coyotes to a given area thus increasing the chance of predation. Some growers feel that if an abundant amount
of carrion is always present this will reduce predation. Of course the problem arises if carrion
becomes less available resulting in the already present coyotes turning to
predation. A study in Canada showed that the removal of
livestock carcasses significantly reduced overwinter coyote populations and
shifted coyote distributions out of livestock areas.
Habitat Modification. As a rule,
the more open the area where livestock are kept, the less likely that coyote
losses will occur. Often junk piles are located near farmsteads. These serve as
good habitat for rabbits and other prey and may bring coyotes into close
proximity with livestock, increasing the likelihood for opportunistic coyotes
to prey on available livestock. Removing junk piles may be a good management
practice. In addition certain crops are more attractive to rabbits, ground
squirrels and other small rodents (the chief prey of coyotes). When possible removing any situation that
increases the chance of a buildup of these rodents may reduce the presence of
coyotes with subsequent predation on farm animals.
Frightening Devices and Repellents. There are several devices that are available
for attempting to coyotes from a given location. Generally these can be effective provided a
few criteria are met. Coyotes once
establish in a given area are much less likely to be “scared’ from that area
than those that are new to the same area.
Coyotes eventually acclimate (get used to) to such devices over
time. As a consequence if a device is
used continuously in the same area and/or location in that area over a long period
of time it will eventually lose it effectiveness. Sporadically (at different
intervals) using a variety of these devices in an area is far more effective
than using one continuously. Many
frightening devices have been ridiculed in one way or another; nevertheless,
all of the devices discussed below have met with varying degrees of success.
Vehicles. Parking
cars or pickups in the area where losses are occurring often reduces predation
temporarily. Effectiveness can be improved or extended by frequently moving the
vehicle to a new location. Some producers place a replica of a person in the
vehicle when losses are occurring in the daylight. If predators continue to
kill with vehicles in place, the vehicle serves as a comfortable blind in which
to wait and shoot offending predators.
Propane Exploders. Propane
exploders or propane canons produce loud explosions with ignition of propane
gas. Generally speaking the time between
explosions can vary from about 1 minute to 15 minutes. As with most frightening
devices their effectiveness as a coyote deterrent is usually only
temporary. Also their effectiveness can
be significantly increased by relocating the devices to different locations and
by varying the intervals between explosions.
Ideally, the device should be turned on just before dark and off at
daybreak, unless coyotes are killing livestock during daylight hours. Newer
models are now suited with motion sensors which should increase the sensitivity
and effectiveness of these devices. Most experts feel that exploders are best
used as a temporary solution to coyote depredation. As with most frightening devices a great deal
of the success of these devices is dependent on the individuals using them.
A Propane Canon.
Electronic Guard. Developed by the Animal and
Plant Health Inspection Services' (APHIS) Wildlife Services (WS) program, the
Electronic Guard Frightening Device
combines two scare tactics, sound and light. Although it was
created by WS' National Wildlife Research Center (NWRC) to protect sheep from
coyote predation, the Electronic Guard can be used to protect other livestock
and commodities from wildlife damage.
Figure.
Electronic Guard Frightening Device.
A light-sensing device activates the Electronic Guard
at nightfall and turns it off after daybreak, thus operating the machine when
predation is most likely to occur. A timer regulates a siren and a strobe
light--sometimes just flashing the light, sometimes just sounding the siren,
and sometimes doing both at once. This random arrangement helps keep
potential predators at bay. NWRC's tests have shown that using the Electronic
Guard can temporarily reduce predation an average of 80 percent in range and
pasture situations and 60 percent in mountain grazing areas.
For centuries, livestock producers have used
frightening devices to ward off potential predators. Most predators are
initially fearful of unexpected disturbances and keep their distance.
Over the years, the devices have changed from simple scarecrows and bells or
other noisemakers to more modern devices like the Electronic Guard.
The Electronic Guard should be used only when
necessary because most predators eventually learn to ignore the periodic
light-and-sound show. This device is not a cure-all for predation
problems but is one tool in a comprehensive approach to controlling predator
damage. It may help producers complete the lambing season with minimal
loss by stopping predation until sheep can be moved or until other control
methods can be used.
A survey of users of the Electronic Guard by WS found
the device to be successful in keeping black bears out of vineyards and
white-tailed deer out of gardens and cornfields. Customers also report
that they use the Electronic Guard to prevent damage to haystacks and orchards
by elk and deer, discourage beavers from building dams, and frighten birds away
from commercial fish farms.
The number of Electronic Guards needed to protect
sheep will depend on the size of the pasture, the vegetation in or around it,
and the terrain. In general, at least two units should be used in small,
fenced pastures (20-30 acres) or in level pastures with short grass.
Three or four units should be used in large, fenced pastures (31-100 acres),
hilly or wooded pastures, or those with tall grass. In open-range
conditions, the number of Electronic Guards depends on the number of sheep and
the size of the bedground. NWRC testing shows that at least 4 guards
should be used with a band of 1,000 ewes and their lambs.
Guard Dogs. A good
guard dog can protect sheep and goats from coyote damage. Larger breeds, such
as Great Pyrenees, Komondor, Anatolian shepherds and Akbash, often work well to
intimidate the much smaller coyote.
Guard dogs should be acquired as puppies and
habituated to the flock or herd at an early age. Human contact must be kept to
a minimum. If the guard dog is treated as a pet, it will not properly bond with
livestock and its effectiveness will be lost. On the other hand, the guard dog
needs to be tame enough that the owner can approach it for vaccinations,
worming and other care.
Dogs have individual personalities: One dog may
bond with the sheep or goats while another dog may not work as well. A good
guard dog remains with the livestock at all times and confronts coyotes and
other dogs that approach.
Guard dogs require a lot of initial training and
must be provided with shelter and food in the field. They may be excellent
guard animals for a while and become less effective later. Occasionally guard
dogs have been responsible for killing sheep.
Donkeys. Donkies are rapidly gaining popularity in the
United States as guard of sheep and goat flocks against predators. Reportedly in Texas, over 2,400 of the 11,000
sheep and goat producers had used donkeys as guardians.
A single donkey, usually a jennet, sometimes a gelding
(jacks rarely work because they can be too aggressive with lambs) is introduced
to the herd and undergoes a bonding stage. After it has bonded with the sheep,
it will protect them against canine predators (fox, coyote, dogs) as it would
one of its own. This is extremely beneficial in areas where the sheep have many
acres to graze. Donkeys are generally docile to people, but they seem to have
an inherent dislike of dogs and other canids, including coyotes and foxes. In addition the advantage of the donkey over
the guard dog is that they can eat the same food as the sheep so they don't
have to be fed separately. The donkey will also sleep with the sheep at night.
Given a strange sound it will voice a warning to the flock which alerts them to
danger. Then the donkey will chase and often trample the predator. Other
responses can include braying, bared teeth, a running attack, kicking, and
biting. Miniature donkeys are not usually large enough to handle the coyotes,
and mammoth donkeys are usually too slow.
Reported success of donkeys in reducing predation is
highly variable. Improper husbandry or rearing practices and unrealistic
expectations probably account for many failures. Donkeys are significantly
cheaper to obtain and care for than guarding dogs, and they are probably less
prone to accidental death and premature mortality than dogs.
Llamas. Like donkeys, llamas have an inherent dislike of
canids, and a growing number of livestock producers are successfully using
llamas to protect their sheep. A recent study of 145 ranches where guard llamas
were used to protect sheep revealed that average losses of sheep to predators
decreased from 26 to 8 per year after llamas were employed. Eighty percent of
the ranchers surveyed were “very satisfied” or “satisfied” with their llamas.
Llamas reportedly bond with sheep within hours and offer advantages over
guarding dogs similar to those described for donkeys.
Toxicants . Pesticides
have historically been an important component in an integrated approach to
controlling coyote damage, but their use is extremely restricted today by
federal and state laws. All pesticides used in the United States must be
registered with the EPA under the provisions of FIFRA and must be used in
accordance with label directions. Increasingly restrictive regulations
implemented by EPA under the authority of FIFRA, the National Environmental
Policy Act (NEPA), presidential order, and the Endangered Species Act have
resulted in the near elimination of toxicants legally available for predator
damage control.
The only toxicants currently registered for mammalian
predator damage control are sodium cyanide, used in the M-44 ejector device,
and Compound 1080 (sodium monofluoroacetate), for use in the livestock
protection collar. These toxicants are Restricted Use Pesticides and may be
used only by certified pesticide applicators. Information on registration
status and availability of these products in individual states may be obtained
from the respective state’s department of agriculture.
1080
Livestock Protection Collar. The livestock
protection collar (LP collar or toxic collar) is a relatively new tool used to
selectively kill coyotes that attack sheep or goats. Collars are placed on
sheep or goats that are pastured where coyotes are likely to attack. Each
collar contains a small quantity (300 mg) of Compound 1080 solution. The
collars do not attract coyotes, but because of their design and position on the
throat, most attacking coyotes will puncture the collar and ingest a lethal
amount of the toxicant. Unlike sodium cyanide, 1080 is slow-acting, and a
coyote ingesting the toxicant will not exhibit symptoms or die for several
hours. As a result, sheep or goats that are attacked are usually killed. The
collar is registered only for use against coyotes and may be placed only on
sheep or goats.
The LP collar must be used in conjunction with
specific sheep and goat husbandry practices to be most effective. Coyote
attacks must be directed or targeted at collared livestock. This may be
accomplished by temporarily placing a “target” flock of perhaps 20 to 50
collared lambs or kids and their uncollared mothers in a pasture where coyote
predation is likely to occur, while removing other sheep or goats from that
vicinity. In situations where LP collars have been used and found ineffective,
the common cause of failure has been poor or ineffective targeting. It is
difficult to ensure effective targeting if depredations are occurring
infrequently. In most instances, only a high and regular frequency of
depredations will justify spending the time, effort, and money necessary to
become trained and certified, purchase collars, and use them properly.
The outstanding advantage in using the LP collar is
its selectivity in eliminating individual coyotes that are responsible for
killing livestock. The collar may also be useful in removing depredating
coyotes that have eluded other means of control. Disadvantages include the cost
of collars (approximately $20 each) and livestock that must be sacrificed, more
intensive management practices, and the costs and inconvenience of complying
with use restrictions, including requirements for training, certification, and
record keeping. One use restriction limits the collars to use in fenced
pastures only. They cannot be used to protect sheep on open range. Also, collars
are not widely available, because they are registered for use in only a few
states.
Fumigants . Carbon
monoxide is an effective burrow fumigant recently re-registered by the EPA. Gas
cartridges, which contain 65% sodium nitrate and 35% charcoal, produce carbon
monoxide, carbon dioxide, and other noxious gases when ignited. They were
registered by the EPA in 1981 for control of coyotes in dens only. This is the
only fumigant currently registered for this purpose.
Trapping.
Trapping although effective can be quite complicated and typically
require a very experienced individual.
For those interested in the details of trapping please refer to The Internet
Center for Wildlife Damage Management.
Shooting. Shooting coyotes is legal in many
situations, and is considered effective in removing a predator. Of course
safety is of first concern with shooting and its use may be limited by a few
considerations, namely shooting is prohibited in many cities and if allowed may
not be safe due to close neighbors.
Again there are many aspects of shooting but most are beyond the scope
of this document.
Conservation.
Coyotes have long been one of the most controversial of all
non-game animals. Agricultural interests have urged its control by whatever
means necessary so that actual and potential livestock losses may be
eliminated. Since 1891, when the first programs aimed at control were begun in
California, nearly 500,000 coyotes have been reported destroyed at a cost of an
estimated $30 million of the taxpayers' money.
Environmentalists firmly believe that the coyotes are necessary to preserve the
balance of nature. Some sportsmen feel the coyote is responsible for the
declines in game species. Biologists agree that individual animals preying on
livestock and poultry should be destroyed but that the species as a whole is
not necessarily harmful, because much of its diet is made up of destructive
rodents. Biologists also agree that coyote populations have no lasting effects
on other wildlife populations. So the controversy rages on.
Coyotes have recently been classified as non-game animals in California and may
be taken throughout the year under the authority of a hunting license.
Meanwhile, despite the constant hunting and intensive efforts to reduce the
coyote population, on a quiet night the song of the "Little Wolf" may
still be heard throughout the Desert Southwest.
Deer
The white-tailed
deer (Odocoileus
virginianus), also known as the Virginia deer, or simply as the whitetail, is a medium-sized deer native to the United States (all
but five of the states),Canada, Mexico, Central America, and in South America as far
south as Peru. It has
also been introduced to New Zealand and
some countries in Europe, such as Finland and the Czech Republic.
The species is most common east of the Rocky Mountains, and is
absent from much of the western United States, including Nevada, Utah, California, Hawaii, and Alaska (though its close relatives, the mule deer and black-tailed deer Odocoileus
hemionus, can be found there). It does, however, survive in aspen parklands and
deciduous river bottomlands within the central and northern Great Plains, and in
mixed deciduous riparian corridors,
river valley bottomlands, and lower foothills of the northern Rocky Mountain regions
from Wyoming to
southeastern British Columbia. The
conversion of land adjacent to the northern Rockies into agriculture use and
partial clear-cutting of coniferous trees (resulting
in widespread deciduous vegetation) has been favorable to the white-tailed deer
and has pushed its distribution to as far north as Prince George, British Columbia. Populations of deer around the Great Lakes have
also expanded their range northwards, due to conversion of land to agricultural
uses favoring more deciduous vegetation, and local caribou and moose populations. The western most population of the
species, known as the Columbian white-tailed deer, once was widespread in the mixed
forests along the Willamette and Cowlitz River valleys
of western Oregon and
southwestern Washington, but today its numbers have been considerably
reduced, and it is classified as near-threatened. The white-tailed deer is
well-suited for its environment. Fossil records indicate that its basic structure
has not changed in four million years.
Male
and Female White Tailed Deer. Left Image USDA. Right Image Courtesy of Gordon
Robertson
The deer's coat is a reddish-brown in the
spring and summer and turns to a grey-brown throughout the fall and winter. The
deer can be recognized by the characteristic white underside to its tail, which
it shows as a signal of alarm by raising the tail during escape.
The North American male
deer usually weighs from 130 to 300 pounds but, in rare cases, bucks in excess
of 375 pounds have been recorded while the female usually weighs from 90 to 200
pounds. Length ranges from 62 to 87 inches, including the tail, and the
shoulder height is 32 to 40 inches. White-tailed
deer from the tropics tend to be much smaller than temperate populations,
averaging 77–110 pounds.
Males re-grow their
antlers every year. About 1 in 10,000 females also have antlers, although this
is usually associated with hermaphrodites. Bucks
without branching antlers are often termed "spiked bucks". The spikes
can be quite long or very short. Research in Texas has shown that the length
and branching of antlers is genetic and can be influenced by diet. Healthy deer
in some areas that are well fed can have eight point branching antlers as
yearlings (one and a half years old). The
number of points, the length or thickness of the antlers are a general
indication of age but cannot be relied upon for positive aging. A better
indication of age is the length of the snout and the color of the coat, with
older deer tending to have longer snouts and grayer coats. Many say that deer
that have spiked antlers should be culled from the population as they are not
as large or as hardy as bucks with branching antlers, and never will be, but
this is only true in areas where the deer's complete nutritional needs are met,
which is only a small percentage of their range.[9] Spike deer are different from "button bucks" or
"nubbin' bucks", that are male fawns and are generally about six to
nine months of age during their first winter. They have skin covered knobs on
their heads. They can have bony protrusions up to a half inch in length, but
that is very rare, and they are not the same as spikes.
Antlers begin to grow in
late spring, covered with a highly vascular tissue known as velvet. Bucks
either have a typical or non-typical antler arrangement. Typical antlers are
symmetrical and the points grow straight up off the main beam. Non-typical
antlers are asymmetrical and the points may project at any angle from the main
beam. These descriptions are not the only limitations for typical and a typical
antler arrangement. The Boone
and Crockett or Pope & Young
scoring systems also define relative degrees of typical and atypical procedures
to measure what proportion of the antlers are asymmetrical. Therefore, bucks
with only slight asymmetry will often be scored as "typical". A
buck's inside spread can be anywhere from 3–25 inches. Bucks shed their
antlers when all females have been bred, from late December to February.
Although most often
thought of as forest animals depending on relatively small openings and edges,
white-tailed deer can equally adapt themselves to life in more open prairie,
savanna woodlands, and sage communities as in the Southwestern United States,
northern Mexico, These savanna-adapted deer have relatively large antlers in
proportion to their body size and large tails. Also, there is a noticeable
difference in size between male and female deer of the savannas. In western
regions of the United States and Canada, the white-tailed deer range overlaps
with those of the black-tailed deer and mule deer.
Whitetail deer eat large
varieties of food, commonly eating legumes and foraging on other plants, including shoots, leaves, cactus, and grasses. They also eat acorns, fruit, and corn. Their special
stomach allows them to eat some things that humans cannot, such as mushrooms that are poisonous to humans and Red Sumac. Their diet varies in the seasons according to availability
of food sources. They will also eat hay and other food that they can find in a
farm yard. Whitetail deer have been known to opportunistically feed on nestling
songbirds, and well as field mice, and birds trapped in Mist nets.[13]
There are several
natural predators of white-tailed deer. Gray wolves, cougars, American
alligators and (in the tropics) jaguars are the more effective natural predators of adult deer. Bobcats, lynxes, bears and packs of coyotes usually will prey on deer fawns. Bears may sometimes attack
adult deer while lynxes, coyotes and bobcats are most likely to take adult deer
when the ungulates are weakened by winter weather. The general extirpation of natural
deer predators over the East Coast (only the coyote is now widespread) is
believed to be a factor in the overpopulation issues with this species. Many
scavengers rely on deer as carrion, including New World vultures, hawks, eagles, foxes and corvids (the latter three may also rarely prey on deer fawns).
Females enter estrus, colloquially called the rut, in the fall, normally in late October or early November,
triggered mainly by declining photoperiod. Sexual maturation of females depends on population
density. Females can mature in
their first year, although this is unusual and would occur only at very low
population levels. Most females mature at 1–2 years of age. Most are not able
to reproduce until six months after they mature.
Males compete for the
opportunity of breeding females. Sparring among males determines a dominance
hierarchy. Bucks will attempt to
copulate with as many females as possible, losing physical condition since they
rarely eat or rest during the rut. The general geographical trend is for the
rut to be shorter in duration at increased latitude. There are many factors as
to how intense the "rutting season" will be. Air temperature is one
major factor of this intensity. Any time the temperature rises above 40 degrees
Fahrenheit, the males will do much less traveling looking for females, or they
will be subject to overheating or dehydrating. Another factor for the strength
in rutting activity is competition. If there are numerous males in a particular
area, then they will compete more for the females. If there are fewer males or
more females, then the selection process will not need to be as competitive.
Females give birth to
1–3 spotted young, known as fawns, in mid to late spring, generally in May or
June. Fawns lose their spots during the first summer and will weigh from 44 to
77 pounds by the first winter. Male fawns tend to be slightly larger and
heavier than females.
White-tailed deer
communicate in many different ways using sounds, scent, body language, and
marking. All white-tailed deer are capable of producing audible noises, unique
to each animal. Fawns release a high-pitched squeal, known as a bleat, to call
out to their mothers. Does also bleat. Grunting produces a low, guttural sound
that will attract the attention of any other deer in the area. Both does and
bucks snort, a sound that often signals danger. As well as snorting, bucks also
grunt at a pitch that gets lower with maturity. Bucks are unique in their
grunt-snort-wheeze pattern that often shows aggression and hostility. Another
way white-tailed deer communicate is with their white tail. When a white-tail
deer is spooked it will raise its tail to warn the other deer in the area that
can see them.
Though human encounters
are rare there is only an average of four cases of human casualties each year
in the highly populated areas such as Minnesota, North and South Dakota, and
Wisconsin. Usually, white-tailed deer will not approach a human unless it
smells a bucks urine on the person.
White-tailed deer
possess many glands that allow them to produce scents, some of which are so
potent they can be detected by the human nose. Four major glands are the
pre-orbital, forehead, tarsal, and metatarsal glands. It was originally thought
that secretions from the pre-orbital glands (in front of the eye) were rubbed
on tree branches; recent research suggests this is not so. It has been found
that scent from the forehead glands (found on the head, between the antlers and
eyes) is used to deposit scent on branches that overhang "scrapes"
(areas scraped by the deer's front hooves prior to rub-urination). The tarsal
glands are found on the upper inside of the hock (middle joint) on each hind
leg. Scent is deposited from these glands when deer walk through and rub
against vegetation. These scrapes are used by bucks as a sort of
"sign-post" by which bucks know which other bucks are in the area,
and to let does know that a buck is regularly passing through the area—for breeding
purposes. The scent from the metatarsal glands, found on the outside of each
hind leg, between the ankle and hooves, may be used as an alarm scent.
Throughout the year deer
will rub-urinate, a process during which a deer squats while urinating so that
urine will run down the insides of the deer's legs, over the tarsal glands, and
onto the hair covering these glands. Bucks rub-urinate more frequently during
the breeding season. Secretions from the tarsal gland mix with the urine and
bacteria to produce a strong smelling odor. During the breeding season does
release hormones and pheromones attract bucks for mating. Bucks also rub trees
and shrubs with their antlers and head during the breeding season, possibly
transferring scent from the forehead glands to the tree, leaving a scent other
deer can detect.
Sign-post marking
(scrapes and rubs) are a very obvious way that white-tailed deer communicate.
Although bucks do most of the marking, does visit these locations often. To
make a rub, a buck will use its antlers to strip the bark off of small diameter
trees, helping to mark his territory and polish his antlers. To mark areas they
regularly pass through bucks will make scrapes. Often occurring in patterns
known as scrape lines, scrapes are areas where a buck has used its front hooves
to expose bare earth. They often rub-urinate into these scrapes, which are
often found under twigs that have been marked with scent from the forehead
glands.
A century ago,
commercial exploitation, unregulated hunting and poor land-use practices, including deforestation
severely depressed deer populations in much of their range. For example, by
about 1930, the U.S. population was thought to number about 300,000. After an
outcry by hunters and other conservation
ecologists, commercial
exploitation of deer became illegal and conservation programs along with
regulated hunting were introduced. Recent estimates put the deer population in
the United States at around 30 million. Conservation practices have proved so
successful that, in parts of their range, the white-tailed deer populations
currently far exceed their carrying capacity and the animal may be considered a
nuisance. Motor vehicle collisions with deer are a serious problem in many parts of the
animal's range, especially at night and during rutting season, causing injuries
and fatalities among both deer and humans. Vehicular damage can be substantial in some cases. At high
population densities, farmers can suffer economic damage by deer depredation of
cash crops, especially in corn and orchards. Deer can prevent successful reforestation following
logging, and have impacts on native plants and animals in parks and natural
areas. Deer also cause substantial damage to landscape plants in suburban areas,
leading to limited hunting or trapping to relocate or sterilize them.
Deer Damage. Usually, deer damage plants by browsing on new vegetation
during the growing season. However, when food is scarce, deer will eat just
about anything to survive. One of the reasons that deer are becoming more of a
problem in many parts of the United States is that their numbers are
increasing. An Associated Press article on October 15, 2000 stated:
The national deer population, now estimated at
25 million to 30 million, has been growing for decades. Not only have deer
adapted to encroaching suburbia, but they have benefited from a series of mild
winters, an increase in newly developed areas being declared off limits for
hunters and a decline in hunting in some parts of the country . . . Some
forecasters believe there could be a point when the deer population will become
so large it just can't sustain itself. But no one knows when. "We're not
certain when it will max out," Curtis [wildlife biologist Paul Curtis of
Cornell University] said. "Deer populations are already at densities a
biologist wouldn't have dreamed of 10 years ago."
The cost of damage by deer will vary greatly,
according to the crops and plants being grown in relation to the number of deer
browsing. In the article "Oh, Deer" in the June-July 2002 Farmer's
Digest, Jim Armstrong, associate professor and wildlife specialist with Auburn
University, explained that it is not uncommon for some growers in the Southeast
to have $20,000 to $30,000 in crop damage (peanuts and cotton) during a crop
year. He says:
It's a widespread problem in agriculture. The
problem is that it tends to be very site-specific. Depending on the habitat
around the field, one person can have no damage and the next can have a lot of
problems. Deer prefer a fragmented habitat that consists of both woodland for
cover and open cropland. Farmers may notice more feeding near the edges of the
fields near woods, where the deer can feed without straying too far from cover.
(Mullen, 2002)
The USDA estimates that total deer damage from
auto collisions and crop and timber losses reaches at least $1 billion a year
Control. Because deer are protected by game regulations in all
states, as well as all Canadian provinces, I strongly suggest you contact the
specific wildlife, natural resource, or conservation agency that enforces your
state's wildlife regulations before implementing any deer control practice.
Some state agencies have specific programs for technical assistance or to
compensate for deer damage. Other states, or even local municipalities, may
have laws restricting some options for deer management. Producers need to keep
current with their state laws and regulations, because they can change from
year to year.
The Wildlife Services (WS), an arm of the Animal
and Plant Health Inspection Service (APHIS) charged with helping to prevent or
reduce wildlife damage, provides technical assistance or direct control. For
more information about assistance, contact any state APHIS office. The address
and phone number of each state's Wildlife Services State Director and the state's
Wildlife Services activity report is available by calling the national Wildlife Services
Operational Support staff at (301) 734-7921.
There are five general methods for preventing or
controlling deer damage to crops. These include exclusion, cultural methods,
scare devices, repellents, and culling or harvest.
Exclusion. Several methods of exclusion are available. They
can involve permanent or temporary fences, a wireless deer fence, or other
methods of keeping deer from getting to the plants to browse.
Fencing. The most effective method for exclusion is a well-designed
fence, and there are several designs available to meet specific needs.
Temporary electrified fences are simple, inexpensive, and useful in protecting
garden and field crops during snow-free periods. "Baiting" the fence
with peanut butter, apples, etc. may enhance the effectiveness of electrified
fences. Deer are attracted to these fences by their appearance or smell and are
lured into contacting the fence with their noses. This causes an effective
shock that trains deer (sometimes) to avoid the fenced area. Permanent,
high-tensile, electric fences provide year-round protection from deer and are
best suited to high-value specialty or orchard crops.
Permanent woven-wire
fences provide the ultimate deer barrier. They require little maintenance but
are very expensive to build. In fact, the cost of constructing effective fences
often limits their use to areas of intensive agriculture, such as orchards or
private gardens.
The Cornell publication Managing White-Tailed Deer in
Suburban Environments: A Technical Guide states: For a given deer density, the potential for damage will
often be greater on large plantings than smaller ones. Consequently, large
areas often require more substantial fencing designs to achieve a level of
protection similar to small areas. Based on reports and research experiences in
New York, vertical electric fence designs seldom provide reliable protection
for plantings larger than five acres under intense deer foraging pressure.
Slant-wire, electric-fencing systems can protect plantings approximately 50
acres in size. Blocks larger than 50 acres usually require eight-foot-high,
woven-wire fencing to reliably prevent deer from entering the area if feeding
pressure is high.
The same publication
suggests that fencing systems such as the baited electric wire, fences with
three-dimensional outriggers, and slanted and vertical fences up to 11-feet
high have kept deer out under some conditions. However, it continues: Often simple designs are effective only under light deer
pressure or for relatively small areas. Often simple designs are effective only under light deer
pressure or for relatively small areas. during the growing season when
alternative foods are available to deer. Low-profile fences, however, are
seldom satisfactory for
protecting commercial orchards or ornamental plantings in winter, especially if
snow restricts deer from using alternative food sources. Landowners must also check
local ordinances and covenants to determine if electric fences can be used, or
if fences of any kind can be constructed on their property.
Cultural
Methods. Deer
damage to landscape plants and flowers usually occurs when the deer's natural
browse is low, generally in the late fall through early spring. By choosing
species that are undesirable to deer, you can reduce the amount of damage to
these plants. Plants with a bitter or spicy taste, milky sap, or thorny, hairy,
or tough leaves and stems are unpalatable to deer. However, the presence of
undesirable plants does not deter deer from feeding on other nearby plants that
they do find palatable. If there is intensive feeding pressure caused by
drought or snow or a high deer density, deer will browse even the most
undesirable plants, and other methods will be necessary to control damage.
Scare Devices. Methods for frightening
or hazing deer may be effective and economical in some situations, especially
at the first sign of a problem. Once deer establish a pattern of movement, it
is difficult to get them to change. Propane cannons or gas exploders set to
detonate at irregular intervals are the most common scare devices, and they are
sometimes available for loan from wildlife refuges or wildlife agencies. Strobe
lights and sirens can also be effective; even fireworks and gunfire can be used
as a temporary method. Playing a radio that goes on and off during the night
will work for a short time, as will attaching a sprinkler system or lights to
motion detectors. The problem with all scare devices is that deer become
accustomed to them within a week or two, even when the devices are moved
occasionally. Varying the scare devices every week may extend the protection for
a longer period. Scare devices are usually a great short-term solution, but
don't depend on them for a whole growing season.
Dogs. Another scare option is the
use of dogs that are kept behind an "invisible" fence by the use of a
radio transmitter, an underground copper wire, and a special dog collar with
receivers. Stationed inside the invisible fence, the dogs chase the deer out of
the dogs' territory. The collar, when activated by the underground wire, first
gives an audible signal, and if the dogs don't stop they receive a mild,
harmless shock. The dogs must be trained to heed the signals. Placing the dogs'
kennel and water in one area and the food in another area may help keep the
dogs moving around their territory.
The Cornell publication Managing White-Tailed Deer in
Suburban Environments: A Technical Guide suggests
that the effective area covered by 2 dogs behind invisible fence is about 60
acres or 500 yards from their kennel during the summer. The area is reduced to
about 10 acres during winter, when snow restricts the movement of the dogs,
though snowfall doesn't affect operation of the electronics.
The same publication
cautions that care and feeding of the dogs can be time-consuming and that a
family pet may not provide adequate protection, because it is not patrolling
all the time. The authors explain: "The breed and disposition of the dog
will influence effectiveness of this technique. Large dogs that aggressively
patrol the area appear to work best. The complete protection of plant materials
should not be expected, as deer react to dogs similar to other scare devices or
repellents
Repellents. Repellents are best
suited for high-value crops in orchards, nurseries, and gardens. High cost,
limitations on use, and variable effectiveness make most repellents impractical
on row crops, pasture, or other large areas. There are two kinds of repellents:
contact and area. Contact repellents are applied directly to the crop plants
and repel by taste. Some of these contact repellents use inedible egg solids to
repel deer, while others are derived from cayenne pepper extract and cannot be
applied to the edible portion of the crop because they will leave a hot taste.
Repellents made from rotten eggs have worked better than several other products
in an Alabama Experiment Station test. Area
repellents are applied near the plants to be protected and repel deer by smell
alone. Some area repellents use ammonium soaps of fatty acids, bone tar oil,
and/or putrefied meat scraps. Bags of human hair and suspended bars of ordinary
hand soap can also be used as area repellents for deer.
The deer's learning
ability causes many repellents to fail over time. A good way to counter such
acclimation is to switch repellents periodically and to alter their positions
near the crop. But as with planting unpalatable ornamentals, remember that hungry deer will ignore both taste and odor
repellent
Culling or Harvest. Culling the animals is another management
option. Some states issue permits to landowners to shoot deer outside the normal
sport hunting season. Only those animals that are damaging crops can be
removed, and such permits are often publicly controversial.
Sport hunting can reduce
deer populations and damage over larger regional areas. To be effective over
the long term, does (female deer) must be removed from the deer population. A
"bucks-only" deer hunt does little to reduce the deer population or
the damage done by overpopulated deer herds. Landowners can reduce the deer
population in their area by soliciting hunters who have "either-sex"
deer permits and who will shoot does. By allowing hunting, landowners can
provide controlled public access to a recreational resource while reducing deer
damage.
Bats.
Big
Eared Bat. Image Courtesy of Bureau Land
Management.
Many people needlessly fear bats.
These actions emphasize the need to educate the public on the reasons for bat
conservation and why it is important to use safe, nondestructive methods to
alleviate conflicts between people and bats. General sources of information on
bats include states’ Cooperative Extension Services, universities, government
environmental conservation and health departments, and Bat Conservation
International. Except where control is necessary, bats should be appreciated
from a distance — and not disturbed. This is especially important since bats
serve a very important function in various ecosystems including control of a
number of insect pest species.
Bats, the only mammals that truly
fly, belong to the order Chiroptera. Their ability to fly, their secretiveness,
and their nocturnal habits have contributed to bat folklore, superstition, and
fear. They are worldwide in distribution and include about 900 species, second
in number only to the rodents among the mammals.
Bats are one of the most numerous and diverse groups
of mammals, existing on every continent except Antarctica. The world’s current
bat fauna represents over 50 million years of adaptation to a variety of
environmental conditions and unique niches. The only true flying mammals, bats
are fascinating for a variety of reasons, including the ways their bodies have
evolved for flight. Millions of years ago, bat forelimbs evolved into wings and
their hips rotated 180 degrees, allowing the animals to hang by their feet.
Bats also developed the ability to echolocate, or use sound to locate objects
and orient themselves in their environment, which helps them navigate through
caves and forests as well as locate prey.
There are over 1,000 species of bats, each playing an
essential role in their environment— including consuming vast quantities of
insects. As an additional perk, bats redistribute nutrients throughout the
forest in their guano. Many bat species also feed on pollen and fruit, serving
as pollinators and seed dispersers. Though abundant in the United States before
1900, 13 percent of bat species are now at risk of extinction due to human
disturbance. Studying and understanding the lifestyle patterns of these animals
is essential to reversing species decline.
Among the 40 species of bats found
north of Mexico, only a few cause problems for humans (note that vampire bats
are not found in the United States and Canada). Bats congregating in groups are
called colonial bats; those that live alone existence are known as solitary
bats.
The colonial species most often
encountered in and around human buildings in the United States are the little
brown bat, the big brown bat, the Mexican free-tailed bat, the pallid bat, the Yuma myotis and the evening bat.
Solitary bats typically roost in tree foliage or under bark, but occasionally
are found associated with buildings, some only as transients during migration
Bats inhabiting buildings produce offensive
odors and distracting noise. Bats can carry rabies. Transmission need not be
from a bite from an infected bat; there is evidence that exposure of abraded
skin to bat urine, or even inhalation of cave air may be infective. At least
eight of the 24 species in California have been found to be sometime infected.
As there are no true bloodsucking bats in the United States, a bite is unlikely
unless one is handling or otherwise disturbing bats. Brown bats are reservoir hosts for encephalitis which may be
transmitted to humans by mosquitoes. Encephalitis can cause death and mental
retardation. Histoplasmosis, a systemic fungus disease of man, may be
contracted by inhalation of dusty bat manure containing air-borne spores of the
fungus.
The California myotis bat and the big brown bat are
found throughout the state except in the high mountain zones. The other 22 bats
found in California occupy various portions of the state, with considerable
overlap of distribution. The hoary bat, the silver-haired bat, and the red bat
migrate to the coast in winter, but other species are permanent residents.
All of these bats are nocturnal, roosting in
crevices, caves, tunnels, free foliage or building during the day. Some species
have a separate night roost to which they retire between feeding flights. Some
species are more particular about the kind of roost they select than others;
many hibernate in caves in winter, and may move from one cave to another
several times. The most stationary species may inhabit the same roost
throughout the year.
Bats vary widely in size - the smallest mammal
in the world is the bumblebee bat of Thailand (smaller than a dime), while some
of the fruit bats (also known as “flying foxes”) of the Asian tropics can have
a wingspan of up to six feet. Their shape also varies between species and
usually corresponds with food type and highly specialized hunting or foraging
habits. For instance, certain insect-eating bats that feed over water have very
different feet, wings and ears than bats that catch insects in mid-air. Contrary
to popular belief, more than 70% of bats eat insects, with much of the
remainder being tropical species that feed on fruit and nectar. A few are
carnivorous, eating small fish, birds and frogs. Only three species of bat are
vampires, totally subsisting on blood, and they are only found in South
America. Sadly, bats all over the world have been targeted by humans based upon
an unfounded fear that they are vampire bats when really they eat insects or
fruit.
As indicated bats are the only truly flying mammal species. This is part of the
reason that they roost upside-down; because they don’t have the strength, like
birds, to launch themselves into flight from standing, they drop from a hanging
position directly into flight. Hanging upside-down also allows them to rest
safely away from predators. Some bats are solitary and travel and roost alone
or in small groups, while others prefer to congregate in large colonies of
millions of bats. They are a commuting, migratory species, meaning they move
from place to place on a nightly basis from a few to hundreds of miles. Like
humans, bats give birth to live, helpless young and breast feed them on milk
for several months, making them, for their size, the slowest reproducing
mammals on earth. They are also quite long-lived for their size—some species
can live into their thirties!
Bats rely on reflection of high-pitched squeaks they
emit to avoid collisions and to determine location of prey. Most bats live
almost totally on insects captured and eaten on the wing, though two Southern
California bats eat nectar, pollen and fruit as well. Bats in other parts of
the world include vampires, small-fish catchers, day flyers, and large fruit
eaters (“flying foxes”) with wingspans over five feet. Vampires and some
mastiff bats can fold their wings and run about on all fours. Bats hang upside
down when resting and many species conserve energy during the day by lowering
body temperature (and hence metabolism) to near that of the surrounding air.
Many bats hibernate in winter by a similar process.
Reproductive information on many bat species is
scanty. Breeding occurs in autumn before hibernation, or at the winter roost,
depending on the species. Mature males are recognizable at this time by the
swelling of the testes in the abdomen. Ovulation occurs after winter dormancy
is over, at which time the stored sperm fertilized the egg. The young (usually
only one or two, though a few species bear up to four) are born two to three
months later, in May to July. Young are born naked and many cling to their
mother for some time after birth; no nest is ever built. The young are able to
fly at three to four weeks though some continue to nurse for several weeks
longer. In many species the adults segregate when the young are born, each male
lives alone through the summer while the females remain together. Most species
of bats are colonial but some are solitary; both conditions may occur in some
species. Bats have few enemies (owls, snakes) and some bats live to 20 years or
more.
Legal Status. Bats are classified as nongame mammals
by California Fish and Game Code. Nongame mammals which are found to be
injuring growing crops or other property may be taken by the owner or tenant of
the premises, except that if leg-hold steel-jawed traps are used they shall not
have saw-toothed or spiked jaws or have a spread of 5 ½ inches or larger
without offset jaws. They may also be taken by officers or employees of the
California Department of Food and Agriculture or by federal or county officers
or employees when acting in their official capacities pursuant to the provision
of the Food and Agricultural Code pertaining to pests.
Little Brown Bat. This bat is pale tan through reddish brown to
dark brown, depending on geographic location. The species is a rich dark brown
in the eastern United States and most of the west coast. Fur is glossy and
sleek.
Little
Brown Bat. Image Courtesy of Pipistrellus_pipistrellus01.jpg
This is one of the most common bats
found in and near buildings, often located near a body of water where they
forage for insect prey. Summer colonies are very gregarious, commonly roosting
in dark, hot attics and associated roof spaces where maternity colonies may
include hundreds to a few thousand individuals. Colonies may also form beneath
shingles and siding, in tree hollows, beneath bridges, and in caves. Litter
size is 1 in the Northeast; twins occasionally occur in some other areas. The
roost is often shared with the big brown bat (E. fuscus) though the latter is less tolerant of high temperatures;
M. keenii may also share the same site. Separate groups of males tend to be
smaller and choose cooler roosts within attics, behind shutters, under tree
bark, in rock crevices, and within caves.
In the winter, little brown bats in
the eastern part of their range abandon buildings to hibernate in caves and
mines. Such hibernacula may be near summer roosts or up to a few hundred miles
(km) away. Little is known of the winter habits of M. lucifugus in the western United States. The life span of little
brown bats has been established to be as great as 31 years. The average life
expectancy, however, is probably limited to only a few years.
Big Brown Bat (Eptesicus
fuscus). Coloration varies from reddish brown,
copper colored, to a dark brown depending on geographic location. This is a
large bat without distinctive markings. This hardy, rather
sedentary species appears to favor buildings for roosting. Summer maternity
colonies may include a dozen or so and up to a few hundred individuals,
roosting behind chimneys, in enclosed eaves, in hollow walls, attics, barns,
and behind shutters and unused sliding doors. They also form colonies in rock
crevices, beneath bridges, in hollow trees, and under loose bark. Litter size
is 2 in the East to the Great Plains; from the Rockies westward 1 young is
born.
The big brown bat is one of the most
widely distributed of bats in the United States and is probably familiar to
more people than any other species. This is partially due to its large,
easy-to-observe size, but also to its ability to overwinter in buildings
(attics, wall spaces, and basements). Its close proximity to humans, coupled
with its tendency to move about when temperature shifts occur, often brings
this bat into human living quarters and basements in summer and winter. Big
browns also hibernate in caves, mines, storm sewers, burial vaults, and other
underground harborage. While this bat will
apparently travel as far as 150 miles (241 km) to hibernacula, the winter
quarters of the bulk of this species are largely unknown.
Mexican Free-Tailed Bat (Tadarida
brasiliensis). This species is dark brown or dark
gray. Fur of some individuals may have been bleached to a pale brown due to
ammonia fumes from urine and decomposing guano. Confusion is not likely to
occur with other species that commonly inhabit human buildings.
Mexican Free-Tailed Bat. Image Courtesy of USGS
This species
forms the largest colonies of
any warm-blooded animal, establishing sizable colonies in buildings,
particularly on the West Coast and in the Gulf states from Texas east. Hundreds
to thousands may be found in buildings or under bridges. It is primarily a cave
bat in Arizona, New Mexico, Oklahoma, and Texas; buildings are used as
temporary roosts during migrations. Litter size is 1.
This bat often share roosts with
other species. In the West, for example, they may be found in buildings with
the pallid bat and big brown bat. Some males are always present in the large
maternity colonies, but they tend to segregate in separate caves.
A few may overwinter in buildings as
far north as South Carolina in the East and Oregon in the West. Most of this
species migrate hundreds of miles to warmer climes (largely to Mexico) for the
winter.
Pallid Bat (Antrozous pallidus). The pallid bat is
two and a half to three inches long and has a one and a half to two and a
quarter inch long tail. It weighs a half to one and one sixteenth ounces. Its
nose is reminiscent to that of a pig. It has wooly fur. Its coloring is paler
then many species of bats. It is pale cream or light brown on the back and very
pale to white on the torso. There are glands on the face of the pallid bat that
emit a skunk-like odor that is probably used as a defense mechanism.
Pallid
Bat. Image Courtesy USGS.
The pallid
bat's range stretches from western North America to Mexico. They are also found
in Cuba. It prefers dry habitats and is present in a wide variety of habitats
from grassland to scrubby desert. It even inhabits Death Valley in California,
a desert of extreme heat
The pallid bat lives in groups. The colony roosts
together during the day in rocky outcrops, trees or attics. They will rally
each other together with piercing directive cries to locate their roost.
Maternity colony size ranges from about 12 to 100 individuals. Roost sites
include buildings, bridges, and rock crevices; less frequently, tree cavities,
caves, and mines. Litter size is most commonly 2. The roost is frequently
shared with T. brasiliensis and E. fuscus in the West. While groups of
males tend to segregate during the nursery period (sometimes in the same
building), other males are found within the maternity colony.
An interesting feature of pallid bats is
that they fly close to the ground, may hover, and take most prey on the ground,
not in flight. Prey includes crickets, grasshoppers, beetles, and scorpions.
They will also forage among tree foliage. Pallid bats are not known to make
long migrations, though little is known of their winter habits.
The breeding season of the pallid bat occurs only
once per year beginning in October and lasting until the end of winter.
Gestation or pregnancy usually lasts fifty three to seventy one days. The
female pallid bat produces a litter of one or two young. Most litters have two
young. Single births occur twenty percent of the time. They learn to fly at
four to five weeks old and are weaned at six to eight weeks old. Both the male
and the female pallid bat are sexually mature in less than a year and able to
breed during their first breeding season. The maximum lifespan for this species
in the wild is nine years. In captivity the maximum lifespan is eleven years.
California Myotis Bat.
This species ranges from Southern Alaska and western Canada south ward through
most of Mexico. It is one of the smallest bats in the United States
occupying a variety of habitats in the Pacific Northwest and southern and
western British Columbia, from the humid coastal forest to semi-desert, and
from sea level to at least 1,800 meters (5,940 feet) elevation. In arid
regions, it usually occurs in the vicinity of water. Individuals emerge shortly
after sunset to for age, which continues at irregular intervals until dawn. Its
flight is slow and erratic and it hunts primarily along margins of tree clumps,
around the edge of the tree canopy, over water, and well above ground in open
country. California bats roost in rock crevices, hollow trees, spaces
under loose bark, and in buildings. The sexes roost separately during summer
when females form small maternity colonies, but occur together from September
to March. California bats hibernate in caves and mines.
General Bat
Biology. The California bat feeds on small flying insects, primarily flies,
moths, and beetles. Its foraging strategy consists of locating and feeding in
concentrations of insects where its slow maneuverable flight allows it to
capture several insects in quick succession over a short distance.
Food Habits. Bats in North America are virtually all insectivorous, feeding on
a variety of flying insects (exceptions among house bats were noted previously. Many of the insects are
harmful to humans. While there must be some limitations based on such factors
as bats’ body size, flight capabilities, and jaw opening, insectivorous bats
apparently consume a wide range of prey. The little brown bat’s diet includes
mayflies, midges, mosquitoes, caddis flies, moths, and beetles. It can consume
insects equal to one-third of its body weight in 1/2 hour of foraging. The big
brown bat may fill its stomach in about 1 hour (roughly 0.1 ounce per hour [2.7
g/hr]) with prey including beetles, moths, flying ants, true bugs, mayflies,
caddis flies, and other insects. The nightly consumption of insects by a colony
of bats can be extremely large.
General Biology, Reproduction, and
Behavior. Most North American bats emit high frequency
sounds (ultrasound) inaudible to humans and similar to sonar, in order to avoid
obstacles, locate and capture insect prey, and to communicate. Bats also emit
audible sounds that may be used for communication between them.
Bats generally mate in the fall and
winter, but the female retains the sperm in the uterus until spring, when
ovulation and fertilization take place. Pregnant females may congregate in
maternity colonies in buildings, behind chimneys, beneath bridges, in tree
hollows, caves, mines, or other dark retreats. No nests are built. Births
typically occur from May through July. Young bats grow rapidly and are able to
fly within 3 weeks. Weaning occurs in July and August, after which the nursery
colonies disperse.
Bats prepare for winter around the
time of the first frost. Some species migrate relatively short distances,
whereas certain populations of the Mexican free-tailed bat may migrate up to
1,000 miles (1,600 km). Bats in the northern United States and Canada may
hibernate from September through May. Hibernation for the same species in the
southern part of their range may be shorter or even sporadic. Some may fly
during warm winter spells (as big brown bats may in the northeastern part of
the United States). Bats often live more than 10 years.
In response to a variety of human
activities, direct and indirect, several bat species in the United States have
declined in number during the past few decades. Chemical pesticides
(particularly the use of persistent and bioaccumulating organic pesticides)
have decreased the insect supply, and contaminated insects ingested by bats
have reduced bat populations. Many bats die when people disturb summer
maternity roosts and winter hibernacula. Vandals and other irresponsible
individuals may deliberately kill bats in caves and other roosts. Even the
activities of speleologists or biologists may unintentionally disturb
hibernating bats, which depletes fat reserves needed for hibernation.
Modification and destruction of
roost sites has also decreased bat numbers. Sealing and flooding of mineshafts
and caves and general quarrying operations may inadvertently ruin bat
harborages. Forestry practices have reduced the number of hollow trees
available. Some of the elimination of natural bat habitat may contribute to
bats roosting in buildings.
Damage and Damage Identification. Bats often fly about swimming pools, from which they drink or
catch insects. White light (with an ultraviolet component), commonly used for
porch lights, building illumination, street and parking-lot lights, may attract
flying insects, which in turn attract bats. Unfortunately, the mere presence of
a bat outdoors is sometimes beyond the tolerance of some uninformed people.
Information is a good remedy for such situations.
Bats commonly enter buildings
through openings associated with the roof edge and valleys, eaves, apex of the
gable, chimney, attic or roof vent, dormers, and siding.
Other openings may be found under loose-fitting
doors, around windows, gaps around various conduits (wiring, plumbing, air
conditioning) that pass through walls, and through utility vents.
Bats are able to squeeze through
narrow slits and cracks. For purposes of bat management, one should pay
attention to any gap of approximately 1/4 x 1 1/2 inches (0.6 x 3.8 cm) or a
hole 5/8 x 7/8 inch (1.6 x 2.2 cm). Such openings must be considered potential
entries for at least the smaller species, such as the little brown bat. The
smaller species require an opening no wider than 3/8 inch (0.95 cm), that is, a
hole the diameter of a US 10-cent coin. Openings of these dimensions are not
uncommon in older wood frame structures where boards have shrunk, warped, or
otherwise become loosened.
The discovery of one or two bats in
a house is a frequent problem. In the Northeast, big brown bats probably
account for most sudden appearances. Common in urban areas, they often enter
homes through open windows or unscreened fireplaces. If unused chimneys are
selected for summer roosts, bats may fall or crawl through the open damper into
the house. Sometimes bats may appear in a room, and then disappear by crawling
under a door to another room, hallway, or closet. They may also disappear
behind curtains, wall hangings, bookcases, under beds, into waste baskets, and
so forth. Locating and removing individual bats from living quarters can be
laborious but is important. If all else fails, wait until dusk when the bat may
appear once again as it attempts to find an exit. Since big brown bats may
hibernate in the cooler recesses of heated buildings, they may suddenly appear
(flying indoors or outdoors) in midwinter during a warm spell or a cold snap as
they move about to adjust to the temperature shift.
Roosting
Sites. Bats use roosting niches that are indoors (human dwellings,
outbuildings, livestock quarters, warehouses), semi-enclosed (loading docks,
entrance foyers), partially sheltered (porches, carports, pavilions, highway
underpasses, bridges), and open structural areas (window shutters, signs). Once
there, active bats in and on buildings can have several economic and aesthetic
effects, often intertwined with public health issues. Unusual roosting areas
include wells, sewers, and graveyard crypts. Before considering control measures, verify that bats are actually
the cause of the problem.
Rub
Marks. Surface
areas on walls, under loose woodwork, between bricks and around other bat
entryways often have a smooth, polished appearance. The stained area is
slightly sticky, may contain a few bat hairs, and is yellow-brown to blackish
brown in color. The smooth gloss of these rub marks is due to oils from fur and
other bodily secretions mixed with dust, deposited there as many animals pass
repeatedly for a long period over the same surface. Openings marked in this way
have been used heavily by bats.
Noise. Disturbing
sounds may be heard from vocalizations and grooming, scratching, crawling, or
climbing in attics, under eaves, behind walls, and between floors. Bats become
particularly noisy on hot days in attics, before leaving the roost at dusk, and
upon returning at dawn. Note that rustling sounds in chimneys may be caused by
birds or raccoons and scratching and thumping sounds in attics and behind walls
may indicate rats, mice, or squirrels.
Guano
and Urine. Fecal pellets indicate the presence of animals and are found on
attic floors, in wall recesses, and outside the house at its base. Fecal
pellets along and inside walls may indicate the presence of mice, rats, or even
roaches. Since most house bats north of Mexico are insectivorous, their
droppings are easily distinguished from those of small rodents. Bat droppings
tend to be segmented, elongated, and friable. When crushed, they become powdery
and reveal shiny bits of undigested insect remains. In contrast, mice and rat
droppings tend to taper, are unsegmented, are harder and more fibrous, and do
not become powdery when crushed (unless extremely aged).
The droppings of some birds and
lizards may occasionally be found along with those of bats. However, bat
droppings never contain the white chalky material characteristic of the feces
of these other animals.
Bat excrement produces an unpleasant
odor as it decomposes in attics, wall spaces, and other voids. The pungent,
musty, acrid odor can often be detected from outside a building containing a
large or long-term colony. Similar odor problems occur when animals die in
inaccessible locations. The odor also attracts arthropods which may later
invade other areas of a building.
Bat guano may provide a growth
medium for microorganisms, some of which are pathogenic (histoplasmosis, for
example) to humans. Guano accumulations may fill spaces between walls, floors,
and ceilings. It may create a safety hazard on floors, steps, and ladders, and
may even collapse ceilings. Accumulations also result in the staining of
ceilings, soffits, and siding, producing unsightly and unsanitary conditions.
Bats also urinate and defecate in
flight, causing multiple spotting and staining on sides of buildings, windows,
patio furniture, automobiles, and other objects at and near entry/exit holes or
beneath roosts. Bat excrement may also contaminate stored food, commercial
products, and work surfaces.
Bat urine readily crystallizes at
room temperature. In warm conditions under roofs exposed to sun and on chimney
walls, the urine evaporates so quickly that it crystallizes in great
accumulations. Boards and beams saturated with urine acquire a whitish powder-like
coating. With large numbers of bats, thick and hard stalactites and stalagmites
of crystallized bat urine are occasionally formed.
Although the fresh urine of a single
bat is relatively odorless, that of any moderate-sized colony is obvious, and
the odor increases during damp weather. Over a long period of time urine may
cause mild wood deterioration (Frantz and Trimarchi 1984). As the urine
saturates the surfaces of dry wood beams and crystallizes, the wood fibers
expand and separate. These fibers then are torn loose by the bats crawling over
such surfaces, resulting in wood fibers being mixed with guano accumulations
underneath.
The close proximity of bat roosts to
human living quarters can result in excreta, animal dander, fragments of
arthropods, and various microorganisms entering air ducts as well as falling onto
the unfortunate residents below. Such contaminants can result in airborne
particles of public health significance.
Bat Echolocation. This is a perceptual system where ultrasonic
sounds are emitted specifically to produce echoes. By comparing the outgoing
pulse with the returning echoes the brain and auditory nervous system can
produce detailed images of the bat's surroundings. This allows bats to detect,
localize and even classify their prey in complete darkness. At 130 decibels in
intensity, bat calls are some of the most intense airborne animal sounds.[17]
To clearly
distinguish returning information, bats must be able to separate their calls
from the echoes they receive. Microbats use two distinct approaches.
1.Low Duty
Cycle Echolocation: Bats can separate their calls and returning echoes in time.
Bats that use this approach time their short calls to finish before echoes
return. This is important because these bats contract their middle ear muscles
when emitting a call to avoid deafening themselves. The time interval between
call and echo allows them to relax these muscles so they can clearly hear the
returning echo. The delay
of the returning echoes provides the bat with the ability to estimate range to
their prey.
2. High Duty
Cycle Echolocation: Bats emit a continuous call and separate pulse and echo in
frequency. The ears of these bats are sharply tuned to a specific frequency
range. They emit calls outside of this range to avoid self-deafening. They then
receive echoes back at the finely tuned frequency range by taking advantage of the Doppler shift of their motion in flight. The Doppler shift of
the returning echoes yield information relating to the motion and location of
the bat's prey. These bats must deal with changes in the Doppler shift due to
changes in their flight speed. They have adapted to change their pulse emission
frequency in relation to their flight speed so echoes still return in the
optimal hearing range.
Two groups
of moths exploit a bat sense to echolocate: tiger moths produce ultrasonic signals to warn the bats that they (the moths)
are chemically protected or aposematic. This was once thought to be the biological
equivalent of "radar jamming", but this theory has yet to be confirmed.
The moths Noctuidae have a hearing organ called a tympanum, which responds to an incoming bat signal by
causing the moth's flight muscles to twitch erratically, sending the moth into
random evasive maneuvers.
Bat Exclusion and Removal. Bats often fly about swimming pools, from
which they drink or catch insects. White light (with an ultraviolet component),
commonly used for porch lights, building illumination, street and parking-lot
lights, may attract flying insects, which in turn attract bats. Unfortunately,
the mere presence of a bat outdoors is sometimes beyond the tolerance of some
uninformed people. Information is a good remedy for such situations.
Bats commonly enter buildings through
openings associated with the roof edge and valleys, eaves, apex of the gable,
chimney, attic or roof vent, dormers, and siding. Other openings may be found
under loose-fitting doors, around windows, gaps around various conduits
(wiring, plumbing, air conditioning) that pass through walls, and through
utility vents.
Bats are able to squeeze through
narrow slits and cracks. For purposes of bat management, one should pay
attention to any gap of approximately 1/4 x 1 1/2 inches (0.6 x 3.8 cm) or a
hole 5/8 x 7/8 inch (1.6 x 2.2 cm). Such openings must be considered potential
entries for at least the smaller species, such as the little brown bat. The
smaller species require an opening no wider than 3/8 inch (0.95 cm), that is, a
hole the diameter of a US 10-cent coin (Greenhall 1982). Openings of these
dimensions are not uncommon in older wood frame structures where boards have
shrunk, warped, or otherwise become loosened.
The discovery of one or two bats in
a house is a frequent problem. In the Northeast, big brown bats probably
account for most sudden appearances (see Figs. 3 and 8). Common in urban areas,
they often enter homes through open windows or unscreened fireplaces. If unused
chimneys are selected for summer roosts, bats may fall or crawl through the
open damper into the house. Sometimes bats may appear in a room, and then
disappear by crawling under a door to another room, hallway, or closet. They
may also disappear behind curtains, wall hangings, bookcases, under beds, into
waste baskets, and so forth. Locating and removing individual bats from living
quarters can be laborious but is important. If all else fails, wait until dusk
when the bat may appear once again as it attempts to find an exit. Since big
brown bats may hibernate in the cooler recesses of heated buildings, they may suddenly appear
(flying indoors or outdoors) in midwinter during a warm spell or a cold snap as
they move about to adjust to the temperature shift.
Rabies and
Other Diseases Associated With Bats.
Rabies is a preventable viral disease of mammals most often
transmitted through the bite of a rabid animal. The vast majority of rabies
cases reported to the Centers for Disease Control and Prevention (CDC) each
year occur in wild animals like raccoons, skunks, bats, and foxes.
The rabies virus infects the central
nervous system, ultimately causing disease in the brain and death. The early
symptoms of rabies in people are similar to that of many other illnesses,
including fever, headache, and general weakness or discomfort. As the disease
progresses, more specific symptoms appear and may include insomnia, anxiety,
confusion, slight or partial paralysis, excitation, hallucinations, agitation,
increased salivation, difficulty swallowing, and hydrophobia (fear of water).
Death usually occurs within days of the onset of these symptoms.
Rabies virus is transmitted through saliva
and brain/nervous system tissue. Only these specific bodily excretions and
tissues transmit rabies virus. If contact with either of these has occurred,
the type of exposure should be evaluated to determine if post-exposure
prophylaxis is necessary. Contact such as petting or handling an animal, or
contact with blood, urine or feces does not constitute an exposure. No
post-exposure prophylaxis is needed in these situations. Rabies virus becomes
noninfectious when it dries out and when it is exposed to sunlight. Different
environmental conditions affect the rate at which the virus becomes inactive,
but in general, if the material containing the virus is dry, the virus can be
considered noninfectious.
Although all species of mammals are
susceptible to rabies virus infection, only a few species are important as
reservoirs for the disease. In the United States, several distinct rabies virus
variants have been identified in terrestrial mammals, including raccoons,
skunks, foxes, and coyotes. In addition to these terrestrial reservoirs,
several species of insectivorous bats are also reservoirs for rabies.
Map
of Terrestrial Rabies Reservoirs in the United States during 2008. Image
Courtesy CDC,
The
only well-documented cases of rabies caused by human-to-human
transmission occurred among eight recipients of transplanted corneas, and among
three recipients of solid organs. Guidelines for acceptance of suitable cornea
and organ donations, as well as the rarity of human rabies in the United
States, reduce this risk.
In addition to transmission from cornea
and organ transplants, bite and non-bite exposures inflicted by infected humans
could theoretically transmit rabies, but no such cases have been documented.
Casual contact, such as touching a person with rabies or contact with
non-infectious fluid or tissue (urine, blood, and feces) does not constitute an
exposure and does not require post exposure prophylaxis.
In
addition, contact with someone who is receiving rabies vaccination does not
constitute rabies exposure and does not require post-exposure prophylaxis.
The first symptoms of rabies may be very
similar to those of the flu including general weakness or discomfort, fever, or
headache. These symptoms may last for days. There may be also discomfort or a
prickling or itching sensation at the site of bite, progressing within days to
symptoms of cerebral dysfunction, anxiety, confusion, agitation. As the disease
progresses, the person may experience delirium, abnormal behavior,
hallucinations, and insomnia. The acute period of disease typically ends after
2 to 10 days. Once clinical signs of rabies appear, the disease is nearly
always fatal, and treatment is typically supportive. Disease prevention
includes administration of both passive antibody, through an injection of human
immune globulin and a round of injections with rabies vaccine.
Once a person begins to exhibit signs of
the disease, survival is rare. To date less than 10 documented cases of human
survival from clinical rabies have been reported and only two have not had a
history of pre- or post-exposure prophylaxis.
. 33. Porcupines are nocturnal animals and active
all year; however, much time is spent resting in trees “called “rest trees”.
34. The best
baits for porcupine traps are “strips of plywood” or other absorbent woods,
cloths, or sponges soaked in salt water.
35. Coyotes will typically bite the throat
just behind the jaw and below the ear when attacking adult sheep or goats, with
death commonly resulting
“from suffocation”.
36. A recent study of 145
ranches where “guard llamas were used” to protect sheep revealed that average
losses of sheep to predators decreased
from 26 to 8 per year after llamas were
employed.
37. The USDA estimates that
total deer damage from “auto collisions” and crop and timber losses reaches at
least $3 billion a year
38. Bats rely on
reflection of “high-pitched squeaks” they emit to avoid collisions and to
determine location of prey.
39. Contact such as petting or handling an animal, or “contact
with blood, urine or feces” does not constitute an exposure to rabies.