Fig. 1. Adult gray wolf,
Two species of wolves
occur in North America, gray wolves (Canis lupus) and
red wolves (Canis rufus). The common names are
misleading since individuals of both species vary in
color from grizzled gray to rusty brown to black. Some
gray wolves are even white. The largest subspecies of
the gray wolf are found in Alaska and the Northwest
Territories of Canada. Adult male gray wolves typically
weigh 80 to 120 pounds (36.3 to 54.4 kg), and adult
females 70 to 90 pounds
(31.8 to 40.8 kg).
Although males rarely exceed 120 pounds (54.4 kg), and
females 100 pounds (45.4 kg), some individuals may weigh
much more. Gray wolves vary in length from about 4.5 to
6.5 feet (1.4 to 2 m) from nose to tip of tail and stand
26 to 36 inches (66 to 91.4 cm) high at the shoulders (Mech
Red wolves are
intermediate in size between gray wolves and coyotes.
Typical red wolves weigh 45 to 65 pounds (20.4 to 29.5
kg). Total length ranges from about 4.4 to 5.4 feet (1.3
to 1.6 m) (Paradiso and Nowak 1972).
Wherever wolves occur,
their howls may be heard. The howl of a wolf carries for
miles on a still night. Both gray wolves and red wolves
respond to loud imitations of their howl or to sirens.
During the 1800s, gray
wolves ranged over the North American continent as far
south as central Mexico. They did not inhabit the
southeastern states, extreme western California, or far
western Mexico (Young and Goldman 1944). In the late
1800s and early 1900s, wolves were eliminated from most
regions of the contiguous United States by control
programs that incorporated shooting, trapping, and
poisoning. Today, an estimated 55,000 gray wolves exist
in Canada and 5,900 to 7,200 in Alaska. In the
contiguous United States, the distribution of the gray
wolf has been reduced to approximately 3% of its
has the largest population of wolves in the lower 48
states, estimated at 1,550 to 1,750. A population of
wolves exists on Isle Royale in Lake Superior, but the
population is at an all-time low of 12 animals. In
recent years, wolves have recolonized Wisconsin, the
Upper Peninsula of Michigan, northwestern Montana,
central and northern Idaho, and northern Washington. A
few isolated gray wolves may also exist in remote areas
Current efforts to
reestablish gray wolves are being conducted in
northwestern Montana, central Idaho, the Greater
Yellowstone area, and northern Washington (USFWS 1987).
Recovery through natural recolonization is likely in
northwestern Montana, central Idaho, and northern
Washington. Due to Greater Yellowstone’s geographic
isolation from areas with established wolf populations,
recovery there would likely require the reintroduction
of wolves into Yellowstone National Park.
Red wolves originally
occurred from central Texas to Florida and north to the
Carolinas, Kentucky, southern Illinois, and southern
Missouri (Young and Goldman 1944). Years of predator
control and habitat conversion had, by 1970, reduced the
range of the red wolf to coastal areas of southeastern
Texas and possibly southwestern Louisiana. When red wolf
populations became low, interbreeding with coyotes
became a serious problem. In the mid1970s, biologists
captured the last few red wolves for captive breeding
before the species was lost to hybridization. The red
wolf was considered extinct in the wild until 1987, when
Red wolf recovery attempts
have been made on Bulls Island near Charleston, South
Carolina, and on Alligator River National Wildlife
Refuge in eastern North Carolina (Phillips and Parker
1988). The Great Smoky Mountains National Park in
western North Carolina and eastern Tennessee is also
being considered as a red wolf reintroduction area. The
goal of the red wolf recovery plan is to return red
wolves to nonendangered status by “re-establishment of
self-sustaining wild populations in at least 2 locations
within the species’ historic range” (Abraham et al.
Gray wolves occupy boreal
forests and forest/agricultural edge communities in
Minnesota, northern Wisconsin, and northern Michigan. In
northwest Montana, northern Idaho, and northern
Washington, wolves inhabit forested areas. In Canada and
Alaska, wolves inhabit forested regions and alpine and
arctic tundra. In Mexico, gray wolves are limited to
remote forested areas in the Sierra Madre Occidental
The last areas inhabited
by red wolves were coastal prairie and coastal marshes
of southeastern Texas and possibly southwestern
Louisiana. These habitats differ markedly from the
diverse forested habitats found over most of the
historic range of red wolves.
Mech (1970) reported that
gray wolves prey mainly on large animals including
white-tailed deer, mule deer, moose, caribou, elk, Dall
sheep, bighorn sheep, and beaver. Small mammals and
carrion make up the balance of their diet. During the
1800s, gray wolves on the Great Plains preyed mostly on
bison. As bison were eliminated and livestock husbandry
established, wolves commonly killed livestock.
Red wolves in southern
Texas fed primarily on small animals such as nutria,
rabbits, muskrats, and cotton rats (Shaw 1975). Carrion,
wild hogs, calves, and other small domestic animals were
also common food items.
General Biology, Reproduction, and Behavior
Gray wolves are highly
social, often living in packs of two to eight or more
individuals. A pack consists of an adult breeding pair,
young of the year, and offspring one or more years old
from previous litters that remain with the pack. The
pack structure of gray wolves increases the efficiency
of wolves in killing large prey. Red wolves may be less
social than gray wolves, although red wolves appear to
maintain a group social structure throughout the year.
Each wolf pack has a home
range or territory that it defends against intruding
wolves. Packs maintain their territories by scent
marking and howling. On the tundra, packs of gray wolves
may have home ranges approaching 1,200 square miles
(3,108 km2). In forested areas, ranges are much smaller,
encompassing 40 to 120 square miles (104 to 311 km2).
Some wolves leave their pack and territory and become
lone wolves, drifting around until they find a mate and
a vacant area in which to start their own pack, or
wandering over large areas without settling. Extreme
movements, of 180 to 551 miles (290 to 886 km), have
been reported. These movements were probably of
dispersing wolves. The home ranges of red wolves are
generally smaller than those of gray wolves. Red wolf
home ranges averaged 27.3 square miles (71 km2) in
southern Texas (Shaw 1975).
Wild gray wolves usually
are sexually mature at 22 months of age. Breeding
usually takes place from early February through March,
although it has been reported as early as January and as
late as April. Pups are born 60 to 63 days after
conception, usually during April or May. Most litters
contain 4 to 7 young.
Courtship is an intimate
part of social life in the pack. Mating usually occurs
only between the dominant (alpha) male and female of the
pack. Thus, only 1 litter will be produced by a pack
during a breeding season. All pack members aid in
rearing the pups.
Dominance is established
within days after gray wolf pups are born. As pups
mature, they may disperse or maintain close social
contact with parents and other relatives and remain
members of the pack.
Little is known about
reproduction in red wolves, but it appears to be similar
to that of gray wolves. Red wolves may breed from late
December to early March. Usually 6 to 8 pups are
Damage and Damage Identification
The ability of wolves to
kill cattle, sheep, poultry, and other livestock is well
documented (Young and Goldman 1944, Carbyn 1983, Fritts
et al. 1992). From 1975 through 1986 an average of 21
farms out of 7,200 (with livestock) in the Minnesota
wolf range suffered verified losses annually to wolves (Fritts
et al. 1992). In more recent years, 50 to 60 farms
annually have been affected by wolf depredations in
Minnesota. Domestic dogs and cats are also occasionally
killed and eaten by gray wolves.
In many instances, wolves
live around livestock without causing damage or causing
only occasional damage. In other instances, wolves prey
on livestock and cause significant, chronic losses at
individual operations. In Minnesota, wolf depredation on
livestock is seasonal, most losses occurring between
April and October, when livestock are on summer
pastures. Livestock are confined to barnyards in the
winter months, and therefore are less susceptible to
Cattle, especially calves,
are the most common livestock taken. Wolves are capable
of killing adult cattle but seem less inclined to do so
if calves are available. Attacks usually involve only
one or two cattle per event. Depredation on sheep or
poultry often involves surplus killing. In Minnesota,
wolf attacks on sheep may leave several (up to 35)
individuals killed or injured per night. Attacks on
flocks of domestic turkeys in Minnesota have resulted in
nightly losses of 50 to 200 turkeys.
Wolf attacks on livestock
are similar to attacks on wild ungulates. A wolf chases
its prey, lunging and biting at the hindquarters and
flanks. Attacks on large calves, adult cattle, or horses
are characterized by bites and large ragged wounds on
the hindquarters, flanks, and sometimes the upper
shoulders (Roy and Dorrance 1976). When the prey is
badly wounded and falls, a wolf will try to disembowel
the animal. Attacks on young calves or sheep are
characterized by bites on the throat, head, neck, back,
or hind legs.
Wolves usually begin
feeding on livestock by eating the viscera and
hindquarters. Much of the carcass may be eaten, and
large bones chewed and broken. The carcass is usually
torn apart and scattered with subsequent feedings. A
wolf can eat 18 to 20 pounds (8.1 to 9 kg) of meat in a
short period. Large livestock killed by wolves are
consumed at the kill site. Smaller livestock may be
consumed at the kill site in one or two nights or they
may be carried or dragged a short distance from the kill
site. Wolves may carry parts of livestock carcasses back
to a den or rendezvous sites. Wolves may also carry off
and bury parts of carcasses.
Wolves and coyotes may
show similar killing and feeding patterns on small
livestock. Where the livestock has been bitten in the
throat, the area should be skinned out so that the size
and spacing of the tooth holes can be examined. The
canine tooth holes of a wolf are about 1/4 inch (0.6 cm)
in diameter while those of a coyote are about 1/8 inch
(0.3 cm) in diameter. Wolves usually do not readjust
their grip in the throat area as coyotes sometimes do;
thus, a single set of large tooth holes in the throat
area is typical of wolf depredation. Coyotes will more
often leave multiple tooth holes in the throat area.
Attacks on livestock by
dogs may be confused with wolf depredation if large
tracks are present, especially in more populated areas.
Large dogs usually injure and kill many animals. Some
dogs may have a very precise technique of killing, but
most leave several mutilated livestock. Unless they are
feral, they seldom feed on the livestock they have
Wolves are attracted to
and will scavenge the remains of livestock that have
died of natural causes. Dead livestock in a pasture or
on range land will attract wolves and increase their
activity in an area. It is important to distinguish
between predation and scavenging. Evidence of predation
includes signs of a struggle and hemorrhaging beneath
the skin in the throat, neck, back, or hindquarter area.
Tracks left by wolves at
kill sites are easily distinguishable from those of most
other predators except large dogs. Wolf tracks are
similar to coyote tracks but are much larger and reveal
a longer stride. A wolf’s front foot is broader and
usually slightly longer than its rear foot. The front
foot of the Alaskan subspecies is 4 to 5 inches (10.2 to
12.7 cm) long (without claws) and 3 3/4 to 5 inches (9.5
to 12.7 cm) wide; the rear foot is 3 3/4 to 4 3/4 inches
(9.5 to 12.1 cm) long and 3 to 4 1/2 inches (7.6 to 11.4
cm) wide (Murie 1954) (Fig. 3). Track measurements of
the eastern subspecies of gray wolf found in Minnesota
and Wisconsin are slightly smaller. The distance between
rear and front foot tracks of a wolf walking or trotting
on level ground varies between 25 and 38 inches (63.5 to
96.5 cm). When walking, wolves usually leave tracks in a
straight line, with the rear foot prints overlapping the
front foot prints. In deep snow, wolves exhibit a
single-file pattern of tracks, with following wolves
stepping in the tracks of the leading wolf.
Fig. 3. Gray wolf and coyote silhouettes and track
measurements of each.
Wolf tracks are similar to
the tracks of some large breeds of dogs but are
generally larger and more elongated, with broader toe
pads and a larger heel pad. Dog tracks are rounder than
wolf tracks, and the stride is shorter. When walking,
dogs leave a pattern of tracks that looks
straddle-legged, with the rear prints tending not to
overlap the front prints. Their tracks appear to wander,
in contrast to the straight-line pattern of wolf tracks.
Scats (droppings) left in
the vicinity of a kill site or pasture may be useful in
determining wolf depredation. Wolf scats are usually
wider and longer than coyote scats. Scats 1 inch (2.5
cm) or larger in diameter are probably from wolves;
smaller scats may be from wolves or coyotes. Wolf scats
frequently contain large amounts of hair and bone
fragments. An analysis of the hair contained in scats
may indicate possible livestock depredation. Since
wolves feed primarily on big game, their scats are not
as likely to contain the fine fur or the small bones and
teeth that are often found in coyote scats.
During hard winters, gray
wolves may contribute to the decline of populations of
deer, moose, and caribou in northern areas (Gauthier and
Theberge 1987). Studies in Minnesota (Mech and Karns
1977), Isle Royale (Peterson 1977), and Alaska (Gasaway
et al. 1983, Ballard and Larsen 1987) indicate that
predation by wolves, especially during severe winters,
may bring about marked declines in ungulate populations.
It appears that after ungulate populations reach low
levels, wolves may exert long-term control over their
prey populations and delay their increase.
All gray wolves in the
contiguous 48 states are classified as “endangered”
except for members of the Minnesota population, which
are classified as “threatened.” The maximum penalty for
illegally killing a wolf is imprisonment of not more
than 1 year, a fine of not more than $20,000, or both.
The classification of the wolf in Minnesota was changed
from “endangered” to “threatened” in April 1978. This
classification allows a variety of management options,
including the killing of wolves that are preying on
livestock by authorized federal or state personnel. In
Canada and Alaska, gray wolves are considered both
furbearers and game animals and are subject to sport
harvest and control measures regulated by province or
Red wolves are classified
as “endangered” in the United States. This
classification restricts control of red wolves to
authorized federal or state damage control personnel,
who may capture and relocate red wolves that are preying
Prevention and Control Methods
Fences may help prevent
livestock losses to wolves. Exclude wolves with
well-maintained woven-wire fences that are 6 to 7 feet
(1.8 to 2.1 m) high. Install electrically charged wires
along the bottom and top of woven-wire fences to
increase their effectiveness. Several antipredator
fencing designs are available (Thompson 1979, Dorrance
and Bourne 1980, Linhart et al. 1984).
Livestock carcasses left
in or near pastures may attract wolves and other
predators to the area and increase the chances of
depredation. Remove and properly dispose of all dead
livestock by rendering, burying, or burning.
Calves and lambs are
particularly vulnerable to predators, and cows are
vulnerable while giving birth. Confine cows and ewes to
barnyard areas during calving and lambing season if
possible or maintain them near farm buildings. Hold
young livestock near farm buildings for 2 weeks or
longer, before moving them with the herd to pastures or
rangeland. As newborns mature they are better able to
stay with their mothers and the herd or flock, and are
less likely to be killed by wolves.
Nighttime losses of sheep
to wolves can be reduced by herding the sheep close to
farm buildings at night or putting them in pens where
If wolf depredation is
suspected, livestock producers should observe their
livestock as often as possible. Frequent observation may
be difficult in large wooded pastures or on large tracts
of open rangeland. The more often livestock are checked,
however, the more likely that predation will be
discovered. Frequent checks will also help the operator
determine if any natural mortality is occurring in the
herd or flock, and if any livestock thought to be
pregnant are barren and not producing. The presence of
humans near herds and flocks also tends to decrease
Livestock guarding dogs
have been used for centuries in Europe and Asia to
protect sheep and other types of livestock. The dogs are
bonded socially to a particular type of livestock. They
stay with the livestock without harming them and either
passively repel predators by their presence or chase
predators away. Livestock guarding dogs are currently
being used by producers in the western United States to
protect sheep and other livestock from coyotes and
bears. They have been used in Minnesota to protect sheep
from coyotes and cattle from wolves. The most common
breeds of dogs used in the United States are the
Anatolian shepherd, Great Pyrennees, Komondor, Akbash
dogs, Kuvasz, Maremma, and Shar Plainintez. Livestock
guarding dogs should be viewed as a supplement to other
forms of predator control. They usually do not provide
an immediate solution to a predator problem because time
must be spent raising puppies or bonding the dogs to the
livestock they protect. Green et al. (1984) and Green
and Woodruff (1990) discuss proper methods for selecting
and training livestock guarding dogs and reasonable
expectations for effectiveness of guarding dogs against
predators. Consult with USDA-APHIS-ADC personnel for
Strobe light/siren devices
(Electronic Guard [USDA-APHIS-ADC]) may be used to
reduce livestock depredation up to 4 months. Such
devices are probably most effective in small, open
pastures, around penned livestock, or in situations
where other lethal methods may not be acceptable. They
can also provide short-term protection from wolves while
other control methods are initiated.
None are registered for
wolves in the United States.
None are registered for
wolves in the United States.
Control of damage caused
by wolves is best accomplished through selective
trapping of depredating wolves. Another method is to
classify wolves as furbearers and/or game animals and
encourage sport harvest to hold wolf populations at
acceptable levels. The Alberta Fish and Wildlife
Division has used this approach successfully in Canada,
where gray wolves are classified as furbearers. A
similar approach was proposed by the Minnesota
Department of Natural Resources in 1980 and 1982 to help
control the expanding wolf population in Minnesota, but
it was ruled illegal because of the wolf’s “threatened”
status in Minnesota.
Steel leghold traps, Nos.
4, 14, 114, and 4 1/2 Newhouse or Nos. 4 and 7 McBride
are recommended for capturing wolves. Nos. 4 and 14
Newhouse traps and the No. 4 McBride trap are routinely
used for research and depre-dation-control trapping of
wolves in Minnesota. Some wolf trappers feel that Nos. 4
and 14 Newhouse traps are too small for wolves. Where
larger subspecies of the gray wolf exist, use the No. 4
1/2 Newhouse, No. 7 McBride, or the Braun wolf trap.
Set traps at natural scent
posts where wolves urinate and/or defecate along their
travel routes. Make artificial scent posts by placing a
small quantity of wolf urine, lure, or bait on weeds,
clumps of grass, low bushes, log ends, or bones located
along wolf travel routes. Place traps near the carcasses
of animals killed or scavenged by wolves, at trail
junctions, or at water holes on open range. Set snares
(Thompson 4xx or 5xx, Gregerson No. 14) at holes in or
under fences where wolves enter livestock confinement
areas, or where wolves create trails in heavy cover.
Use traps and snares that
are clean and free of foreign odor. Remove grease and
oil from new traps and snares, set them outside until
slightly rusted, and then boil them in a solution of
water and logwood trap dye. Wear gloves when handling
traps and snares to minimize human odor. While
constructing the set, squat or kneel on a clean canvas
“setting cloth” to minimize human odor and disturbance
at the site. Traps may be either staked or attached to a
draghook. A trap that is staked should have about 4 feet
(1.2 m) of chain attached to it. A trap with a draghook
should have 6 to 8 feet (1.8 to 2.4 m) of chain
Where legal, local wolf
populations can be reduced by shooting. Call wolves into
rifle range using a predator call or by voice howling.
Aerial hunting by
helicopter or fixed-wing aircraft is one of the most
efficient canid control techniques available where it is
legal and acceptable to the general public. Aerial
hunting can be economically feasible when losses are
high and the wolves responsible for depredation can be
taken quickly. When a pack of wolves is causing damage,
it may be worthwhile to trap one or two members of the
pack, outfit them with collars containing radio
transmitters and release them. Wolves are highly social
and by periodically locating the radiotagged wolves with
a radio receiver, other members of the pack may be found
and shot. The wolves wearing radio collars can then be
located and shot. This technique has been used
effectively by the Alaska Department of Fish and Game.
In situations where lethal
control of depredating wolves may not be authorized (USFWS
1987), aerial hunting by helicopter can be used to dart
and chemically immobilize depredating wolves so that
they can be relocated from problem areas. Some recent
wolf control actions in Montana have used this
planning should solve most conflicts between livestock
producers and wolves. When wolves are present in the
vicinity of livestock, predation problems are likely to
develop. Therefore, care should be taken in selecting
areas for reestablishing wolf populations to assure that
livestock production will not be threatened by wolves.
Economics of Damage and
Control Wolves can sometimes cause serious economic
losses to individual livestock producers. Minnesota,
Wisconsin, and Montana have established compensation
programs to pay producers for damage caused by wolves.
In recent years, $40,000 to $45,000 has been paid
annually to Minnesota producers for verified claims of
wolf damage. Control of depredating wolves is often
economically feasible, but it can be time-consuming and
labor intensive. If wolves can be trapped, snared, or
shot at depredation sites, the cost is usually low.
Deer, moose, and other
ungulates have great economic and aesthetic value, but
wolves have strong public support. Thus, wolf control is
often highly controversial. Where wolves are the
dominant predator on an ungulate species and prey
numbers are below carrying capacity, a significant
reduction in wolf numbers can produce increases in the
number of ungulate prey (Gasaway et al 1983, Gauthier
and Theberge 1987) and therefore sometimes can be
economically justified. When control programs are
terminated, wolves may rapidly recover through
immigration and reproduction (Ballard et al. 1987).
Therefore, wolf control must be considered as an
acceptable management option (Mech 1985).
Information contained in
the sections on identification, habitat, food habits,
and general biology are adapted from Mech (1970). The
Methods of Investigating
Predation of Domestic Livestock, by Roy and Dorrance was
very helpful in developing the section on wolf damage
identification. Recommendations for preventing or
reducing wolf damage were developed in association with
Dr. Steven H. Fritts. We would also like to thank Scott
Hygnstrom for reviewing this chapter and providing many
Figure 1 from Schwartz and
Figure 2 adapted from
Schwartz and Schwartz (1981) by Jill Sack Johnson.
Figure 3 adapted from a
Michigan Department of Natural Resources pamphlet.
For Additional Information
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Ballard, W. B., J. S.
Whitman, and C. L. Gardner. 1987. Ecology of an
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Bourne. 1980. An evaluation of anti-coyote electric
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L. D. Mech, and D. P. Scott. 1992. Trends and management
of wolf-livestock conflicts in Minnesota. US Fish Wildl.
Serv. Resour. Publ. 181., Washington, DC. 27 pp.
Gasaway, W. C., R. O.
Stephenson, J. L. David, P. K. Shepherd, and O. E.
Burris. 1983. Interrelationships of wolves, prey, and
man in interior Alaska. Wildl. Mono. 84. 50 pp.
Gauthier, D. A., and J. B.
Theberge. 1987. Wolf predation. Pages 120-127 in M.
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Green, J. S., and R. A.
Woodruff. 1990. Livestock guarding dogs: protecting
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Woodruff, and T. T. Tueller. 1984. Livestock guarding
dogs for predator control: costs, benefits, and
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Linhart, S. B., J. D.
Roberts, and G. J. Dasch. 1982. Electric fencing reduces
coyote predation on pastured sheep. J. Range Manage.
Linhart, S. B., R. T.
Sterner, G. J. Dasch, and J. W. Theade. 1984. Efficacy
of light and sound stimuli for reducing coyote predation
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Murie, O. J. 1954. A field
guide to animal tracks. The Riverside Press, Cambridge,
Massachusetts. 374 pp.
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Nowak. 1972. A report on the taxonomic status and
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Thompson, B. C. 1979.
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Young, S. P., and E. A.
Goldman. 1944. The wolves of North America. Parts 1 and
2. Dover Publ. Inc., New York. 636 pp.
Scott E. Hygnstrom Robert
M. Timm Gary E. Larson
PREVENTION AND CONTROL OF
WILDLIFE DAMAGE — 1994
Division Institute of Agriculture and Natural Resources
University of Nebraska -Lincoln
United States Department
of Agriculture Animal and Plant Health Inspection
Service Animal Damage Control
Great Plains Agricultural
Council Wildlife Committee