Eric M. Gese 

Research Wildlife Biologist 

USDA-APHIS-Wildlife Services 

National Wildlife Research Center 

Logan, Utah

John P. Hart 

District Supervisor

USDA-APHIS-Wildlife Services 

Grand Rapids, Minnesota

Patricia A. Terletzky 

Geospatial Analyst

Department of Wildland Resources

Utah State University

Logan, Utah

 

Human-Wildlife Conflicts

The gray wolf (Canis lupus) is a wideranging carnivore with a global 

distribution throughout the northern 

hemisphere. Wolves are the largest 

member of the family Canidae (Figure 1). 

It is often considered a symbol of the 

wilderness.

Historically, wolves were found throughout 

North America. By the 1940s, however, 

wolves were eradicated from most of their 

former range in the continental United 

States. Gray wolves were listed as an 

endangered species in 1974. Subsequent 

recovery efforts have resulted in wolf 

populations in the western Great Lakes 

Region, the northern Rocky Mountains, the 

southwest (Mexican wolf), and the Pacific 

Northwest.

Wolf conflicts are primarily related to 

predation on livestock, pets and other 

domestic animals, as well as their direct 

and indirect impacts on native 

Wildlife Damage Management 

Technical Series

U.S. Department of Agriculture

Animal & Plant Health Inspection Service

Wildlife Services

May 2021 Gray Wolves

Figure 1. Gray wolf (Canis lupus).

Quick Links

Human-Wildlife Conflicts 1

Damage Identification 4

Management Methods 6

Economics 16

Species Overview 19

Legal Status 22

Glossary & Keywords 23

Resources 24

Appendix 29
ungulates (i.e., big game). Economic losses vary 

widely with some livestock producers facing high 

levels of depredation in some areas. 

This publication focuses on wolf ecology, damage, and 

management, particularly as it relates to wolf 

depredation on livestock and other conflicts with 

people. 

Human Health and Safety

Wolves and people share the same environments 

more than people realize. In the U.S., wolves are not 

confined to wilderness areas. Though curious, wolves 

generally fear people and rarely pose a threat to 

human safety. Wolf attacks on people are, and always 

have been, very rare compared to other wildlife 

species. However, there have been several cases of 

human injuries and a few deaths due to wolves in 

North America over the past 100 years. The main 

factors contributing to these incidents were 

habituation to people, rabies infections, conditioning 

to human foods, and the presence of domestic dogs.

It is unusual for wild wolves to associate or interact 

with people, linger near buildings, livestock, or 

domestic dogs, but it does occur especially in areas of 

high wolf densities in and around rural communities. 

This type of behavior may be more prevalent in areas 

where wolves are not legally harvested. This “bold” 

behavior is more typical of a habituated or foodconditioned animal, a released captive wolf, or a 

released wolf-dog hybrid. Wolves are sometimes 

attracted to human settlement because of high prey 

densities (e.g., deer) or other items, such as livestock 

carcasses or bone piles.

The effects of epizootics and enzootics on wolf 

populations are not well documented. The 

transmission of diseases, such as canine parvovirus, 

from domestic dogs to wild wolves is a conservation 

concern. Rabies is a human health concern but is 

infrequently reported in wolves. However, it may have 

been a cause for attacks on people in European 

history. Wolves are hosts to various protozoans and 

parasites, including the hydatid worm, Echinococcus 

granulosus. It can be transmitted to people and grows into 

a tapeworm in its host.

Livestock Depredation

The scale and scope of wolf depredation on livestock 

depends on local wolf density; numbers and kinds of 

livestock; livestock husbandry practices; availability and 

vulnerability of alternative prey; human density; road 

density; severity of winters; and local hunting pressure.

In many instances, wolves live around livestock without 

causing damage or only occasional damage. Wolf pack 

size has been shown to increase the likelihood of 

depredations on domestic animals, with larger packs 

more likely to cause damage. Most losses occur 

between April and October when livestock are on 

summer pastures or grazing allotments. Cattle, 

especially calves, are the most common livestock killed 

by wolves. When wolves kill sheep or domestic poultry, 

often multiple individuals are killed or injured.

The number of complaints and depredations on 

domestic livestock varies by state. For example, in 

Montana, the number of suspected and verified 

complaints of wolf damage to livestock steadily 

increased following the reintroduction of wolves to the 

northern Rocky Mountains in 1995. Then after 2010, 

when the state began a legal harvest and trapping 

season on wolves, wolf depredations declined and 

plateaued at a lower level (Figure 2). Similarly, in 

Minnesota where wolves were not extirpated and 

recovered naturally after federal protection, the wolf 

population, their geographic range, and depredations 

on livestock increased steadily in the 1990’s, but has 

remained relatively stable over the past 20 years as the 

wolf population size and range has stabilized (Figure 3). 

In Minnesota, only 1 to 2% of livestock operations in 

wolf range are impacted by verified wolf depredations 

annually. It is important to note, however, that losses 

can be significant to individual producers or producers 

located in the same region in given years.

Page 2 WDM Technical Series─Gray Wolves
Figure 2. Number of suspected and verified wolf depredation complaints received by the U.S. Department of Agriculture’s Wildlife

Services program in Montana, 1997—2017.

U.S. Department of Agriculture Page 3

Figure 3. Mid-winter population size of wolves in Minnesota, 1989-2018.
Guarding Animals and Pets

In addition to livestock depredation, wolves sometimes 

kill and injure domestic pets and livestock guarding 

animals, such as livestock protection dogs (LPD) and 

donkeys.

Wolf attacks on domestic pets (mostly dogs), have 

increased as wolf numbers have increased in the lower 48 

states. Many attacks on domestic dogs seem to be 

triggered by territorial behavior where wolves view dogs as 

canine competitors. In such cases, the dogs are often 

killed or injured. Only occasionally are they fed upon. While 

generally, there is no compensation for these losses of 

pets, some state damage management boards are now 

compensating for the loss of livestock protection dogs 

(LPD). People residing in wolf country should be aware of 

the vulnerability of their pets and keep them near their 

residence or have fencing to contain their pets and 

exclude wolves.

For decades, LPDs have helped protect livestock from 

coyotes, feral dogs, foxes, and mountain lions in the U.S. 

However, some of the dog breeds currently used to protect 

livestock from coyotes are no match for larger predators, 

such as wolves and grizzly bears. Recent research has 

investigated the use of larger European dog breeds to 

protect livestock from wolves.

Natural Resources

As a keystone species, wolves play a critical role in 

ecosystem dynamics and the regulation of native 

ungulate populations. Wolves are large-bodied carnivores 

that primarily prey upon large herbivores, with prey 

species varying by location. For example, elk and deer are 

more plentiful in the northern Rocky Mountains and are 

the primary prey of wolves in that region, while moose 

and deer are more commonly available and preyed upon 

in the Great Lakes region.

The impact that wolves have on native ungulate species 

is highly variable and dependent on a multitude of 

factors. For example, in what might at first appear to be a 

relatively simple ecosystem of one prey and one predator, 

the relationship between wolves and moose on Isle 

Royale remains ambiguous. Results of almost 60 years of 

study show the dynamics between wolves and moose to 

be a complex interaction of disease, genetics and 

inbreeding, and food limitations all contributing to 

changes in wolf and moose abundance on this island 

ecosystem. 

In the northern Rocky Mountains where several areas 

contain multiple prey species and multiple predators, the 

interactions in this complex ecosystem is even more 

difficult to predict. The presence of wolves, grizzly bears, 

and cougars preying on elk, deer, and moose, makes 

predicting or elucidating the causes responsible for 

declines as well as increases in ungulate populations 

difficult. In some areas, ungulate abundance has 

declined in the face of predation combined with human 

hunting. While in other areas, elk abundance is over 

population objective as identified by state wildlife 

agencies. Multiple factors, including predation, winter 

severity, human hunting pressure on both prey and 

predators, interspecific competition among predators and 

prey species, and changing landscapes via habitat loss 

and fragmentation, all contribute to the complexity and 

difficulty of determining cause and effect in changing 

dynamics and abundance of ungulate populations. 

Damage Identification

Wolves prey mainly on wild ungulates, such as deer, 

caribou, moose, and elk. Cattle, especially calves, and 

domestic sheep are also vulnerable to wolf predation. 

While predation on livestock is not as common as 

predation on wild ungulates, wolf predation on cattle and 

sheep has been increasing in the lower 48 states as wolf 

populations increase.

Wolves are not the only predator species that kill 

livestock. Other predators besides wolves include 

coyotes, domestic dogs, black bear, grizzly bear and 

mountain lions. In the northern Rocky Mountains, it is 

common for grizzly bears to displace wolves from a 

carcass making it difficult to ascertain what species 

Page 4 WDM Technical Series─Gray Wolves
actually killed the animal. It is important to accurately 

identify the species responsible in order to select the 

most appropriate methods and techniques to use in an 

integrated damage management program. Tracks and 

scats found at a depredation site are often used in 

conjunction with the killing and feeding pattern found 

on a carcass to determine the predator involved.

Wolf Depredation Signs

Wolves usually kill ungulates by attacking the 

hindquarters or by seizing the flanks. Wolves often bite 

mid-sized calves (100 to 250 pounds (lbs)/45 to 115 

kilograms (kg)) over the top of the back between the 

rear of the ribs and the pelvis. Sometimes their canine 

teeth penetrate the body cavity with this bite and 

sometimes the bite is strong enough to separate the 

vertebrae.

Slash marks made by the canine teeth may be found on 

the rear legs and flanks. When the victim is badly 

wounded, wolves will often disembowel the animal. 

Wolves usually eat the viscera (internal organs) and 

hindquarters first.

Wolf kills are characterized by massive trauma, and 

large tooth marks may not be visible until the animal is 

skinned or partially skinned during a depredation 

investigation. Large bones may be chewed or cracked 

open. Wolves may carry or drag parts of the carcass to 

nearby vegetative cover, dens or rendezvous sites for 

the young to consume. Generally, most of the carcass is 

eaten (Figure 4), sometimes over the course of multiple 

feedings. Occasionally, feeding is interrupted by other 

livestock, especially the mother cow, or by the producer.

Wolves readily scavenge dead livestock, thus wolves 

found feeding on a livestock carcass or having livestock 

hair in their scat may not have killed the animal.

Coyote Versus Wolf Depredation Signs

Wolf and coyote damage can overlap with depredations 

occurring on the same property and within days of each 

other. Coyotes normally kill livestock with bites to the 

neck and throat, but may pull the animal down by 

attacking the side and hindquarters. Young calves may 

be bitten in the flanks, and entrails eaten, destroying 

any discernable evidence of predation at the site of the 

attack. The rumen (first stomach) and intestines of 

sheep are generally not eaten, but are often removed 

and dragged away from the carcass. When coyotes kill 

small lambs, their upper canine teeth often penetrate 

the top of the neck or the skull.

Calf predation by coyotes is most common when calves 

are young. Calves attacked, but not killed, exhibit 

U.S. Department of Agriculture Page 5

Figure 4. Wolf predation on domestic livestock often results in most of the carcass being consumed.
Page 6 WDM Technical Series─Gray Wolves

wounds to the flank, hindquarters, or front shoulder. 

Coyotes generally have a lighter feeding pattern (they do 

not completely dismember the carcass and crush all the 

long bones) than wolves, and often the carcasses of 

calves or ewes are still intact, with entrails and meat 

eaten. Coyotes will return to carcasses for multiple 

feedings, scavenge on wolf kills, and at times, multiple 

coyotes (often family groups), can consume large amounts 

of meat, making it difficult to distinguish between coyote 

and wolf depredations.

Domestic Dog Versus Wolf Depredation Signs

Depredation by domestic dogs also can be confused with 

wolf or coyote kills. Domestic dogs can be a serious 

problem to livestock, especially to sheep pastured near 

cities and suburbs. Dogs vary how and where they 

attack, but often attack the hindquarters, flanks, and 

head. They rarely kill as effectively as wolves or coyotes 

and are considered “sloppy” predators, slashing and 

tearing prey that sometimes results in many injured 

animals. Dogs generally wound animals in the neck and 

front shoulders; the ears often are badly torn. Skinning 

the carcass often reveals bruises on 80% of the body 

due to bites that did not penetrate the skin. Dogs rarely 

feed on the carcass. If dogs eat sheep or big game, they 

normally eat the thighs and rear end and often vomit 

near the site.

Management Methods

Responsible and professional reduction or elimination of 

wildlife damage is the goal of wildlife damage management 

practitioners. This is best accomplished through an 

integrated approach. No single method is effective in every 

situation, and success is optimized when damage 

management is initiated early, consistently, and adaptively 

using a variety of methods. Because the legality of 

methods vary by state, consult local laws and regulations 

prior to the implementation of any method. 

For a summary table of wolf management methods, please 

see the Appendix. 

Animal Husbandry

Animal husbandry includes a variety of activities related to 

the care and attention given to livestock. Generally, when 

the frequency and intensity of livestock husbandry 

increases, so does the degree of protection from 

predators. 

Various animal husbandry practices can reduce 

depredation losses by wolves. Some of the most common 

include: 

• confining or concentrating herds/flocks during periods 

of vulnerability (e.g., at night or during lambing), 

• using herders or “range riders” (Figure 5),

• shed lambing,

• synchronizing birthing,

• keeping young animals in areas with little vegetative 

cover and in close proximity to human activity, and

• properly disposing of livestock carcasses by rendering, 

burying, composting, or burning to discourage 

scavenging by wolves. 

Figure 5. The use of range riders (a person patrolling a range on horseback) is 

growing in popularity in many areas with wolves. They help to deter wolves and assist 

in herd management. 
These practices generally require additional resources 

and effort, and may only delay the onset of predation, or 

may have undesirable side effects (e.g., night penning 

requires added effort and frequently causes spot 

deterioration of pastures, or shed lambing requires 

added labor and feed costs). For these methods to be 

effective, producers must develop and adapt strategies 

to fit their unique situations. Although the economic 

advantages of modifying husbandry practices may be 

difficult to quantify, the changes can assist in herd 

management and production (e.g., range riders often 

find calves that may have been abandoned or are in 

distress).

Birthing Pens

Birthing pens are a form of temporary or permanent 

fencing where cows or ewes are given extra protection 

during a vulnerable time. Non-protected birthing on the 

open range is not recommended in wolf country. Not 

only are birthing animals and their newborn calves or 

lambs extremely vulnerable to depredation during and 

immediately following birth, but the blood and afterbirth 

can be strong attractants to all types of predators. The 

effectiveness of birthing pens and/or night pens can be 

enhanced with fladry or turbo-fladry (described below).

Night Penning

Bringing livestock herds or flocks into paddocks or 

pens at night can help to reduce wolf depredations. 

Night penning may require a period of adjustment 

and the help of herding dogs, as livestock become 

used to being gathered together at night. Eventually, 

the animals head for the night pens willingly. An 

added benefit of night penning is that producers are 

able to monitor the health of the herd and individual 

animals on a regular basis.

Biofence

A “biofence” is a type of biological barrier that uses 

artificial scent-marks (e.g., feces and urine) to exploit 

the territorial behavior of predators. This concept 

originated in Botswana to keep African wild dogs 

(Lycaon pictus) from leaving protected reserves and 

entering farmlands to depredate livestock. However, 

biofences have had limited success in altering wolf 

pack movements and are not really considered an 

effective management technique for wolves 

depredating livestock. Wolves may habituate to a 

biofence more quickly without the occasional physical 

confrontation at territorial borders necessary to 

reinforce territory boundaries among wolves.

Electronic Training Collar

Electronic training collars are a nonlethal method for 

deterring wolf predation by potentially changing a wolf’s 

behavior during a predation attack (Figure 6). They are 

similar to shock collars used to train domestic dogs. 

Studies have shown that wolves with electronic collars 

avoided bait sites more than wolves without collars. 

Collared wolves also moved further away from bait 

stations after being shocked. However, the avoidance 

behavior did not continue once shocking ceased. 

Investigators note that electronic collars may have limited 

field applicability since they require the capture and 

handling of wolves in order to attach the collars or change 

the collar’s batteries. Also, non-collared wolves 

U.S. Department of Agriculture Page 7

Figure 6. Electronic training collar used to shock a collared wolf 

when it enters a designated area. Requires capture and 

placement of the collar on the wolf. 
Page 8 WDM Technical Series─Gray Wolves

are not affected and may still cause damage. Although 

this document provides information on this technique, it 

likely is not a practical solution for managing depredation 

problems. However, if costs and labor are not an issue 

and these collars are used, the receiver could be tuned 

to communicate with the collar at a distance equal to the 

width of the pasture or area containing the stock needing 

protection. Having a radio-collared wolf with the training 

collar could then be triggered when the radio-collar is 

detected within the range of the receiver.

Exclusion

Effective barriers for excluding wolves from livestock 

include wire fences, fladry or turbo- fladry. 

Fencing

Wolves may be excluded from pastures with wellmaintained woven-wire fences that are 6 to 7 feet (ft) (2 

to 2.5 meters (m)) high. However, many factors, 

including the density, behavior and motivation of wolves, 

terrain and vegetative conditions, availability of prey, size 

of pastures, and time of year, as well as the fence design, 

construction, and maintenance, will impact the overall 

effectiveness of a fence.

Adding an electrified single-wire strand charged by a 

commercial fence charger to the woven-wire fence can 

increase its effectiveness. The electrified wire should 

be placed 8 inches (20 centimeters (cm)) outside of the 

main fence line and 8 inches (20 cm) above the 

ground.

Additionally, a 5 ft (1.5 m) woven-wire fence with 9 to 12 

alternating ground and charged wires spaced 4 to 6 

inches (10 to 15 cm) apart is an effective barrier against 

coyotes, and may be effective against wolves. A hightensile woven-wire fence is more versatile, longer 

lasting, and can be tightened more than a conventional 

wire mesh fence.

It is unlikely that fences will totally exclude all wolves from 

an area, however, fences can increase the effectiveness of 

other damage management methods, such as penning 

livestock, using guard animals, and trapping. For example, 

the combined use of LPDs and fencing may be more 

successful than either method alone. Installation costs 

usually preclude the use of fences for protecting 

livestock in large pastures or under range conditions.

Approximately 52% of surveyed livestock producers 

use fencing to exclude predators from sheep and 

lambs.

Figure 7. A corral of fladry erected on a grazing allotment in Idaho for night-penning sheep (left), and fladry being set-up on a farm in Minnesota (right). 
Fladry

Fladry consists of polypropylene cording or similar 

material on which red or orange cloth flagging or plastic 

vinyl taping is hung at 18-inch (46 cm) intervals and 

strung on temporary or permanent fence posts (Figure 

7). First used in Europe to surround wolves in order to 

hunt them, fladry has been adapted for use as a 

nonlethal wolf deterrent. Because carnivores are often 

wary of new items in their environment (like fluttering 

flags), they are cautious about crossing the fladry 

barrier.

Turbo-fladry is similar to fladry but is strung on electric 

fencing material, often PVC-coated for durability. Turbofladry combines the effectiveness of fladry with the shockdelivering power of an electric fence. If a wolf overcomes 

its innate fear of the flagging and attempts to pass the 

fladry barrier, a shock is delivered. The added “shock 

value” of the turbo-fladry appears to enhance the 

avoidance time for wolves.

Both types of fladry are recommended for temporary use, 

such as on calving or lambing areas, and are typically 

effective for 90 to 120 days.

Fladry and turbo-fladry are easy to install. A number of 

producers have developed bagging systems for fladry or 

reels that can fit on the back of a pickup, ATV, or saddle for 

easy and rapid installation. Fiberglass poles can be carried 

and quickly installed with a hammer or sleeve driver. The 

fladry can be strung through the metal clips normally used 

with such poles. Turbo-fladry is generally powered by golfcart or marine batteries that are recharged using solar 

panels.

As part of a collaboration between the Defenders of 

Wildlife and USDA Wildlife Services, the combined use of 

fladry, LPDs, and herders has effectively deterred wolf 

predation on sheep in Idaho while limiting the need to 

remove wolves from the area.

Fertility Control

Currently, there are no fertility control products registered 

for use with wolves. Vasectomy of male wolves has been 

proposed as a method to manage populations, but has not 

been tested and may be impractical or economically 

infeasible. While not tested on wolves, sterilized coyotes 

killed significantly less domestic sheep than intact coyotes.

Frightening Devices

Lights, distress calls, loud noises, scarecrows, 

plastic streamers, propane cannons, aluminum pie 

pans, and lanterns have been used to frighten 

predators. While all of these devices can provide 

temporary relief from predator damage, wolves may 

quickly habituate to them. Changing the location of 

devices, the pattern of the disruptive-stimuli or 

combining several techniques prolongs the 

frightening effect. One research study suggests that 

light may be the most important component of a 

frightening device.

Devices developed to deter wolf predation and prevent

habituation include the Radio Activated Guard (RAG) box 

(Figure 8) and the Movement Activated Guard (MAG) 

device. The RAG box is triggered and emits lights and 

U.S. Department of Agriculture Page 9

Figure 8. A Radio-Activated Guard (RAG) box consisting of a radio-telemetry receiver 

that activates the unit when a radio-collared wolf is detected. Unit consists of strobe 

lights, solar-powered battery, user defined activation distance, and plays more than 

30 different sounds to scare the wolf away. 
Page 10 WDM Technical Series─Gray Wolves

sounds when a radio-collared wolf comes within a 

predetermined distance (e.g., the width of the pasture) of 

the device. The RAG box has been recently redesigned and 

now includes a text alert system to alert the rancher or 

herder via cell phone when the device is triggered by a 

radio-collared wolf. However, use of these devices require 

recapturing the wolf to replace the collar’s battery. 

Alternatively, the MAG device is activated by a passive 

infrared motion detector eliminating the need for collaring 

wolves. RAG and MAG boxes are generally available from 

USDA Wildlife Services offices with assistance from WS 

personnel. Defenders of Wildlife is making the redesigned 

RAG box available to state wildlife agencies.

Another tool used to frighten wolves from an area is LessThan-Lethal-Munitions (Figure 9) which fire nonlethal 

munitions (e.g., small plastic projectile, small bean bag, 

cracker shells) from a shotgun. This tool has a limited 

range and requires the shooter to be within 300 feet 

(100 m) of the wolf in order for it to be effective.

Guarding Animals

The use of guarding animals, such as dogs and donkeys, to 

protect flocks and herds from predators is a common 

nonlethal predation damage management tool.

Livestock Protection Dogs

Livestock protection dogs (LPD) are used to deter 

predators from livestock in many countries worldwide. 

Approximately 32% of surveyed livestock producers in 

several western states use LPDs to protect their flocks. In 

Colorado, a study reported sheep producers estimated 

their LPDs saved them an average of $3,216 annually from 

coyote depredations and reduced their need for other 

control techniques. 

Dog breeds most commonly used as LPDs include Great 

Pyrenees, Komondor, Akbash, Anatolian, and Maremma. 

However, these breeds may be vulnerable to wolf 

predation. With the expansion of wolf populations into the 

northern Rocky Mountains and the northwestern U.S., new 

larger-bodied breeds of LPDs from Europe have been 

evaluated for use as LPDs. A USDA Wildlife Services study 

examined three LPD breeds from Europe (Turkish Kangal 

(Figure 10), Bulgarian Karakachan, and the Portuguese 

Transmontano) and determined they all successfully 

protected sheep from a variety of large predators but 

showed different guarding traits and behaviors. Producers 

may want to balance the traits of multiple dog breeds by 

having some that prefer to stand guard with the flock and 

others that seek out and investigate potential threats.

Figure 9. Less-Than-Lethal-Munitions are fired from a shotgun at a wolf to scare the 

animal from an area.

Figure 10. The Turkish Kangal (shown) is one of three large European dog breeds

investigated to reduce predation by large carnivores.
Studies investigating the efficacy of LPDs have shown the 

dogs to be effective in some situations and ineffective in 

others. This may be due to the inherent difficulty of guard 

dogs protecting large flocks dispersed over rough terrain 

and in areas where thick cover conceals approaching 

predators. Some poorly trained or minimally supervised 

guard dogs have killed sheep and lambs, harassed or 

killed wildlife, and threatened people that intrude upon 

their territory. However, not all LPD failures or undesired 

behaviors stem from poor training or supervision. There is 

considerable behavioral diversity within a litter of guard 

dog pups; some turn into valuable and effective guard 

animals, while others do not, despite similar training and 

effort. The use of LPDs may preclude the use of other 

management methods, such as snares and traps. 

Donkeys and Llamas

Approximately 6% and 22% of surveyed livestock 

producers in the western U.S. use donkeys and llamas as 

guard animals, respectively. 

The protective behavior of donkeys apparently stems from 

their dislike of dogs. A donkey will bray, bare its teeth, 

chase and try to kick and bite wolves. If using guard 

donkeys, it is recommended to only use a jenny (female) or 

gelded jack (male; intact jacks are too aggressive towards 

livestock), and to place one donkey per flock or group and 

keep other donkeys or horses away to prevent the guard 

donkey from bonding with them versus the flock or herd. 

Furthermore, donkeys should be introduced to the 

livestock about 4 to 6 weeks prior to the onset of 

anticipated predation events to properly bond with the 

group. Donkeys are most effective in small, fenced 

pastures. Donkeys are relatively low maintenance. They 

generally eat pasture or rations suitable for other livestock 

and need only general health care – usually having their 

hooves trimmed once a year. 

Llamas are also a practical and effective tool for deterring 

predators, mainly coyotes, from livestock. Llamas can be 

kept in fenced pastures with sheep or goats, do not require 

any special feeding program, are relatively easy to handle, 

and live longer than LPDs. Traits that may be useful in 

selecting a guard llama include leadership (frequency with 

which individuals were followed by other llamas), alertness, 

and body weight. 

Although guard animals may not deter wolves completely, 

they may change the predators’ behavior and activity 

patterns when near livestock. In several states, such as 

Minnesota, both guard donkeys and llamas have been 

killed by wolves.

Repellents

There are no effective chemical repellents for use with 

wolves.

Shooting

Shooting is a selective and common method for lethally 

removing wolves. Safety is a critical factor and may preclude 

the use of firearms due to local laws or human habitation. 

Consider all available management options and proceed 

accordingly. 

The choice of firearm, caliber, and bullet will vary based on 

circumstances in the field. Rifles suitable for taking wolves 

include a .243 caliber, 6 mm, or larger with a suitable 

bullet type for taking an animal up to 120 lbs (55 kg).

Aerial Operations 

The use of aircraft for shooting wolves is regulated by 

the Airborne Hunting Act and is allowed under special 

permit in states where legal. Aerial operations are very 

selective, allowing for the removal of targeted packs or 

individuals.

Aerial operations, using fixed–winged airplanes and 

helicopters, are used for removing wolves that are 

depredating livestock. Fixed-wing aerial operations are 

limited primarily to open areas with little vegetative cover. 

Because of their maneuverability, helicopters are useful for 

shooting in areas of brush, scattered timber, and rugged 

terrain.

U.S. Department of Agriculture Page 11
Page 12 WDM Technical Series─Gray Wolves

Although aerial operations can be conducted over bare 

ground, they are most effective where there is snow cover. 

Wolves are more visible against a background of snow 

versus brown vegetation. Their tracks are also more visible 

in the snow. During the summer, vegetation that is still 

green also makes for a good background for spotting 

wolves.

Aerial operations can be more efficient if a ground crew 

works with the aircraft. Before the aircraft arrives, the 

ground crew often works to locate wolves in the area by 

eliciting howls. Two-way radio communication allows the 

ground crew to direct the aircraft toward the sound of the 

wolves, thus reducing search times.

In areas where aerial operations are allowed, federal law 

requires each state to issue permits. Some states or 

federal agencies may also require low-level flying waivers. 

Aerial operations require special skills and training for both 

the pilot and gunner.

The addition of radio-collars to study and locate the pack 

has also proved useful in wolf management for many 

western states. The radio-collar allows for identification of 

nearby packs that may be depredating livestock, and can 

then be relocated when needed.

Recreational Hunting

Where legal, firearms can be used to lethally take wolves 

causing damage found near depredation sites and 

livestock production areas. In some areas, local wolf 

populations also may be reduced through recreational 

hunting. Wolves may be called into firearm range with a 

predator call or by voice howling. 

Toxicants 

There are no toxicants currently registered for use with 

wolves in the United States.

Translocation

Although translocation efforts are expensive, they are often 

considered essential when dealing with rare or endangered 

predators. Translocation of wolves from Canada to central 

Idaho and Yellowstone National Park led to the recovery of 

wolves in the northern Rocky Mountains. However, 

capturing and moving animals causing damage is not 

considered a viable solution for solving wildlife damage 

problems. Wolves that have killed domestic animals and 

are translocated to prevent future damage typically leave 

the release site, travel great distances, and return to the 

original capture site or another area containing domestic 

animals where they resume depredation activities. 

Trapping

Trapping describes several types of tools and techniques 

used to commonly capture wolves. These include foothold 

traps and cable restraint devices that are designed to livecapture wolves. 

Trapping rules and regulations vary by state. Most states 

have regulations on various types of traps, baits, sets, and 

trap visitation schedules. Some states do not allow the use 

of foothold traps. Consult local laws and regulations prior 

to using any traps.

Wolf trapping success varies with local wolf densities 

and activity patterns, soil and snow conditions, trapper 

skill, abundance of livestock, wild ungulate density, 

other large carnivore activity, and other factors. 

Productive areas for capturing wolves are identified by 

observing wolf sign (e.g., wolf tracks, scat, scratches) 

and other evidence of regular wolf use. Often wolf sign is 

found on wolf travel routes such as forest roads, 

minimum maintenance roads, agricultural field roads, 

cattle trails, snowmobile trails, dikes and other routes 

through wolf habitat that provide easier travel for wolves 

than surrounding habitat. Setting traps on these wolf 

travel routes, as well as near wolf kills, rendezvous sites, 

and scavenging sites are effective ways to capture 

wolves.

Using a trap to selectively remove an animal that is 

causing depredation is difficult. However, removing wolves 

in close proximity to a damage site in the days immediately 

following a verified wolf depredation has proven successful 

in reducing or delaying subsequent damage. Generally, the 
more wolves removed, the longer the delay until the next 

damage incident. Sometimes just attempting to trap the 

offending animal and increasing the level of human activity 

in the area may deter future depredations.

Foothold Traps

Commonly used foothold traps for capturing wolves 

include #4, #5, #7, MB-750, Alaskan #9, Braun wolf trap, 

and others with coil-spring or double-long spring 

mechanisms. Wide, offset jaws, padded or rubber coated 

jaws (McBride EZ-grip), multiple swivels, and shock springs 

are common modifications on foothold traps to help 

reduce capture-related injuries.

Foothold traps for wolves can be equipped with a long 

(minimum 8 ft [2.4 m]) chain attached to a heavy duty twopronged drag in areas with suitable vegetation (Figure 11). 

A drag allows a captured wolf to move from the set 

location and seek shelter in vegetation. Drags are typically 

used instead of in-ground anchors in sandy or loose soils, 

and in areas with dense vegetation for the drag to hook 

onto away from the trap site.

In terrain or habitat unsuitable for drags, foothold traps 

can be anchored solidly at the trap set location with the 

use of trap stakes (Figure 12) or other anchoring systems. 

Often two re-bar stakes (1⁄2-inch (1.3 cm) diameter by 24-

inch (60 cm) long) are hammered into the ground in a 

“cross-staked” pattern to prevent stakes from being pulled 

out by a captured animal. Alternatively, a “bullet” or earth 

anchor can be used to secure a foothold trap (Figure 13). 

These devices are attached to the trap chain using a chain 

or strong cable (1/8-inch [0.3 cm] diameter minimum), 

and driven into the ground to a depth of 18 to 24 inches 

(46 to 61 cm) below the trap with a specialized driver.

All swivels, j-hooks, s-hooks, and other connections on 

wolf traps and chains should be spot-welded so captured 

wolves cannot open the connections and escape. Pantension devices also should be considered to minimize 

captures of smaller nontarget species. Use of trap 

monitors can be beneficial for traps set in areas with 

difficult access, or in areas occupied by endangered 

species requiring prompt removal of an animal from the 

U.S. Department of Agriculture Page 13

Figure 12. Foothold trap configured with two stakes for anchoring the trap in place.

Figure 11. Foothold trap configured with chain and 2-pronged drag-hook.

Figure 13. Foothold trap equipped with a “bullet” anchor which is driven into the 

ground. When the chain is pulled, the anchor pivots, anchoring the trap in place.
Page 14 WDM Technical Series─Gray Wolves

trap. Additional anchoring of the trap may be needed 

when working in areas with grizzly bears to allow 

release of the bear from the trap. 

A foothold trap usually is set in the ground by digging a 

trench just deep and wide enough to fit the trap, stake (or 

drag), and chain in the bottom of the hole. The trap is set 

firmly on top of the buried chain and should be about 1⁄4 to 

1⁄2-inch (5 to 10 mm) below the soil surface (Figure 14). A 

piece of canvas, cloth, mesh screen, waxed paper, or a 

plastic sandwich bag is placed over the trap pan to prevent 

soil from getting beneath the pan and preventing it from 

being depressed by the target animal. Alternatively, closed 

cell foam or other compressible material can be placed 

underneath the trap pan to keep out dirt. The weight of a 

wolf’s foot on the pan will compress the material under the 

pan and allow the trap to trigger. Cover the trap with soil 

and other natural materials (i.e., leaves, pine needles, dry 

grass) found in the area near the trap.

There are two main types of foothold trap sets: blind and 

flat. A blind or trail set is used to trap an unsuspecting wolf 

Figure 14. Placement of a foothold trap in the ground begins with two-stakes in a “cross-staking” configuration and chain to anchor the trap in place (A), then dirt is filled around 

the trap with a plastic baggie over the pan preventing dirt from getting under the pan (B), more dirt is then sifted over the trap (C), with the final trap set being blended into the 

surroundings to conceal the trap (D). 

A B 

C D 
as it is traveling on its commonly used trails. It is set 

without a bait or attractant. A flat set takes advantage of a 

wolf’s curiosity and urge to investigate smells. It is often 

set off of the travel route and baited with an attractant, 

such as meat bait, scat or urine, on or near a grass clump, 

log end, rock, bone or some other natural backing to entice 

the wolf to stop and smell the attractant, but not roll on it.

Alternatively, the attractant could be placed in a small hole 

(at least 6 inches [15-cm] deep) dug behind the trap.

Many states do not allow trapping of wolves, or restrict 

trapping near a carcass or exposed bait, so check local 

and state regulations. Foothold traps must be checked 

often to minimize the amount of time animals are 

restrained. To avoid catching nontarget animals, such as 

bears, eagles and vultures, do not place foothold traps 

near a carcass.

Cable Restraint Devices

Cable restraint devices (also known as snares) are made 

of varying lengths and sizes of wire or cable that is looped 

through a locking device that allows loop to tighten 

(Figure 15). There are generally two types of cable 

devices: neck and foot. Neck cable devices can be used 

to restrain a live animal or as a lethal tool depending on 

their design, lock type, cable diameter, anchor type, 

length, and whether the captured wolf can entangle itself 

in nearby vegetation or fencing. The device is set where 

an animal crawls under a fence, travels through tall 

grass, brush or some other narrow passageway. The 

device is placed so the animal must put its head through 

the cable loop as it passes through the restricted area. 

The device’s loop tightens as the wolf proceeds through 

the loop and the lock travels toward the terminal end of 

the cable, holding the captured wolf by the neck. Cable 

devices should be strong enough to resist twisting and 

chewing by a captured wolf. Cable that is 1/8-inch (0.3 

cm) diameter (e.g., 7 x 7 cable) is frequently used. A 

cable device’s loop is typically 13 to 16 inches (33 to 41 

cm) in diameter and is placed so it hangs 16 to 18 inches 

41 to 46 cm) above the ground. 

Care should be taken when using neck cable devices to 

avoid unintentional capture of wild ungulates, livestock, 

or bears. Selectivity, effectiveness, and risk of capture 

of nontarget species can be improved with proper 

design and placement. A breakaway device and a snare 

stop incorporated into the cable device’s lock allow 

larger animals to escape if accidentally caught and 

should be considered in areas where there is the 

potential to catch nontarget species. Diverter wires or 

sticks placed directly over the set are used successfully 

in some locales to reduce unintentional capture of wild 

ungulates. Deer and livestock can be prevented from 

interfering with a cable device by placing a pole or 

branch across the trail, directly over the set about 3 ft 

(0.9 m) above the ground.

Spring-activated cable devices are used to capture 

wolves and other large predators by the foot. When the 

animal steps on the trigger the spring is released, 

propelling the device’s loop around the foot. The animal 

instinctively recoils, tightening the cable.

Foot cable devices can be used in a cubby set (a set which 

funnels the wolf to step on the trap from one direction), or 

set in a narrow trail known to be traveled by wolves. 

Selectivity of the cable device may be improved by placing 

sticks under the trigger that break only under the weight of 

U.S. Department of Agriculture Page 15

Figure 15. Cable restraint devices are made of varying lengths and sizes of wire or 

cable looped through a locking device that allows the loop to tighten.
Page 16 WDM Technical Series─Gray Wolves

heavier animals. Open-cell foam pads can be placed under 

trigger pans to prevent unintentional triggering of devices 

by small mammals. Foot cable devices are generally not as 

effective at capturing wolves as more traditional foothold 

traps, but they are lighter and easier to carry.

Handling and Euthanasia

Wear protective equipment (i.e., disposable latex or nitrile 

gloves, safety glasses) when handling live or dead wolves. 

Avoid contact with claws, teeth, blood, saliva, urine, or 

feces.

The most dangerous part of a wolf is its mouth with sharp 

teeth and the ability to break bones with the power of its 

bite. A catchpole or Y-pole may be used to momentarily 

restrain a wolf, but administration of immobilizing drugs is 

recommended if handling or transporting the animal is 

required.

When working with a live wolf, move slowly and 

deliberately. Speak in a calm voice. Place a hood or towel 

over the wolf’s eyes to reduce stress. Keep a live wolf 

cool or in a shaded area to avoid heat-related injury.

Thoroughly washing your hands, body, and clothing 

after trapping and handling wolves will reduce the 

chances of contracting a zoonotic disease or parasite, 

such as tapeworms.

The American Veterinary Medical Association provides 

guidelines for euthanizing animals. Pharmaceutical 

euthanasia agents (including barbiturates) can only be 

administered by a licensed veterinarian or someone 

working under the direction and control of a veterinarian. 

It is recommended that applicators use a sedative 

followed by an intravenous injection of the euthanasia 

agent.

Captured wolves may also be euthanized with a well-placed 

shot to the brain with a hollow-point bullet from a .22 

rimfire cartridge (or of equivalent or greater velocity and 

muzzle energy) or a centerfire rifle bullet to the heart, if the 

brain cannot be safely and reliably targeted. 

Disposal

Check your local and state regulations regarding carcass 

disposal. In some disease-related cases, deep burial, or 

incineration may be warranted. 

Economics

Economic benefits of wolves are mainly through 

consumptive and non-consumptive uses. Wolf hunting 

is now allowed in much of the northern Rocky 

Mountains, which generates revenues that would be 

considered consumptive use (e.g., the sale of licenses 

for hunting and trapping wolves in Montana is over 

$400,000 per year). Plus, hunters spend money for 

travel, housing, food, and equipment, generating 

income for hotels, restaurants, and hunting 

guides. Some ranchers may be able to offset losses 

associated with wolves by providing access to their 

property and services (e.g., guiding, housing) to people 

that hunt wolves. An outfitter in Idaho offers wolf 

hunting on Idaho ranches for $3,800 for a single 

hunter.

In terms of non-consumptive use, wolves provide 

opportunities for people to view, film, photograph, 

listen to, or otherwise experience wolves in their 

natural habitats. Tourists flock to Yellowstone National 

Park for a chance to see wolves. When first introduced 

into Yellowstone National Park in 1995, economists 

estimated that visitor use would increase by 5% for 

out-of-area residents and 10% for local residents. Ten 

years later, economists confirmed that visitation 

increased as predicted and that wolf-related visitation 

produced $47 million annually in travel expenditures in 

Idaho, Montana, and Wyoming.

The largest economic cost is from wolves harassing 

and/or killing livestock (Figure 16). The economic cost 

of livestock killed by wolves is determined by 

multiplying the number of animals lost times fair 

market value. However, counting these losses is 
difficult because the exact number of livestock killed 

by wolves is not known. From 1987 to 2005 in 

Montana, Idaho, and Wyoming, 528 cattle, 1,318 

sheep, 83 dogs, 12 goats, 9 llamas, and 6 horses were 

confirmed killed by wolves, and over $550,000 was 

paid from a private compensation fund (Defenders of 

Wildlife). In 2014, the U.S. Fish and Wildlife Service 

confirmed a total of 136 cattle (both adults and calves) 

and 114 sheep (adults and lambs) killed by wolves in 

2014 in the northern Rocky Mountains. Generally, the 

proportion of livestock killed by wolves is low, and 

mortality caused by wolves is a small economic cost to 

the livestock industry as a whole. Although wolf 

predation on cattle and sheep accounts for less than 

1% of the annual gross income from livestock 

operations in the northern Rocky Mountains, these 

costs are unevenly distributed and localized.

In the Great Lakes region, the 3 states (Wisconsin, 

Michigan, Minnesota) reported a total of close to 

$300,000 in compensation for wolf damage to 

livestock in 2019. In 2020, these 3 states also 

reported about $770,000 in management costs 

dealing with wolf damage (this includes federal and 

cooperator funding, and funds for employing nonlethal 

methods). 

Additionally, studies show that costs could be higher 

when including unconfirmed deaths and indirect losses 

such as lower market weights, reduced conception 

rates due to stress, and producer mitigation costs to 

deter wolves or to seek compensation. For example, 

one study found that calves in herds that experienced 

predation were 22 lbs lighter and, when added across 

all calves in those herds, accounted for a greater loss 

than confirmed depredations. Other studies found 

unverified and indirect losses to be at least 6 times 

that of verified losses. A later study found that these 

estimates of unaccounted losses may be 

overstated. Clearly, more research is required to know 

exactly how much producers might lose if wolf 

populations expand.

Another potential cost of wolves is reduced income for 

some businesses, primarily big game hunting. At a 

local level in states with high wolf populations, elk 

numbers are stable or increasing in many areas where 

wolves and elk interact, but they have declined in 

others. At the statewide level, the number of elk 

harvested by hunters has not declined in the northern 

Rocky Mountains, despite increases of wolves. An 

economic analysis in Montana concluded that, overall, 

wolves have not had a significant economic effect on 

elk harvest in the state. Rather, demand for hunting 

shifted from the southwest region near Yellowstone to 

areas farther away from where wolves were first 

introduced. However, at a local level, where wolves 

contribute to declines in big game herds and hence 

hunting opportunities, this resulted in a cost to those 

reliant on hunting to support their livelihoods.

Many states fund compensation programs for livestock 

producers impacted by confirmed wolf depredations with 

some non-governmental organizations contributing 

toward nonlethal damage management programs (e.g., 

funding range riders and fladry) on private and public 

lands.

Livestock compensation programs for losses due to wolf 

damage vary by state with some states compensating 

only for verified losses, and others compensating for 

both verified losses and unrecovered livestock. A study 

in Idaho documented that for every verified wolf

U.S. Department of Agriculture Page 17

Figure 16. Direct damage costs from wolves include the death and caring of injured 

livestock as a result of being pursued or attacked.
Page 18 WDM Technical Series─Gray Wolves

depredation, there may be 7 to 8 head of cattle that 

were also depredated but never found or verified. Some 

states, therefore, make compensation payments at a 

ratio of 7 head for every one verified loss. Check state 

regulations for information on compensation payment 

programs.

Current compensation programs generally only consider 

direct losses from wolf predation, while indirect effects 

may be just as costly. The presence of wolves in an area 

may cause livestock to change their behavior, similar to 

changes in elk behavior following wolf reintroductions. 

Increased vigilance in livestock and less time foraging 

may cause livestock to lose weight, thereby reducing 

overall herd productivity which translates into reduced 

profit margins when selling. Other indirect effects 

include changes in weaning weights and conception 

rates, and increased cattle sickness. Producers have 

reported less weight gain in cattle and underutilized 

forage in pastures having high levels of wolf activity. The 

presence of wolves in an area may result in increased 

costs associated with livestock management, such as 

spending more time patrolling herds to keep wolves’ 

away, locating kills, and potentially implementing 

increased nonlethal measures that were not necessary 

before. 

Wolf damage estimates to livestock varies by state. For 

example, Minnesota has a well-established wolf 

population and control of wolves for livestock 

depredations has been quite consistent for several 

decades. Conversely, in neighboring Wisconsin, the wolf 

population has grown steadily since the late 1990s 

(Figure 17) with increasing depredations on livestock. The 

re-establishment of wolves grew rapidly following 

reintroduction and current populations in Montana, 

Wyoming, and Idaho are relatively constant with surplus 

animals dispersing into Oregon, Washington, California, 

Utah, and Colorado. Each state has or is developing wolf 

management plans for addressing their wolf populations 

based on the wolves’ status (i.e., endangered, delisted, 

etc.), population size, and public attitudes.

Figure 17. Wolf population numbers in Wisconsin, 1980-2018.
Most state and federal agencies recognize the need to 

manage wolf populations, particularly addressing

livestock depredations. Educating the public on these 

needs and balancing the public attitudes towards lethal 

removal of wolves makes the situation controversial. 

The economics gained by some, at the expense of 

others, will continue to be debated as wolf populations 

expand into surrounding states.

Species Overview

Identification

The gray wolf belongs to the Canidae family in the genus 

Canis. With the help of advanced genetic analysis, there 

are currently four recognized subspecies of gray wolf in 

North America. These include:

• Arctic wolf (Canis lupus arctos) - endemic to 

the Elizabeth Islands, Canada

• Great Plains wolf (Canis lupus nubilus)

• Mexican wolf (Canis lupus baileyi)

• Northwestern wolf (Canis lupus occidentalis)

The red wolf (Canis rufus) is recognized as a separate 

species. Historically, the red wolf was found throughout the 

eastern United States from east Texas to Florida and as far 

north as Pennsylvania. Today, a small wild population 

resides in eastern North Carolina. Approximately 200 

individuals are found in zoos and other captive facilities 

across the United States.

Physical Description

Canis lupus is the largest living canid. Males weigh from 44 

to 175 lbs (20 to 80 kg) and females 35 to 120 lbs (16 to 

55 kg), with larger individuals found further north. Although 

called the gray wolf, their pelage varies with some wolves 

having fur that is completely black, to the Arctic wolf which 

has fur that is completely white. In general, the pelage of 

gray wolves is tan or light brown mixed with brown, black, 

and white.

Range

Historically, the gray wolf was found throughout Eurasia 

and North America except in the southeastern United 

States. Gray wolves can live in almost all types of habitats 

from tundra to forests and from deserts to swamps. 

Present distributions have been severely restricted and 

gray wolves are found primarily in Alaska, Canada, 

northern Minnesota, northern Wisconsin, Michigan’s 

Upper Peninsula, and areas of Idaho, Wyoming, 

Washington, Oregon, Arizona, New Mexico, and Montana 

(Figure 18). However, wolves are currently expanding their 

range in the contiguous United States. Between 1995 and 

1996, 31 gray wolves were reintroduced to Yellowstone 

National Park. In 2019, there was an estimated 60 wolves 

in the Park, but over 520 estimated in the Greater 

Yellowstone Ecosystem. Wolf packs have recently been 

found in northern California and northwestern Colorado.

U.S. Department of Agriculture Page 19

Figure 18. Range of wolves in North America as of 2018. Tan color indicates range of 

the gray wolf, while green color indicates range of the Mexican wolf in the southwest 

U.S. The range of the red wolf in northeastern North Carolina is not depicted.
10 weeks old and begin to learn about the social 

structure of the pack and hunting. When the young are 

approximately 10 to 20 weeks old, the pack leaves the 

den area and moves to a “rendezvous site” where there 

are numerous “nest” sites, trails and play areas. The 

rendezvous site (or sites) serves as a focal point for 

pack members to congregate and are often used 

through the summer months into early fall. When the 

young-of-the-year are large enough to travel with the 

adult wolves, the rendezvous sites are generally 

abandoned.

Mortality and Life Span

Wolves in the wild typically live 4 to 5 years, but there are 

reports of wild 11-year-old female wolves producing litters; 

although older female wolves may enter reproductive 

senescence before that age. 

Wolves primarily die from accidents, disease, starvation, 

injuries from fights with other wolves, injuries from prey, 

and human-caused mortality. As densities of prey 

decrease, more wolves die due to starvation. Humancaused mortality is due to legal and illegal hunting and 

vehicle accidents. 

The effects of pathogens and parasites on wolf populations 

is not well documented. In some wolf populations, 2 to 

21% of wolf mortality was attributed to disease. The most 

common diseases of adult wolves are mange and rabies, 

with pups being susceptible to canine distemper virus and 

canine parvovirus. The transmission of diseases, such as 

canine parvovirus, from domestic dogs to wild wolves is a 

conservation concern. A study of serum samples from 387 

wolves in Minnesota documented serologic exposure to 

eight diseases. Diseases included canine parvovirus (82% 

adults, 24% young), canine adenovirus (88% adults, 45% 

young), canine distemper virus (19% adults, 5% young), 

eastern equine encephalitis (3% adults), West Nile virus 

(37% adults, 18% young), heartworm (7% adults, 3% 

young), and Lyme’s disease (76% adults. 39% young). 

Parasites were found in 15% of fecal samples examined. 

Mange and lice are also present in many wolf populations. 

There is no reported relationship between prey density and 

the incidence of disease in wolf packs.

Page 20 WDM Technical Series─Gray Wolves

Pack Structure and Function

Wolves are social animals that live in family-based groups 

or “packs” that have a linear-hierarchical social structure. 

The “alpha” male and female are the dominant individuals 

in a pack. All other wolves in the pack are subordinate. An 

individual wolf’s social status within a pack can change 

over time and is determined by age, health, physical 

condition, and other factors.

Packs function as a unit that defends a specific area called 

a territory. While defense of the territory is mainly 

conducted by the alpha pair, all individuals undertake 

subtle defensive actions including scent marking and 

howling. Scent marking occurs mostly along territorial 

boundaries. Howling is used not only to communicate 

among pack members but also to inform neighboring 

packs of the resident packs’ presence. The alpha pair are 

generally the only individuals to engage in direct attacks on 

encroaching wolves.

Reproduction

In general, the alpha pair breeds in January or February. 

Subordinate females occasionally breed and produce a 

successful litter.

After a gestation period of 62 to 63 days, a pregnant 

female wolf gives birth to an average of 6 young. Litter 

sizes range from 1 to 11 individuals. The young are born 

blind and are completely dependent on the mother during 

lactation, and on the pack for food provisioning once the 

young are weaned. Members of the pack feed the young 

by regurgitating food or indirectly by provisioning the 

lactating female. Young reach sexual maturity around 3 

years old at which time they may disperse and leave the 

pack.

Dens and Rendezvous Sites

Pregnant female wolves give birth to young in a den 

where they remain for approximately 5 weeks. Although 

the young are mobile enough to move around, they stay 

relatively close to the den until they are approximately 
Population Status

As of 2019, stable wolf populations exist in many regions 

in the U.S., including Alaska, Minnesota, Wisconsin, 

Michigan, Wyoming, Montana, and Idaho, with growing 

populations in parts of Oregon and Washington (Figures 

19, 20). Wolves have recently been documented in 

northern California and northwestern Colorado. A small

population of introduced Mexican wolves exists in Arizona

and New Mexico, and a small population of red wolves

exists in eastern North Carolina. Both the Mexican and red 

wolf populations are considered more vulnerable to

extinction than other North American wolf populations.

Food Habits

As obligate carnivores, wolves eat primarily meat. Their

main prey includes large ungulates, such as moose, 

deer, and elk. In Alaska, wolves also prey upon caribou 

and musk oxen. Beavers are an important seasonal food 

source in some locales. Occasionally, wolves eat small 

mammals or scavenge on carcasses. While wolves are 

more successful hunting vulnerable prey (i.e., small, 

young, or old individuals that are easy to catch), they are 

opportunistic hunters, pursuing prey whenever the 

chance arises. However, successful capture of prey is 

often very low.

Voice and Sounds

Gray wolves make a variety of sounds, including barks, 

growls, howls, whimpers, whines, and yelps. Whines, 

whimpers and yelps indicate submissiveness, distress or 

friendly behaviors, while growls and barks suggest 

dominance or aggression. While most vocalizations are 

used to communicate over short distances, howls can

carry over long distances and are used to communicate 

between packs or to members within a pack who are 

separated from each other. Although the specific purpose 

of howls is not clear, it is thought that howling aids in the 

coordination of movements among pack members, and 

facilitates spacing among packs, social bonding among 

pack members, and mating.

U.S. Department of Agriculture Page 21

Figure 19. Minimum number of wolves and number of depredation events in Oregon, 

2009-2018. 

Figure 20. Known number of wolves and number of breeding pairs in Washington, 

2008-2018. 
Legal Status 

The legal status of wolves varies from state to state. 

For example, in California the gray wolf is protected as 

an endangered species under both the California and 

federal Endangered Species Acts. In Wyoming, gray 

wolves are delisted and managed by the state. In North 

Carolina, the red wolf is protected as a federally listed 

endangered species.

The legal status of many wolf populations remains in 

flux as opposition to delisting in some states is 

challenged in the courts. Check the legal status of 

wolves in the state prior to implementing any 

management methods.

Page 22 WDM Technical Series─Gray Wolves

Figure 21. Track sizes of a wolf, domestic dog, and coyote. 

Tracks and Sign

Although adult wolves, adult coyotes, and large dogs have 

four symmetrical toes on the front and hind feet, adult gray 

wolf tracks are much larger and distinguishable by their 

more oval shape and forward pointing middle toes (Figure 

21). Other wolf signs include scat, urine deposits, and 

scratch-ups (scratches on the ground), which are generally 

thought to be territorial boundary markers. Wolf kills are 

characterized by massive trauma and large tooth marks 

usually on the hindquarters or flanks.
U.S. Department of Agriculture Page 23

Keywords

Canids, Canis lupus, Depredation, Fladry, Guardian 

animals, Livestock, Snares, Traps, Wolves

Citation

Gese, E.M., J.P. Hart, and P.A. Terletzy. 2021. Gray Wolves. 

Wildlife Damage Management Technical Series. USDA, 

APHIS, WS National Wildlife Research Center. Fort Collins, 

Colorado. 29p.

Disclaimer

Wildlife can threaten the health and safety of you and 

others in the area. Use of damage prevention and control 

methods also may pose risks to humans, pets, livestock, 

other non-target animals, and the environment. Be aware 

of the risks and take steps to reduce or eliminate those 

risks. 

Some methods mentioned in this document may not be 

legal, permitted, or appropriate in your area. Read and 

follow all pesticide label recommendations and local 

requirements. Check with personnel from your state 

wildlife agency and local officials to determine if methods 

are acceptable and allowed. 

Mention of any products, trademarks, or brand names 

does not constitute endorsement, nor does omission 

constitute criticism. 

Acknowledgements

Figure 1. Photo by Eric Gese, USDA-APHIS Wildlife Services

Figure 2. Graph from Montana Fish, Wildlife, and Parks

Figure 3. Graph from Minnesota Department of Natural Resources

Figure 4, 11-13, 15. Photos by John Hart, USDA-APHIS Wildlife Services 

Figure 5-9, 14. Photos by USDA-APHIS Wildlife Services 

Figure 10. Photo by Julie Young, USDA-APHIS Wildlife Services 

Figure 16. Photo by Len Fortunato Courtesy Heather Thomas 

Figure 17. Graph from Wisconsin Department of Natural Resources

Figure 18. Graph from 2018 IUCN Red List, Canis lupus

Figure 19. Graph from Oregon Department of Fish and Wildlife

Figure 20. Graph from Washington Department of Fish and Wildlife

Figure 21. Drawing by David Moskowitz; http://westernwildlife.org/gray-wolf-outreach-project/signs-of-wolves/

We thank Julie Young, Anthony Duffiney, John Steuber, and Michael Burrell for providing critical reviews of this manuscript.

Glossary

Alpha: The highest ranking individual in a social group. 

Other animals in the same social group may exhibit 

deference or other species-specific subordinate behavior 

towards the alpha or alphas. 

Carnivore: Animal whose diet mainly consists of meat.

Depredation: The act of consuming agricultural resources 

(i.e., crops or livestock). 

Fladry: A simple, nonlethal tool used to prevent livestock 

predation. It is a temporary fence, consisting of a line of 

brightly colored flags hung at regular intervals along the 

perimeter of a pasture. 

Nontarget Species: Animals inadvertently or unintentionally 

impacted by a management action. 

Territory: The area a wolf pack resides in and actively 

defends from other intruding wolves. 

Ungulate: A hooved, plant-eating mammal, such as an elk, 

moose, sheep, cow or horse. 
Page 24

Resources

Acorn, R.C. and M.J. Dorrance. 1998. Coyote predation on livestock. AGDEX 684–19, Alberta Agriculture, Food, and Rural 

Development, Edmonton, Canada.

Andelt, W.F. 1992. Effectiveness of livestock guarding dogs for reducing predation on domestic sheep. Wildlife Society 

Bulletin 20:55–62.

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Appendix 

 

 

Type of Control 

 

Available Management Options 

Animal Husbandry • Carcass removal and disposal

• Herders/shepherds/”Range Riders”

• Night penning and shed lambing

• Pasture selection

• Synchronized birthing 

Exclusion • Woven-wire and electric fencing

• Corrals

• Fladry/Turbo-fladry

Fertility Control No fertility control agents available

Frightening Devices • Less-Than-Lethal Munitions

• Radio Activated Guard and Motion Activated Guard

• Strobe lights and noise makers

Guarding Animals Livestock protection dogs, donkeys, llamas, and other guarding animals

Repellents No effective chemical repellents available

Shooting May require use of non-toxic/non-lead ammunition; Allowed with proper Federal and State permits 

Trapping Foothold traps, cable restraint devices; Allowed with proper Federal and State permits

Damage Management Methods for Gray Wolves