Mexican Wolf
Southwest Region Ecological Services
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Mexican wolf sleeps on a rock. Credit: USFWS. Mexican wolf sleeps on a rock. Credit: Heather Walters..
What is a Mexican Wolf?

General Description
The Mexican wolf (Canis lupus baileyi), is the smallest, southern-most occurring, rarest, and most genetically distinct subspecies of gray wolf in North America. Mexican wolves typically weigh 50 - 80 pounds and measure about 5 ½ feet from nose to tail, and stand 28 to 32 inches at the shoulder. They have a distinctive, richly colored coat of buff, gray, rust, and black, often with distinguishing facial patterns; solid black or white variations do not exist as with other North American gray wolves.

Historically, the core range of Mexican wolves occurred throughout mountainous regions from central Mexico, through southeastern Arizona, southern New Mexico, and southwestern Texas. More recent information obtained from examining historical wolf specimens however, suggests that Mexican wolves may have roamed farther north. The Mexican wolf was common throughout its core range through the mid-1800s. Towards the turn of the century, however, high cattle stocking rates and declining populations of native prey, such as deer and elk, caused many wolves to prey on livestock. This led to intensive efforts to eradicate Mexican wolves in the southwestern United States. By the mid-1900s, Mexican wolves had been effectively eliminated from the United States, and populations in Mexico were severely reduced. Following the passage of the Endangered Species Act in 1973, Mexican wolves were listed by the U.S. Fish and Wildlife Service as an endangered species in 1976, thereby prompting recovery efforts to save the species from extinction.

Mexican wolf experimental population
Mexican wolf Experimental Population Area Map. Download a copy. USFWS.

Pack Life
Mexican wolves have a complex social structure and an intricate communication system that includes scent marking, body postures, and numerous vocalizations such as howling, barking, whining, and growling. They live in extended family groups, or packs, consisting of an adult mated pair and their offspring, often from several generations. The alpha pair is usually monogamous, and they typically are the only breeding animals in the pack. Although highly variable, a typical Mexican wolf pack might consist of 4 - 8 animals, with a territory encompassing up to several hundred square miles. Generally, they breed in February and give birth in April or early May to four to six pups after a 63-day gestation period.

Wolf pack scavenges for food. Credit: USFWS.
Wolf pack scavenges for food. Credit: USFWS.

Mexican wolves hunt cooperatively to bring down prey animals usually much larger than themselves. This is accomplished primarily by chasing their prey often over large distances; however, hunting behavior and strategies likely vary depending on terrain and prey size and availability. Native prey for Mexican wolves includes elk, mule deer, white-tailed deer, javelina, rabbits, and other small mammals. Mexican wolves can and do occasionally kill livestock, particularly young animals. Mexican wolves also readily scavenge on carcasses of prey species.

Mexican wolves are found in a variety of southwestern habitats; however, they are not low desert dwellers as once commonly believed. They prefer mountain woodlands, probably because of the favorable combination of cover, water, and available prey.

2016 Mexican Wolf Experimental Population Area Summary

At the end of 2016, at least 113 Mexican wolves occupied the Mexican Wolf Experimental Population Area (MWEPA). This represents a 16.5% increase from the 2015 minimum population estimate of 97. Fourteen of the twenty-three packs documented in the MWEPA exhibited denning behavior and pups were observed in all fourteen packs. A minimum of 65 pups were documented during the year, with a minimum of 50 surviving in the wild at year's end. Eleven of these packs met the definition of breeding pair at the end of 2016. All packs at the end of 2016 were formed naturally in the wild.

Fourteen natural pairings of breeding age wolves in the MWEPA population occurred in 2016. The natural pairings of dispersing or single wolves resulted in the designation of two new packs, Baldy and Leopold. Six new pairs formed during 2016; however, only three remained by the end of December. In addition, breeding animals were naturally replaced in six other packs.

At the conclusion of the 2016 end-of-year count, 54 of the documented 113 wolves in the MWEPA, were equipped with radio collars (48% of the known population). Many of these wolves were fitted with GPS/ARGOS satellite telemetry collars. These radio collars use satellite technology to record accurate wolf locations on a frequent basis. This information can be used by biologists to gain timely information pertaining to many facets of wolf behavior such as dispersal, territory use, predation data, and denning behavior.

The IFT conducted three cross-foster events involving three packs, resulting in the initial release of six neonatal wolf pups. Two pups were introduced into each of the three dens. Each den initially contained five wild-born pups; the addition of two cross-fostered pups resulted in each of the dens having a total of seven pups after the operation. All of the cross-foster events were initially considered successful (pups from captivity were introduced into wild dens; the event did not result in the abandonment of the den), and some pups survived in each of the dens until the late fall and early winter. Two cross-fostered pups were confirmed alive at the end of 2016 and others may have survived in each of the cross-fostered packs.

A Luna pack wolf in the winter of 2011. Credit: Mexican Wolf Interagency Field Team.
A Luna pack wolf in the winter of 2011. Credit: Mexican Wolf Interagency Field Team.

The IFT documented 14 mortalities of free-ranging wolves in 2016, including 9 adults, 3 subadults, and 2 pups. This in an 8% increase from documented free-ranging wolf mortalities (13) in 2015.

Home ranges were calculated for 20 packs or individuals exhibiting territorial behavior. The 95% fixed kernel method produced an average home range size of 255 square miles, with home range size varying from 78 square miles to 858 square miles.

Native prey utilized by wolves consisted primarily of elk; however, there were also 50 confirmed fatal livestock depredations.

In 2016, the IFT analyzed 72 reports of wolf sightings from the public; 88% of these reports were non-wolf sightings (coyote, dogs, etc.), while 12% of these reports were determined to be Mexican wolves. The IFT searched 16 areas in the MWEPA for new wolf presence and 11 uncollared wolves in the MWEPA were documented. As a result of these efforts nine wolves where included in the annual population count.

Mexican wolf project personnel provided a total of 24 presentations and status reports to approximately 1,000 people in federal and state agencies, conservation groups, rural communities, schools, wildlife workshops, and various other public, private, tribal institutions throughout Arizona, New Mexico and White Mountain Apache Tribal lands. Ninety-two percent of the presentations were for the MWEPA target audience. In addition, biweekly contacts were made to cooperating agencies and stakeholders to inform stakeholders of wolf locations Mexican wolf reintroduction project updates were emailed to an average of 18,287 people a month.

Definitions Breeding pair: a pack that consists of an adult male and female and at least one pup of the year surviving through December 31. Cross-Foster: the removal of offspring from their biological parents and placement with surrogate parents. If the offspring were in captivity at the time of the removal this is also an Initial Release.



Additional Information Chart that identifies the difference between a mexican wolf and a coyote
Difference between Mexican wolf and coyote

Difference between Mexican wolf paw print and coyote paw print
Difference between Mexican wolf paw print and coyote paw print

Wolf pup howls in wild
Listen to Mexican wolves howling in the wild. Credit: © Doctor John and Mary Theberge from the University of Waterloo in Ontario, Canada

Read the transcript of the Howling wolves.

Last updated: June 19, 2018