Natural History

San Mateo AM1157 in the summer of 2011.
(Photo Courtesy of the Mexican Wolf Interagency Field Team)

The Mexican gray wolf (Canis lupus baileyi), also called the Mexican wolf, or "lobo," is the smallest, southern-most occurring, rarest, and most genetically distinct subspecies of gray wolf in North America. 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 lobo 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 wolves in the United States. Wolves were trapped, shot, clubbed, and poisoned by private individuals and government agents. 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 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.

Like other wolves, 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.

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. 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. However, in areas where wolves and livestock coexist, such as Minnesota, Montana, and Alberta, Canada, wolves take an average of less than one-tenth of one percent (0.1%) of available livestock.

The mission of the U.S. Fish and Wildlife Service is working with
others to conserve, protect, and enhance fish, wildlife, plants and
their habitats for the continuing benefit of the American people.

All images Credit to and Courtesy of the U.S. Fish and Wildlife Service unless specified otherwise.