A subspecies of the Gray wolf, the Mexican gray wolf is commonly known as "El lobo". It is gray with light brown colored fur on its back, and has long legs and a sleek body, which means it can run fast. Once there were thousands of these wolves but in the U.S. many had been killed by the mid-1970s, and just a handful existed in zoos. In 1998, the U.S. Fish and Wildlife Service, under Jamie Rappaport Clark (who became president of Defenders of Wildlife), introduced 11 Mexican gray wolves into the wild in Arizona. Their numbers have grown slowly and they are currently the world’s most endangered wolf subspecies. These animals can live in captivity for up to 15 years, but it is suggested that their life span is rather less in the wild, probably not more than 10 years.
Mexican gray wolves were once widespread from central Mexico through the southwestern U.S. They have now been reintroduced in southeastern Arizona in the Apache National Forest, and may move into western New Mexico to the adjacent Gila National Forest as the population grows. These wolves are also being reintroduced in Mexico. They prefer habitats of mountain forests, scrublands and grasslands.
Mexican gray wolves are a very social species, living in packs which have complex social structures, including the alpha male and female, the breeding pair, with their offspring. The others in the pack are “helpers”. The hierarchy of dominant and subordinate individuals enables the unit to work. Wolves usually travel with their pack and establish a territory that could be 30 square miles up to more than 500. They define their territory with scent markings and vocalizations such as barks, growls, and their legendary howl. Packs in regions such as the desert where typically prey is small may have 7 or fewer members, up to 30 or more where the prey is large.
Mexican wolves are monogamous, with only the pack’s alpha pair breeding each year. The season for mating is from mid-February to mid-March and gestation lasts about 63 days. Litters number 4 to 7 pups, which are born blind. They are reared inside a den which is a burrow or natural hole. Every member of the pack cares for the pups, feeding them regurgitated meat after hunts. They are weaned in about the fifth week, approaching adult size early in winter. By autumn, when the pups are able to travel with the adults, a pack will hunt throughout its territory as a unit. Juveniles stay with the pack for about two years, when they reach reproductive maturity, and may leave to find a mate and establish a new territory, or remain as a helper.
Humans are the biggest threat to this species. Mexican gray wolves were common about 100 years ago, but then many wolves were killed due to competition for the same resources with humans. In the late 1800's, once railroads were built, large numbers of settlers moved to the southwest. There was no protection at that time for wildlife. Many of the prey animals for this species were killed, and wolves were trapped, poisoned, or shot to protect people's livestock. Many wolves were also killed because fables (such as "Little Red Riding Hood") portray wolves as ferocious killers, or cunning tricksters, which does not reflect the true behavior of wolves.
According to the U.S. Fish and Wildlife Service, the total population size of the Mexican wolf in 2015 was 97 individuals in the wild. This includes 50 wolves in Arizona, 47 wolves in New Mexico and 7 breeding pairs in total. About 300 wolves in 48 different facilities live in the U.S. and Mexico. Mexican gray wolves are listed as Endangered by the Endangered Species Act (ESA) (NMFS NOAA Fisheries).