Mexican wolf
The Mexican wolf, also known as the lobo mexicano is a subspecies of gray wolf native to eastern and southeastern Arizona and western and southern New Mexico and fragmented areas of northern Mexico. Historically, the subspecies ranged from Southern California south into Baja California, east through the Sonora and Chihuahua Deserts and into West Texas.
Its ancestors were likely among the first gray wolves to enter North America after the extinction of the Beringian wolf, as indicated by its southern range and basal physical and genetic characteristics. Though once held in high regard in Pre-Columbian Mexico, Canis lupus baileyi became the most endangered gray wolf subspecies in North America, having been extirpated in the wild during the mid-1900s through a combination of hunting, trapping, poisoning and the removal of pups from dens, mainly out of fear, by livestock herders and ranch owners. After being listed officially under the Endangered Species Act in 1976, both the United States and Mexico collaborated to capture all lobos remaining in the wild. This extreme preventative measure would end up forestalling their imminent extinction; five wild Mexican wolves were captured, alive, in Mexico between 1977 and 1980. Once settled in captive rescue centers, this group of wolves would prove vital in starting a captive breeding program. Thanks to these preemptive measures, captive-bred Mexican wolves were released into recovery areas in Arizona and New Mexico beginning in 1998 in an effort to recolonize the animals' historical range.
As of 2025, there are at least 286 wild Mexican wolves in the US and 45 in Mexico, and 380 in captive breeding programs, up from the 11 individuals that were released in Arizona in 1998. These numbers represent a minimum as the survey only counts wolf sightings confirmed by Interagency Field Team staff.
Description
The Mexican wolf is the smallest of North America's gray wolf subspecies, weighing with an average height of and an average length of. It is similar to the Great Plains wolf, albeit distinguishable by a smaller, narrower skull and darker, more variable pelage.Taxonomy
The Mexican wolf was first described as a distinct subspecies in 1929 by Edward Nelson and Edward Goldman on account of its small size, narrow skull and dark pelt. This wolf is recognized as a subspecies of Canis lupus in the taxonomic authority Mammal Species of the World . In 2019, a literature review of previous studies was undertaken by the National Academies of Sciences, Engineering, and Medicine. The position of the National Academies is that the historic population of Mexican wolf represents a distinct evolutionary lineage of gray wolf, and that modern Mexican wolves are their direct descendants. It is a valid taxonomic subspecies classified as Canis lupus baileyi. Genetic analyses have confirmed that the Mexican wolf is the most genetically distinct subspecies of gray wolf in North America.Lineage
Gray wolves migrated from Eurasia into North America 70,000–23,000 years ago and gave rise to at least two morphologically and genetically distinct groups. One group is represented by the extinct Beringian wolf and the other by the modern populations. One author proposes that the Mexican wolf's ancestors were likely the first gray wolves to cross the Bering Land Bridge into North America during the Late Pleistocene after the extinction of the Beringian wolf, colonizing most of the continent until pushed southwards by the newly arrived ancestors of the Great Plains wolf.A haplotype is a group of genes found in an organism that are inherited together from one of their parents. Mitochondrial DNA passes along the maternal line and can date back thousands of years. A 2005 study compared the mitochondrial DNA sequences of modern wolves with those from thirty-four specimens dated between 1856 and 1915. The historic population was found to possess twice the genetic diversity of modern wolves, which suggests that the mDNA diversity of the wolves eradicated from the western US was more than twice that of the modern population. Some haplotypes possessed by the Mexican wolf, the Great Plains wolf, and the extinct Southern Rocky Mountain wolf were found to form a unique "southern clade". All North American wolves group together with those from Eurasia, except for the southern clade which form a group exclusive to North America. The wide distribution area of the southern clade indicates that gene flow was extensive across the recognized limits of its subspecies.
In 2016, a study of mitochondrial DNA sequences of both modern and ancient wolves generated a phylogenetic tree which indicated that the two most basal North American haplotypes included the Mexican wolf and the Vancouver Island wolf.
In 2018, a study looked at the limb morphology of modern and fossil North American wolves. The major limb bones of the dire wolf, Beringian wolf, and most modern North American gray wolves can be clearly distinguished from one another. Late Pleistocene wolves on both sides of the Laurentide Ice Sheet — Cordilleran Ice Sheet possessed shorter legs when compared with most modern wolves. The Late Pleistocene wolves from the Natural Trap Cave, Wyoming and Rancho La Brea, southern California were similar in limb morphology to the Beringian wolves of Alaska. Modern wolves in the Midwestern US and northwestern North America possess longer legs that evolved during the Holocene, possibly driven by the loss of slower prey. However, shorter legs survived well into the Holocene after the extinction of much of the Pleistocene megafauna, including the Beringian wolf. Holocene wolves from Middle Butte Cave and Moonshiner Cave in Bingham County, Idaho, were similar to the Beringian wolves. The Mexican wolf and pre-1900 samples of the Great Plains wolf resembled the Late Pleistocene and Holocene fossil gray wolves due to their shorter legs.
Ancestor
In 2021, a mitochondrial DNA analysis of North American wolf-like canines indicates that the extinct Late Pleistocene Beringian wolf was the ancestor of the southern wolf clade, which includes the Mexican wolf and the Great Plains wolf. The Mexican wolf is the most basal of the gray wolves that live in North America today.Hybridization with coyotes and other wolves
Multiple recent studies using morphological and genetic datasets have concluded that Mexican wolves hybridized in clinal fashion with other wolf subspecies where both met. The Mexican Wolf Recovery plan currently plans to manage against such occurrence in the event that Northern Rockies and Mexican wolves come into contact to protect against a genetic swamp. While the purity of Mexican wolf DNA composition is important for the time being, a natural, free-ranging wolf population on a continental scale would include hybridization between different subspecies to occur freely. Mexican wolves are under considerable threat from low genetic diversity and inbreeding because all wild Mexican wolves share on average the same amount of genes as full siblings do.Unlike eastern wolves and red wolves, the gray wolf species rarely interbreeds with coyotes in the wild. Direct hybridizations between coyotes and gray wolves was never explicitly observed. Nevertheless, in a study that analyzed the molecular genetics of the coyotes as well as samples of historical red wolves and Mexican wolves from Texas, a few coyote genetic markers have been found in the historical samples of some isolated individual Mexican wolves. Likewise, gray wolf Y-chromosomes have also been found in a few individual male Texan coyotes. This study suggested that although the Mexican gray wolf is generally less prone to hybridizations with coyotes compared to the red wolf, there may have been exceptional genetic exchanges with the Texan coyotes among a few individual gray wolves from historical remnants before the population was completely extirpated in Texas. However, the same study also countered that theory with an alternative possibility that it may have been the red wolves, who in turn also once overlapped with both species in the central Texas region, who were involved in circuiting the gene-flows between the coyotes and gray wolves much like how the eastern wolf is suspected to have bridged gene-flows between gray wolves and coyotes in the Great Lakes region since direct hybridizations between coyotes and gray wolves is considered rare.
In tests performed on a sample from a taxidermied carcass of what was initially labelled as a chupacabra, mitochondrial DNA analysis conducted by Texas State University professor Michael Forstner showed that it was a coyote. However, subsequent analysis by a veterinary genetics laboratory team at the University of California, Davis concluded that, based on the sex chromosomes, the male animal was a coyote–wolf hybrid sired by a male Mexican wolf. It has been suggested that the hybrid animal was afflicted with sarcoptic mange, which would explain its hairless and blueish appearance.
A study in 2018 that analyzed wolf populations suspected to have had past interactions with domestic dogs found no evidence of significant dog admixture into the Mexican wolf. Another study in the same year was published in the journal PLOS Genetics which analyzed the population genomics of gray wolves and coyotes from all over North America. This study detected the presences of coyote admixtures in various western gray wolf populations, all previously thought to be free of coyote-introgression, and found that the Mexican wolves carry 10% coyote admixture. The study's author also suggests that the admixture from coyotes may have also played a role in the basal phylogenetic placement of this subspecies.
Distribution
Early accounts of the distribution of the Mexican wolf included southeastern Arizona, southwestern New Mexico, and western Texas in the U.S., and the Sierra Madre Occidental in Mexico. This past distribution is supported by ecological, morphological, and physiographic data. The areas described coincide with the distribution of the Madrean pine–oak woodlands, a habitat which supports Coues' white-tailed deer that were historically the Mexican wolf's main prey.In 2014, a haplotype found in modern captive Mexican wolves, lu33, was found in a wolf specimen from the Providence Mountains. There are records of a Mexican wolf pack consisting of seven individuals distributed across Peters Canyon, Limestone Canyon, and Precitas Canyon in the Santa Ana Mountains, the only one known from the mountain range.
Today, following their reintroduction and conservation, Mexican wolves are widely distributed across over 40,000 km2 of western New Mexico and eastern Arizona, largely coinciding with the Apache-Sitgreaves and Gila National Forests and the surrounding areas. Under the current Mexican Wolf Recovery Plan, this area is categorized as predominantly Wolf Management Zone 1. This plan designates the wolf experimental population area as all of New Mexico and Arizona, south of Interstate Highway 40. Wolves sometimes disperse outside of this area, though they are sometimes caught and returned to the management zones. In 2024, a breeding pair of wolves were released into Arizona's Peloncillo Mountains, which are in Wolf Management Zone 2. A small population of wolves have also been reintroduced to Sonora and Chihuahua, Mexico.