The Endangered Mexican Gray Wolf
The Mexican gray wolf (Canis lupus baileyi) or “lobo” is the most genetically distinct lineage of gray wolves in the Western Hemisphere, and one of the most endangered mammals in North America. By the mid-1980s, hunting, trapping, and poisoning caused the extinction of lobos in the wild, with only a handful remaining in captivity. In 1998 the wolves were reintroduced into the wild as part of a federal reintroduction program under the Endangered Species Act. Today in the U.S., there is a single wild population comprising only 131 individuals - a slight increase from the 114 counted at the end of 2017.
In 2003 the WCC was accepted into the Species Survival Plan (SSP) for the critically endangered Mexican gray wolf and has played a critical role in preserving and protecting these imperiled species through carefully managed breeding and reintroduction. The goal of the Recovery Plan is to restore Mexican gray wolves to a portion of their ancestral range in the southwest United States and Mexico. To date, the WCC remains one of the three largest holding facilities for these rare species and three lobos from the WCC have been given the extraordinary opportunity to resume their rightful place on the wild landscape. The 28 Mexican gray wolves at the WCC occupy four enclosures in the WCC Endangered Species Facility. These enclosures are private and secluded, and the wolves are not on exhibit for the public. Wolves in the wild are naturally afraid of people so the WCC staff follows a protocol to have minimal human contact with the Mexican wolves. This will ensure they have a greater probability of being successful if they are released into the wild as part of the recovery plan.
The Mexican gray wolf (Canis lupus baileyi) is the southernmost and most genetically distinct subspecies of the North American gray wolf. From prehistoric to fairly recent times, the Mexican wolf, or lobo, ranged from central and northern Mexico to western Texas, southern New Mexico, and central Arizona.
Our knowledge of the Mexican wolf is sketchy because wild populations were effectively eliminated before they could be studied. Most of our information about the animal in the wild comes from trapper’s journals and reports. Adult Mexican wolves typically weigh 65-85 pounds, average 4.5-5.5 feet from nose to tail, and stand 28-32 inches at the shoulder. They breed from late January through early March, and give birth to an average of four to six pups about 63 days later.
Mexican wolves were found in a variety of southwestern habitats; however, they were not low desert dwellers. They preferred mountain woodlands, probably because of the favorable combination of cover, water, and available prey (deer, elk, javelina, rabbits, and small mammals). Like all wolves, the lobo is a social creature with an intricate system of communication and social structure. However, because the primary prey of Mexican wolves is smaller than the moose and caribou hunted by northern wolves, wolf pack sizes were probably smaller as well. A typical pack of five or six animals might consist of an adult pair and their offspring, with a territory encompassing up to several hundred square miles. Hunting behavior and strategies would vary with terrain, and prey size and availability. Wolves can and do occasionally kill livestock, particularly vulnerable young animals. 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.
Mexican wolves were common throughout their range in the mid-1800s. Toward the turn of the century, high cattle stocking rates and low 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 and poisoned by both private individuals and government agents. Bounties were paid. By the mid-1900s, Mexican wolves had been effectively eliminated from the United States, and Mexican populations were severely reduced.
The Mexican wolf was listed by the U. S. Fish and Wildlife Service as an endangered species in May 1976, and was considered extinct in the wild up until their reintroduction in 1998 into Arizona and New Mexico. A few may remain in the wild in Mexico; however, their presence there has not been confirmed since 1980. Reports of Mexican wolf sightings are occasionally received from the United States/Mexico border areas of Arizona and New Mexico, and Texas, but none have been verified to date.
RECOVERY EFFORTS AND CAPTIVE BREEDING
The Mexican Wolf Recovery Team was founded by the USFWS in August 1979. The Team prepared the Mexican Wolf Recovery Plan, which contains the following objective:
“To conserve and ensure the survival of C. l. baileyi by maintaining a captive breeding program and re-establishing a viable, self-sustaining population of at least 100 Mexican wolves in the middle to high elevations of a 5,000-square mile area within the Mexican wolf’s historic range.”
The Endangered Species Act requires the USFWS to develop and implement plans for the conservation and survival of listed species. The objective is to recover species to secure population levels, maintain those levels, and then remove them from the endangered list. Under an agreement between the United States and Mexico, five Mexican wolves (four males and one pregnant female) were captured between 1977-1980 in Durango and Chihuahua. These wolves were transferred to the United States to establish a certified captive breeding program that is now managed for the Service under the American Zoo and Aquarium Association’s Species Survival Plan Program (SSP).
In July 1995, two additional lineages of captive Mexican wolves were approved for addition to the SSP breeding program. The Ghost Ranch population in the United States and the Aragon population in Mexico City, both maintained in captivity since the 1960s, were previously uncertified because of uncertainties about their origins. However, recent advances in DNA analysis techniques have been applied to the populations, and they have been determined to be pure Mexican wolves. These lineages added 4 new founders and 33 individuals, to the total captive population.
REESTABLISHMENT OF WILD POPULATIONS
In March 1997, the Secretary of the U. S. Department of the Interior approved a plan to restore Mexican wolves to a portion of its historic range in Arizona and New Mexico. The final environmental impact statement was completed in December 1996 after 14 public meetings, three formal public hearings, and analysis of over 18,000 comments from other agencies, organizations, and citizens.
In March 1998 the USFWS and its cooperators, Arizona Game and Fish Department, New Mexico Department of Game and Fish, USDA Wildlife Services, released three family groups consisting of 11 Mexican wolves into the primary recovery zone on public lands within the Apache National Forest in eastern Arizona. Two additional wolves were released later that year. The Service and cooperators released three additional breeding pairs in 1999. Additional family groups will be released each year until natural reproduction sustains wild population growth.
Reintroduced wolves are allowed to disperse throughout secondary recovery zones in the Apache National Forest and the adjacent Gila National Forest in New Mexico. The two forests are designated the Blue Range Wolf Recovery Area.
NONESSENTIAL EXPERIMENTAL POPULATION
Released wolves and their offspring are designated a nonessential experimental population in a special regulation (rule), which defines management guidelines, including provisions for removal of wolves that depredate livestock. Wolves are not allowed to establish territories outside recovery area boundaries. Dispersing wolves will be recaptured and relocated back to the recovery area or returned to captivity.
The Wolf Conservation Center (WCC) participates in the federal Species Survival Plan (SSP) recovery programs for the Mexican gray wolf and the red wolf, two of the rarest mammals in North America. Both species at one time were completely extinct in the wild.
Since 2003 the WCC has played a critical role in preserving and protecting these imperiled species with through carefully managed breeding and reintroduction. To date, the WCC remains one of the three largest holding facilities for these rare species and four wolves from the Center have been given the extraordinary opportunity to resume their rightful place on the wild landscape.
What is a Species Survival Plan?
A Species Survival Plan (SSP) is a breeding and management program designed to ensure the long-term sustainability of captive-based animal populations. It’s a coordinated effort among zoos, organizations like the Wolf Conservation Center, U.S. Fish and Wildlife Service, Mexico’s Fish & Wildlife Agencies and managed under the Association of Zoos and Aquariums (AZA).
The MWSSP is a bi-national initiative between the U.S. and Mexico whose primary purpose is to support the reestablishment of the Mexican wolf in the wild in both the United States and Mexico through captive breeding, public education and research.
As a participant in the MWSSP the WCC:
- House and care for the wolves
- Participate in the captive breeding program
- Make observations and recommendations for release
- Conduct semen and oocyte collection for future use via artificial insemination
- Raise awareness and encourage public participation
FWS’s Mexican Wolf Recovery Program: Progress Reports
- 2017 U.S. Mexican Wolf Population Survey Completed
- Mexican Gray Wolf Recovery Plan First Revision November 2017
- 2015 Progress Report
- 2014 Progress Report
- 2013 Progress Report
- Addendum to the 2012 Mexican Wolf Minimum Population Estimate
- 2012 Progress Report with Addendum
- Addendum to the 2011 Mexican Wolf Minimum Population Estimate
- 2011 Progress Report with Addendum
- 2010 Progress Report
- 2009 Progress Report
- 2008 Progress Report
- 2007 Interagency Field Team Annual Report
- 2006 Annual Progress Report
- 2005 Annual Progress Report
- 2004 Annual Progress Report
- 2003 Annual Progress Report
- 2002 Annual Progress Report
- 2001 Annual Progress Report
MEXICAN WOLF ARTICLES
- 2019 Dozen Zoo-Born Mexican Wolf Pups Find New Homes in Wild After Successful Fostering Effort, Part of Ongoing Wolf Recovery Program, FWS, June 2019
- 2019 Mexican gray wolf numbers rise, but long-term viability still a concern by Andrew Howard, Cronkite News, April 2019
- 2018 Court Throws a Lifeline to Endangered Mexican Gray Wolf - Judge takes Fish and Wildlife Service to task for ignoring best available science, by Elizabeth Miller, Sierra Magazine, April 2018
- 2017 Critics pan wolf plan Recovery plan for Mexican wolf promises no new U.S. habitat. States are pleased; some biologists are dismayed by Cally Carswell, Science Magazine
- 2006 The Bureaucratically Imperiled Mexican Wolf by Anthony Povilitis, David R. Parsons, Michael J. Robinson, and C. Dusti Becker
MEXICAN WOLF RESEARCH
- 2019 Biological and Sociopolitical Sources of Uncertainty in Population Viability Analysis for Endangered Species Recovery Planning, Carroll et al, Scientific Reports
- 2019 Evaluating the Taxonomic Status of the MEXICAN GRAY WOLF and the RED WOLF, a Consensus Study Report of the National Academies of Science
- 2018 Rewilding The World's Large Carnivores, Christopher Wolf, William Ripple, Royal Society
- 2018 Genetic rescue, not genetic swamping, is important for Mexican wolves. (Letter to the Editor) by Philip Hedrick, Robert Wayne, Richard Fredrickson
- 2018 Perils of recovering the Mexican wolf outside of its historical range. (Perspective) by Odell, Heffelfinger, Rosenstock, Bishop, Liley, González-Bernal, Velasco, Martínez-Meyere
- 2015 Re-defining historical geographic range in species with sparse records: Implications for the Mexican wolf reintroduction program by Hendricks, Callas, Sesink, Clee, Figura, Harrigan, Wayne, Pollinger, and Freedman
- 2015 Mexican Wolves Are a Valid Subspecies and an Appropriate Conservation Target by Fredrickson, Hedrick, Wayne, vonHoldt, and Phillips
- 2015 Live Births from Domestic Dog (Canis familiaris) Embryos Produced by In Vitro Fertilization via the journal Public Library of Science ONE
- 2015 Cross-Fostering in Gray Wolves (Canis lupus) by Inger Scharis and Mats Amundin
- 2014 “Use it or Lose it”: Characterization, Implications, and Mitigation of Female Infertility in Captive Wildlife"
- 2013 Developing Metapopulation Connectivity Criteria from Genetic and Habitat Data to Recover the Endangered Mexican Wolf by Carlos Carroll, Richard Fredrickson, and Robert C Lacy
- 2013 Tolerance by Denning Wolves, Canis lupus,to Human Disturbance by Richard P. Thiel Samuel Merrill and L. David Mech
- 2011 Genetics and wolf conservation in the American West: lessons and challenges by R Wayne and P Hedrick
- 2010 Mexican wolves, elk, and aspen in Arizona: Is there a trophic cascade? by Robert L. Beschta, William J. Ripple
- 2007 Genetic rescue and inbreeding depression in Mexican wolves by Richard J. Fredrickson, Peter Siminski, Melissa Woolf and Philip W. Hedrick
- 2006 Diets of Free-Ranging Mexican Gray Wolves in Arizona and New Mexico
- 2006 Reintroduction of the Mexican wolf (Canis lupus baileyi) to the Southwestern United States: An economic perspective by Timm Kroeger, Frank Casey, and Chris Haney
- 2008 "Where the Wild Things Were: Life, Death, and Ecological Wreckage in a Land of Vanishing Predators." William Stoltzenburg
- 2005 "Predatory Bureaucracy: The Extermination of Wolves and the Transformation of the West" Michael J. Robinson
- Cows Kill More People in the U.S. Annually than Wolves do... via Defenders of Wildlife
- 2013 Mexican Gray Wolves 2013:The Time For Recovery Is Now via Defenders of Wildlife
- Livestock and Wolves: A Guide to Nonlethal Tolls and Methods to Reduce Conflicts
Geneticist Rich Fredrickson explains the importance of releasing more endangered Mexican gray wolves from the captive population into the wild.