Mexican Gray Wolf - Overview

The Mexican gray wolf (Canus lupus baileyi, often called the Mexican wolf) is a small, rare, genetically distinct subspecies of the gray wolf [1].  The Mexican wolf is native to the Sierra Madre Mountains of Mexico, with its home range extending into southeastern Arizona [1].  By 1970, private individuals and federal and state governments on both sides of the United States Mexico border had nearly eradicated the species due to wolf conflicts with livestock and other human interests [1].  Recognizing the need to save the species, the two countries worked together to capture the last remaining wild Mexican wolves [2].  The five wild wolves along with two wolves in captivity founded the first lineage of the certified captive Mexican wolf population [2]. 

In accordance with the 1982 Mexican Wolf Recovery Plan [3], the U.S. Fish and Wildlife Service prepared the final Environmental Impact Statement (EIS) in 1996 [4].  The EIS proposed to reintroduce a self-sustaining population of at least 100 Mexican gray wolves into a portion of the subspecies’ historic home range [4].  The EIS proposed releasing the Mexican wolves from the captive breeding program into the Apache National Forest in eastern Arizona and allowing them to expand into the Gila National Forest in western New Mexico [4].  This area is called the Blue Range Wolf Recovery Area [4]. Wolves within this region are designated as a nonessential experiment population (10j) under federal law [4].  On May 28, 1998, the first captive raised Mexican wolves were released in the Recovery Area [2].

Following the first release, wolves organized themselves into packs and produced wild-born wolves the following summer [2].  By 2005, the need to release captive wolves had declined [5].  By 2010, nearly all wolves in the wild were born in the wild [5].  As of 2013, at least 83 wolves were counted roaming in Arizona and New Mexico and there are between 250 and 300 Mexican wolves in the captive breeding program [6].

Wolves in the wild are closely monitored by the Interagency Field Team (IFT).  The IFT monitors their genetic diversity [7,8], diet (80-90% elk) [7,9], movements (using radio telemetry collars) [7,10], mortalities (99 between 1998 and 2013) [7,11], and depredations on livestock [7] in addition to drafting annual working reports and other documentation required by law.  Given the labor and time intensive management activities, it is estimated that federal and state governments have contributed a minimum of $28.8 million between 1977 and 2012 in addition to private investments and volunteer costs [12].

In 2013, the U.S. Fish and Wildlife Service proposed two changes related to the Mexican Wolf Recovery Plan.  The first aims to delist the gray wolf from the endangered species list and add the Mexican gray wolf to the endangered species list in order to maintain protections for the subspecies [13].  The second proposal aims to expand the areas where wolves are allowed to establish to avoid translocations and enlarge the release zone for captive wolves to avoid overlapping pack territories and interspecies strife [14].

Not all people are enthusiastic over the Mexican Wolf Recovery Program.  Some big game hunters, big game guides, and livestock operators view the reintroduced wolf population as a pest.  For hunters and guides, there are concerns on whether elk populations will decline with an increase in the wolf population since Mexican wolves feed primarily on elk [9,15].  Wolves occasionally prey livestock, which harms livestock and hurts ranchers financially.  Livestock that witness or are attacked by wolves tend to show signs of stress (reduced reproduction, decreased weight gain), that cause financial hardship to ranchers already dealing with small profit margins [16,17].  In an attempt to address this issue, the Mexican Wolf / Livestock Coexistence Council was created in 2011.  The Coexistence Council includes individuals affected by the wolf recovery program.  The goal of the Council is to distribute compensation for livestock depredations and work toward a Pay for Wolf Presence program [18,19]. 

Wolves will continue to spark debate.  Federal and state agencies are committed to the recovery of the Mexican gray wolf, as required by law.  The challenge has been and will continue to be balancing the needs of wild wolves, wildlife, and human interests.

References

  1. Natural History of the Mexican Gray Wolf - Description of the Mexican gray wolf, including animal description, social interactions, and habitats.
  2. Mexican Wolf Recovery Efforts - Background information about the Mexican wolf, including their history, endangered species listing, the captive breeding program (start of the recovery efforts), and reintroduction into the wild.
  3. 1982 Mexican Wolf Recovery Plan 
  4. Reintroduction of the Mexican Wolf within its Historic Range in the Southwestern United States 
  5. Initial Release Numbers - Outlines initial releases and translocations of wolves between 1998 and 2013.
  6. Population Statistics Minimum population estimate, minimum breeding pair estimate, and population estimate numbers depicted per state within the Blue Range Wolf Recovery Area, 1998 to 2013.
  7. 2012 Progress Report - At the year's end, at least 75 wolves in 13 packs are in the wild.
  8. Cross-Fostering to Promote Genetic Diversity - News Release stating that the Interagency Field Team has conducted the first cross-fostering of the Mexican wolf pups in the wild.
  9. Genetic Analysis of Mexican Wolf Scat -  Genetic analysis of scats to identify prey remains in scats of Mexican wolves and two sympatric carnivores
  10. Number of Radio-Collared Wolves - As of December 31, 2013, 46 wolves wear radio telemetry collars out of 93 wolves (minimum population), which is 55% of the population.
  11. Mortality Statistics - Causes of documented Mexican wolf mortalities in the Blue Range Wolf Recovery Area, Arizona and New Mexico, 1998-2013. Management-related permanent removals, including lethal control, are not included in this table.
  12. Estimated Funds Expended by Lead Agencies for Mexican Wolf Recovery and Reintroduction - Summary provides the best available information on costs to date of the primary agencies involved in the Mexican wolf recovery and reintroduction.  Estimates are not an exact accounting of actual costs, simply the best available estimates.
  13. Removing the Gray Wolf (Canis lupus) from the List of Endangered and Threatened Wildlife and Maintaining Protections for the Mexican Wolf (Canis lupus baileyi) by Listing it as Endangered
  14. Proposed Revision to the Nonessential Experimental Population of the Mexican Wolf
  15. Mexican Wolf Impacts on Deer and Elk Populations in Arizona 1998 through 2012 - The Mexican gray wolf population has not causes changes to elk calf recruitment, mule deer recruitment, total elk hunting licenses available, or hunter success. 
  16. Reestablishment of the Mexican Gray Wolf: The Economics of Depredation - Discusses the economic impacts of the wolf recovery program on livestock operations.  Evaluates whether there is a disproportionate burden or economic impact on a few individuals for the good of the American society.
  17. Crying Wolf? A Spatial Analysis of Wolf Locations and Depredations on Calf Weight - Ranchers in Montana that experienced a confirmed livestock depredation by wolves had a negative and statically significant impact (~22 pounds) on the average calf weight across the herd, possibly due to inefficient foraging behavior or stress to the mother cows.
  18. Depredation Companion Guidelines - Outlines Depredation Compensation Guidelines to compensate livestock producers for wolf depredations.  
  19. Mexican Wolf / Livestock Coexistence Council: 2014 Strategic Plan - The Mexican Wolf / Livestock Coexistence Council is an organization dedicated to supporting viable ranching, self-sustaining wolf populations, and healthy western landscapes in the American southwest.  The strategic plan was collaboratively developed by the Council to articulate the wide range of perspectives around wolf recovery efforts.