Reintroduction of the Mexican wolf nears 25th anniversary

Mark Altaweel

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The Mexican wolf (Canis lupus baileyi), the rarest subspecies of the Gray wolf, was once common in the southwest United States and Mexico, but went largely extinct in the wild by the 1970s mostly because the animals were hunted or shot due to livestock expansion. In 1976, the Mexican wolf was listed as endangered and a binational captive breeding program was begun. Almost 25 years ago in 1998, the U.S Fish and Wildlife Service began to release captive Mexican wolves in an areas designated as the Mexican Wolf Experimental Population Area (MWEPA) in Arizona and New Mexico.[1]

Historic range of the Mexican wolf

The historic range of the Mexican wolf primarily encompassed regions in southeastern Arizona, southern New Mexico, and northern Mexico, and it possibly extended into western Texas.

A grayscale map showing the historical range of the Mexican wolf.
The historic range of the Mexican wolf. Map: Heffelfinger, J. R., Nowak, R. M., & Paetkau, D. (2017). Clarifying historical range to aid recovery of the Mexican wolf. The Journal of Wildlife Management, 81(5), 766-777., CC BY 4.0

What is the Mexican Wolf Experimental Population Area (MWEPA)?

The Mexican Wolf Experimental Population Area (MWEPA) is a designated region in Arizona and New Mexico, established by the U.S. federal government for the conservation and recovery of the Mexican wolf, a subspecies of the gray wolf. The MWEPA extends from south of Interstate Highway 40 to the international border with Mexico and includes specific zones labeled as 1, 2, and 3.

The MWEPA is constrained to the the mountains and valleys of southern Arizona and New Mexico and encompasses a variety of habitats suitable for the wolves, ranging from forested areas to meadows and arid regions.


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Map showing the Mexican wolf experimental population area.
Mexican wolf experimental area. Map: USFWS.

Recovery of Mexican wolf populations

Similar to the Gray wolves of Yellowstone and areas of the West in the United States, the Mexican wolf has begun to recover and roam once again in its historic ranges. The U.S. Fish and Wildlife Service reported in February of 2023 that the population of Mexican wolves in Arizona and New Mexico has surpassed 200 for the first time since their reintroduction, reaching a minimum of 241 in 2022. This marks a 23% increase from 2021 and a significant growth since 2017. The report highlights a minimum of 59 wolf packs, 121 pups born in 2022 with a 67% survival rate, and an enhanced cooperative conservation effort between various agencies.

A male Mexican wolf stands on a snow covered log.
A male Mexican wolf, M1855. M1855 was born 2019 as part of the Dark Canyon pack in New Mexico. Photo: Mexican Wolf Interagency Field Team, USFWS, public domain.

Expanding past the MWEPA

Recently, a female Mexican wolf in search of a mate was even seen north of MWEPA as reported by the USFWS, showing the captivity and release program started in the 1970s is beginning to lead to a very successful recovery for the wolf.[2] The importance of this recovery has implications for the wider ecology, such as in limiting the number of grazing animals that may damage natural habitats when they reach high population levels.

Overall, the successful Mexican wolf reintroduction means the population will likely now expand from New Mexico and Arizona, potentially reaching other Western states and other regions in Mexico. The problem this creates is there may be new challenges to the Mexican wolf as it expands that could threaten some of the initial successes. 

Predicting areas the Mexican wolf may colonize is important. Information and research that helps to determine dispersal dynamics can be used to  reduce hybridization and disease transmission, mitigate or limited wolf–livestock conflicts that led to the Mexican wolf being killed in great numbers previously, and satisfy different stakeholders and society. This is also important because planning and averting potential problems caused by wolf expansion will help to keep tolerance and acceptance of the wolf sustained in the long-term.[3] 

Competition with other wolves

One potential threat to the recovery of the Mexican wolves is not hunters or even ranchers, but other wolf populations. The Northwestern wolf has also been recovering and migrating more to the south from Canada and the Western United States. This is another subspecies of Grey wolf and it is a much larger one than the Mexican wolves. One possibility is if the Northwestern wolf expansion and Mexican expansion are too successful, then the Northwestern wolf population may both breed and compete with the Mexican wolf population. Eventually, the Northwestern wolf may become more dominant and overtake the range of the Mexican wolf given its larger size and overall more powerful form. There might be a need to make sure the ranges of these two wolves do not overlap.[4]

According to the US Fish and Wildlife Service, there are at least 59 known wolf packs, with 40 of these in New Mexico. As mentioned previously, survival rates of wolves born have been documented to be around 67 percent, which is high enough to help numbers grow steadily.[5] The expansion of the Mexican wolf, along with other sub-species of wolves will continue to be important, even as hybridization could potentially threaten some of this success. Wolves are seen as keystone species that enable the wider ecosystem to thrive, including plants and animals of all sizes. Ecosystem balance is increasingly seen as not only critical for plant and animal species but is now increasingly seen as important to wider attempts in limiting ecological breakdown. Wolves, including the Mexican wolf, will play a critical role in maintaining and sustaining important ecological balance across much of the Western United States.[6]

For now, the Mexican wolf represents another very successful conservation effort that has seen the expansion of various subspecies of Grey wolf populations. There are emerging problems that could inadvertently harm some subspecies or even threaten current success of release programs, but the conservation efforts of the Mexican wolf can be considered a success that can serve as a model for other predator conservation efforts in the United States and abroad.

References

[1]    For more on the Mexican wolf’s background and captivity and release program, see: https://www.fws.gov/program/conserving-mexican-wolf

[2]    The sighting of a female Mexican wolf north of Interstate 40 represents one of the first times since the release program began that this wolf subspecies has expanded beyond the borders of the MWEPA: https://www.fws.gov/press-release/2023-11/mexican-wolf-located-north-interstate-40-northwest-new-mexico.

[3]    For more on predicting wolf population expansion and its relevance for long-term conservation, see:  Ausband, David E, and L David Mech. 2023. “The Challenges of Success: Future Wolf Conservation and Management in the United States.” BioScience 73(8): 587–91.

[4]    For more on the expanding ranges of wolves and how the Northwestern wolf may threaten the Mexican wolf, see:  Odell, Eric A. et al. 2018. “Perils of Recovering the Mexican Wolf Outside of Its Historical Range.” Biological Conservation 220: 290–98.

[5]    For more on recent statistics on the Mexican wolf population in MWEPA, see: https://www.fws.gov/press-release/2023-02/mexican-wolf-numbers-soar-past-200.

[6]    For more on how wolves help ecosystems retain their balance and help other plant and animal species to thrive, see: https://www.livingwithwolves.org/about-wolves/why-wolves-matter/.

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About the author
Mark Altaweel
Mark Altaweel is a Reader in Near Eastern Archaeology at the Institute of Archaeology, University College London, having held previous appointments and joint appointments at the University of Chicago, University of Alaska, and Argonne National Laboratory. Mark has an undergraduate degree in Anthropology and Masters and PhD degrees from the University of Chicago’s Department of Near Eastern Languages and Civilizations.