Science guides geography of Mexican wolf recovery
AZGFD wolf experts correct some common misconceptions
Illustration above shows high-quality wolf habitat in the U.S. and Mexico (*source notation at bottom of article).
Over the past year, assertions have appeared in news releases and opinion pieces by some wolf advocacy groups and individuals that have been misleading to the public.
In this article, wolf experts with the Arizona Game and Fish Department provide information that addresses some of those assertions so that people have a truer picture of the facts about Mexican wolf recovery efforts.
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The geography of recovery of any endangered species is paramount in crafting a successful restoration of a native species. Some wolf advocates urge that the lead Mexican wolf recovery agencies focus recovery outside historical range. Historically, Mexican wolves existed in one linear population almost entirely (90%) in the Sierra Madre Occidental of Mexico, extending northward into the sky islands of southern Arizona and New Mexico. Some individuals dispersed northward into the high elevations of the Mogollon Rim and Gila National Forest, but no Mexican wolves were historically confirmed to be resident north of I-40. These advocacy groups suggest the agencies use outdated reintroduction recommendations, which are not supported by current Mexican wolf data, and which have been superseded by updated population viability, inbreeding, and habitat analyses.
These advocates urge recovery outside of historical range, suggesting that current historical range defined by the U. S. Fish and Wildlife Service, which is bounded to the north by Interstate 40, is arbitrary. Interstate 40 is not an arbitrary boundary for Mexican wolf recovery, it is a generous extension northward and based on the best historical, ecological, and genetic scientific information available. The best available science on Mexican wolf recovery shows that habitat north of I-40 is not needed for successful recovery. The Mexican wolf is physically, genetically, and ecologically different from other wolf subspecies which is why it was listed separately on the endangered species list and this uniqueness must be retained.
There are some that recommend artificially reconfiguring that single large distribution in historical range into a triangle of three separate populations entirely in the U.S., with two of those outside of historical range. This recommendation is purely a human construct based on a desire to see wolves in favored places and not a scientifically supported necessity for recovery of the Mexican wolf. This recurring assertion that recovery of the subspecies “requires” at least three separate populations was not the result of any data analysis and does not recognize the historical distribution of Mexican wolves prior to European settlement in the wolves’ range.
A comprehensive population viability analysis (PVA) supports the current recovery strategy with science-based evidence that binational Mexican wolf recovery will be successful within their historical range. Past recovery teams did not evaluate the potential of recovery in Mexico, dismissing the incredible potential of that country off-hand, and with it, the decades of hard work by our Mexican colleagues. Again, this ignores peer-reviewed and published work showing Mexico has more than 18,774 square miles of high-quality Mexican wolf habitat. The desire to repeatedly exclude Mexico from the recovery of their own wolves is without any scientific support and only impedes efforts to restore this important carnivore to its natural homelands.
Comprehensive, peer-reviewed scientific research published in 2024, using Mexican wolf pedigrees and reproductive data, shows that inbreeding depression is not impacting their recovery. Misinformation to the contrary can be easily refuted with publicly available scientific publications.
Allowing Mexican wolves to occupy habitat north of I-40 jeopardizes the very characteristics that led to their separate listing on the Endangered Species Act. Allowing Mexican wolves to hybridize with wolves from the Northern Rockies and Colorado, which originate from Canadian sources, is reckless and seriously jeopardizes the genetic integrity of the Mexican wolf from genetic swamping by the larger, more dominate subspecies. Hybridization between Mexican wolves and those with Canadian genes would create uncertainty as to the genetic integrity of the uniquely southwestern subspecies. The addition of genes and adaptations from animals that evolved in a very different northern environment is likely to irreversibly change the complex suite of adaptations to the desert southwest and Mexico that makes El Lobo unique.
Publicly available, peer-reviewed science and the protection of the integrity of the Mexican wolf should determine where Mexican wolves should be recovered. To demonstrate the success of recovery within historical range, the Mexican wolf, absent from the wild until 1998, now number at least 257 in the U.S. and retention of gene diversity exceeds levels projected in the most current PVA due to an aggressive pup fostering program conducted by the lead agencies for this subspecies’ recovery. Data points to the fact that recovery is occurring and at a faster rate than expected, supporting continued management in the currently defined historical range.
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*Source note: The peer-reviewed research article, "Rangewide habitat suitability analysis for the Mexican wolf (Canis lupus baileyi) to identify recovery areas in its historical distribution," was published in Diversity and Distributions, Vol. 27, No. 4 (April 2021), pp. 642-654. Authors: Enrique Martínez-Meyer, Alejandro González-Bernal, Julián A. Velasco, Tyson L. Swetnam, Zaira Y. González-Saucedo, Jorge Servín, Carlos A. López-González, John K. Oakleaf, Stewart Liley, James R. Heffelfinger.
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