Mexican wolf range: 90% in Mexico
by Cat Urbigkit, Pinedale Online!
October 4, 2017
A recent peer-reviewed scientific paper reaffirmed the historical range of the endangered Mexican wolf as being southeastern Arizona, southwestern New Mexico and the Sierra Madre Mountains in Mexico.
The paper was the featured article published in the July issue of The Journal of Wildlife Management. The authors included a skull morphologist, internationally known geneticist and an Arizona Game and Fish Department biologist.
In the peer-reviewed paper, they use ecological, physiographic and morphological data to clarify the Mexican wolf’s historical range.
"Most sources prior to the mid-1990s were in agreement and defined the historical range of the Mexican wolf as southeastern Arizona, southwestern New Mexico and portions of Mexico," the paper states. "Of this historical range, 10 percent occurs in the United States and the remainder in Mexico."
Historical data shows other subspecies of wolves roamed the Southwest, but each differed from the smaller, distinctive Mexican wolf, which was found in southern Arizona and New Mexico and southward deep into Mexico. The data also illustrate that Mexico is critical for wolf recovery, given that 90 percent of the animal’s historical range and extensive high-quality habitat is found south of the border.
To aid Mexican wolf recovery, the U.S. Fish and Wildlife Service included a 200-mile buffer north of the animal’s core historical range. The boundary was included in the 1996 federal environmental impact statement, which expanded the range into central Arizona and New Mexico.
Extending the historical range boundary northward would place Mexican wolves north of historical transitions in wolf body size, breaks in vegetation associations, barriers to gene flow and substantial differences in prey base, which help form and identify subspecies differences, the paper states.
The researchers wrote: "The historical range of the Mexican wolf should not be altered through the identification of similar habitat in other locations, the distribution of inadequately sampled molecular markers, or by theoretical arguments about movement capacity. Rather, it should respect the original descriptions that were made when the animal was still present on the landscape, and which are concordant with ecological relationships, physiography, morphology, and the principles of population genetics."
Additionally, introducing Mexican wolves too far north of their historical range runs the risk of "genetic swamping" by the larger Northern Rockies wolves, said AZGFD biologist Jim Heffelfinger, who co-authored the paper.
"Allowing establishment of Mexican wolves north of their historical range before they are recovered could lead to genetic swamping and the potential destruction of the uniqueness for which the Mexican wolf was listed," he said. "That would undo decades of efforts to return ‘El Lobo’ to the Southwest."
There were a minimum of 113 wolves in the wild in Arizona and New Mexico at the end of 2016, according to a survey by the Mexican Wolf Interagency Field Team. The survey found that there were 63 wolves in Arizona and 50 in New Mexico. This represents a more than doubling of the population since 2009.