By Hollie Colahan, Executive Director of the Arizona-Sonora Desert Museum and Norberto J. (Bert) Castro, President and CEO of the Arizona Center for Nature Conservation/ Phoenix Zoo.
Header Image by Taylor Sparks, Mammalogy Keeper
For six decades, visitors to the Arizona-Sonora Desert Museum and Phoenix Zoo have been inspired by encounters with the Mexican grey wolf, by locking eyes (even for a moment), by hearing them howl, and by learning their story. The Museum, and our partner institutions, like the Phoenix Zoo, have been involved with recovery efforts from the very beginning. The Desert Museum was home to some of the ancestors of all living Mexican grey wolves and both the Museum and the Zoo have contributed wolves born in human care for release to the wild.
Driven to near extinction by the 1970’s, Mexican grey wolf numbers are starting to recover due to a science-driven reintroduction program supported by the majority of Arizonans, and carried out by federal, state, and tribal agencies. Unfortunately, some Arizona legislators want to end the program prematurely, nearly guaranteeing the disappearance of the Mexican wolf from the wild once again.
The Mexican grey wolf is the smallest, southernmost, rarest and most genetically distinct grey wolf. As a top predator, it plays a key role in the ecosystem, helping to keep the food web balanced. Thousands of these wolves once ranged throughout the southern US and northern Mexico, but by the 1970s they had been hunted, trapped, and poisoned to near oblivion. They were listed as endangered in 1976, and a species recovery plan was approved in 1982. The plan calls for two stable, genetically diverse populations, one in the U.S. and one in Mexico. The United State’s goal is to have a stable population over eight years averaging 320 wolves. The wolf count in the U.S. reached 317 in 2025, demonstrating success from many years of hard work. Unfortunately, the current count in Mexico falls far short of its goal.
The genetic diversity of the wild Mexican grey wolf population has also not yet recovered. All wild wolves are descended from only 7 founders, and a couple of these are over-represented due to their success in breeding. To increase diversity, wildlife managers introduce pups from captive-bred wolves into wild wolf dens, in a process called cross-fostering. Recent genetic analyses showed that a Phoenix Zoo cross-fostered wolf pup sired offspring born in the wild, providing hope that this strategy will continue to boost the wild population.
Wolves mostly eat elk, deer and other wild animals, helping to keep these populations in balance with the resources of the habitat. Some wolves prey upon livestock, impacting ranchers in the reintroduction area. Although cattle and sheep are much more likely to die from disease, complications during birthing, weather events, injury, and other predators, wolves have a disproportionate impact on some ranchers.
To compensate ranchers, a joint Federal/State program reimburses them for their losses. The program also provides funds to keep wolves away from cattle by hiring range riders and installing deterrent fencing and noise. These programs are making a positive impact: the number of depredations has not increased for several years despite the growing number of wolves.
The Mexican grey wolf recovery program is under attack at the state and federal levels. Bills pending in the Legislature and Congress would remove endangered species protections and prohibit critical program activities, such as introduction of wolf pups to foster genetic diversity.
Some of the rhetoric around these legislative efforts is not supported by data; for example, wolves have not attacked people, and the wolf population is not recovered. If legal protections are removed, wolf releases and cross-fostering would come to a halt. Monitoring would end, as would funding to compensate ranchers for losses and once again, wolves would be hunted, trapped and poisoned.
The Desert Museum and Phoenix Zoo do not want to be the only places where wolves can live in our state! Seek out science-based information on this topic from the Arizona Game and Fish Department, US Fish and Wildlife Service, and the websites of accredited zoos, like our institutions. Help us raise awareness of the plight of these magnificent and ecologically essential animals. We urge you to share your thoughts about protecting wild wolves with your communities and elected officials.
Learn more:
US Fish and Wildlife Program Annual Report 2024
AZ Game and Fish Program and Quarterly Reports
Reducing wolf-livestock conflict
Videos:
A history of the Mexican wolf and the effects of inbreeding on genetic diversity