To some, the phrase "Arizona jaguars" sounds like a football team. But the real animals--the biggest wildcats in North America--lived for millennia in what is now the southwestern United States.

Extirpated more than 60 years ago due to intense hunting, today the northernmost viable population of this species is located in the mountains of the Mexican state of Sonora, near the confluence of the Aros and Yaqui Rivers, just 120 miles south of the U.S. border. This population is the source of a handful of jaguars that have started to recolonize the American southwest, where suitable habitat for this species remains.

Now, through a five-year grant from the Philadelphia Zoo, a cross-border conservation effort gives Panthera onca more than a fighting chance at the northern edge of its range. The Wildlands Project, the Northern Jaguar Project, the Mexico-based conservation group Naturalia A.C., and the zoo have joined efforts to protect the Aros-Yaqui jaguar population and its habitat.

"We're working on a three-pronged approach," says Oscar Moctezuma, Director of Naturalia A.C., and a member of the Wildlands Project board of directors. "One, we are expanding an existing Mexican reserve for the cats by purchasing several key ranches that are part of their habitat. Two, we will expand our on-the-ground research to improve our basic knowledge of jaguar life history and habitat needs in the region. And, three, we will develop education programs to help local communities recognize that jaguars provide ecological and economic benefits and work on land management alternatives for local ranchers."

This conservation initiative will also identify linkages and key habitat for dispersal of the jaguars from this population to suitable habitat in Arizona and New Mexico and will promote the protection of these critical corridors. Additionally, the project provides research and educational opportunities for Philadelphia Zoo staff and patrons, building a constituency for jaguar conservation on both sides of the continent. (In a sign of things to come, zoos in Chicago, Arizona, Florida and elsewhere are eager to join this project; we'll keep you posted.)

Though the project is already improving prospects for these northernmost cats, their situation is precarious: the total population of the Aros-Yaqui region has been estimated at no more than 120 jaguars, and they are declining from poaching, illegal hunting, and habitat destruction. In the past four years, the killing of 27 jaguars (including females with cubs) has been documented in the region, pushing the viability of this "desert jaguar" population to the brink.

Equally worrisome, overall prospects for jaguars are tenuous. Over the past century, jaguar populations in Mexico and farther south have plummeted due to habitat loss and fragmentation, and adult and juvenile mortality have increased due to persecution by humans. As a result, jaguars are currently considered endangered throughout their range in Mexico and the U.S., and are listed on both the IUCN Red List of Threatened Species and the U.S. Endangered Species List.