Endangered Mount Graham Red Squirrels Thrive Thanks to Arizona Organizations

PHOENIX – The Mount Graham red squirrel, an endangered species native to Arizona’s Pinaleño Mountains, has faced significant challenges for over 25 years, struggling against a declining population.

First classified as endangered in 1987, the population has fluctuated between 35 and 550 individuals. Habitat loss, wildfire events, and competition for food have been critical factors in their decline. Recent coordinated efforts involving the Arizona Game and Fish Department, the University of Arizona, the Phoenix Zoo, and the U.S. Forest Service have led to a notable increase in their numbers, with estimates suggesting the population has risen from 144 to approximately 233 squirrels over the past year.

“It was fantastic,” said Holly Hicks, a small mammal project coordinator with the Arizona Game and Fish Department. “We all just felt such relief to know that the population can recover after such a devastating wildfire.” This recovery is especially significant as it marks the first population count over 200 since 2017, following the destructive Frye Fire that nearly wiped them out.

The Frye Fire in the summer of 2017 drastically reduced their habitat, leaving only about 35 squirrels alive. “That first year after the fire, morale was low,” Hicks recounted, reflecting on the emotional toll of the event. “To see something like that come through is devastating for those committed to conservation.”

Despite some recovery efforts, the Mount Graham red squirrels continue to face threats, primarily from competition with Abert’s squirrels, a non-native species introduced in the 1940s. Abert’s squirrels possess larger habitats and compete for the same food sources, exacerbating the struggle for the red squirrels. Much of their essential habitat comprises spruce and fir trees, which were largely destroyed in the Frye Fire.

“I think red squirrels are very resilient,” noted Bret Pasch, an associate professor at the University of Arizona’s Wildlife Conservation and Management program. “If you’re going to have an endangered species, red squirrels are a good one to have because they can really tolerate high human footprint.” His remarks highlight the complex interaction between conservation efforts and human activity in the area.

Human presence on Mount Graham has stirred controversy in the past, particularly surrounding the Mount Graham International Observatory built in the late 20th century. While the observatory did occupy some critical habitats, it also played a role in mitigating wildfire risks, according to Hicks. “When there are structures in place, that’s where the first efforts go in to protect the space,” she explained.

The geography of southern Arizona ensures that the Mount Graham red squirrel’s range remains confined, as expansive stretches of the Sonoran Desert isolate each mountain range from one another. This isolation further complicates the species’ long-term survival.

In an effort to safeguard this species, the Phoenix Zoo initiated a captive breeding program in 2014, aimed at creating a healthy off-site population that could be reintroduced into the wild. Currently, the program houses two male and two female red squirrels, though they have yet to produce offspring.

“We have this vision with our partners of being able to create another population that hopefully can serve as an additional backup on the mountain,” stated Tara Harris, the Phoenix Zoo’s director of conservation and science. “The risk of wildfire continues to be quite high for these squirrels, and so having that extra population is really important for their ongoing existence.”

The successful reintroduction of red squirrels into areas of Mount Graham once inhabited by them remains a key objective, with hopes that future breeding seasons will yield new offspring. “We are still chasing that elusive thing, trying to get actual pups born here,” Harris added, demonstrating the commitment to preserving this unique species.