The Mt. Graham red squirrel (Tamiasciurus fremonti grahamensis) is a subspecies that is only found on Mt. Graham in southeastern Arizona. It was actually thought to be extinct in the 1950s until it was rediscovered two decades later. On June 3, 1987, the Mt. Graham red squirrel was listed as endangered under the Endangered Species Act.

Recent analyses indicate that the Mt. Graham red squirrel belongs to a different species than the North American red squirrel that ranges across much of the United States and Canada. Instead, the Mt. Graham red squirrel appears to be a subspecies of Fremont’s squirrel – a species found in Arizona, New Mexico, Colorado and Utah. It is distinguished by a smaller body and narrower head, but maintains the brownish-red sides and white belly that characterize other squirrels in its species.

Mt. Graham red squirrels are most active during the day and spend their time foraging for seeds of coniferous trees; however their diet also consists of insects, mushrooms, bird eggs, nestlings and various other items. Males and females are highly territorial and will aggressively defend their midden (territory) from other squirrels. Like other members of its species, Mt. Graham red squirrels do not hibernate during the winter, but will only venture out during mid-day when it’s warmest.

The forest habitat of the Mt. Graham red squirrel has been impacted by wildfire and disease, reducing the available food resources and cover from predators. This has led to a reduction in the squirrels’ wild population. In addition, an introduced squirrel species (Abert’s squirrel) is now outcompeting Mt. Graham red squirrels for limited food resources.

threats

habitat loss/
degradation

invasive species

Climate change/
severe weather

How We Help

at the zoo

Since 2014, the Zoo has been working to develop a pilot breeding program for Mt. Graham red squirrels, in the hope of producing animals for release to the wild. We maintain a small population of squirrels at the Arthur L. and Elaine V. Johnson Conservation Center, in a temperature-regulated building. Our staff has developed husbandry guidelines for the species and has observed breeding behavior. As of yet, though, no kits have been produced.

In the wild, red squirrel females are typically receptive to males during a single day per year. We are working with our partners on research to understand when to best pair the squirrels for breeding. By gathering data on changes in squirrel behavior, hormones, anatomy, and cell biology, we aim to improve our chances of successful reproduction. This work has been generously supported by an Arizona Game and Fish Commission Heritage Fund grant.

conservation partners