As part of a conservation program for the endangered Mount Graham red squirrel, the Arizona Game and Fish Department, U.S. Forest Service and U.S. Fish and Wildlife Service conducted an annual squirrel survey and estimated approximately 214 animals in the Pinaleño Mountains in southeastern Arizona.
The latest survey count is in line with the population numbers found in 2010, but represents a decrease of 26 squirrels from the 2011 estimate.
Small mammal species like the Mount Graham red squirrel typically have cyclical populations that depend on the conifer cone crop, their primary food resource. Biologists continue to explore new ways to conserve the species, including habitat improvements, squirrel research and consideration of a pilot captive breeding program.
The red squirrel survey is conducted annually in the fall by visiting a random sample of known middens (areas where red squirrels store or cache their cones).
The Mount Graham red squirrel population spiked to around 550 animals in the late 1990s, but typically ranges between 200 and 300 individuals. Habitat losses caused by fire and insect infestations and poor cone crops caused by drought are considered primary factors in the species’ recent trends.
“Squirrel numbers commonly fluctuate due to available habitat and food resources, so it is not unusual to see a small drop in the population numbers,” says Tim Snow, nongame specialist for the Arizona Game and Fish Department. “The lack of winter and summer rains over the last few years is suspected to have impacted the squirrels’ cone crop.”
Mount Graham red squirrels live only in the upper elevation conifer forests of the Pinaleño Mountains and feed primarily on conifer seeds. Females produce two to seven young annually. The species was added to the endangered species list in 1987.
The multi-agency Mount Graham Red Squirrel Recovery Team, including the Coronado National Forest, Game and Fish, U.S. Fish and Wildlife Service, University of Arizona, Native American tribes and others, oversees conservation of the species.
Image courtesy Arizona Game and Fish Department