The Mount Graham red squirrel (Tamiascurus hudsonicus grahamensis) is an isolated subspecies found only in the coniferous forests on the Pinaleno Mountains of southeastern Arizona. This limited distribution, combined with a small population and loss of habitat, has made the Mount Graham red squirrel vulnerable to extinction. In response to concerns about the precarious status of the Mount Graham red squirrel, the U.S. Fish and Wildlife Service listed it as an endangered species in June 1987.

Every spring and fall, biologists and volunteers from the Arizona Game and Fish Department, USDA Forest Service, U.S. Fish and Wildlife Service, and University of Arizona survey the red squirrel population. "We actually visit randomly chosen middens, or cone scale piles," explains Tim Snow, a biologist with the Tucson Office of the Arizona Game and Fish Department. "We look for recent activity such as new cone scales, fresh digging, and stored cones." Because red squirrels defend territories around these middens, biologists can estimate the population size from the percentage of middens showing recent activity.

Since 1991, inter-agency cooperators have conducted semi-annual surveys using this methodology, once each in the spring and fall. Mount Graham red squirrel population estimates have ranged from a low of 223 individuals in 1993 to a high of 562 individuals in 1999.

In light of this summer’s Nuttall Complex wildfires, biologists are concerned with additional loss of habitat for the squirrels. While the Fall 2004 survey indicates that the red squirrel population appears similar to the Spring 2004 estimate, it is too early to tell the total impact the Nuttall Complex wildfires might have had on the squirrels or the squirrel habitat.