The Mount Graham red squirrel (''Tamiasciurus fremonti grahamensis'') is an endangered subspecies of the southwestern red squirrel (''Tamiasciurus fremonti'') native to the Pinaleño Mountains of

Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...

. It is smaller than most other subspecies of red squirrel, and also does not have the white-fringed tail that is common to the species. Its diet consists mainly of mixed seeds, conifer cones and air-dried

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

. It exhibits similar behavior to other squirrels in its species.

Description

Physical

The Mount Graham red squirrel is a generally tiny squirrel weighing on average around and measuring about in length. The subspecies also has a tail. Unlike most other squirrels in its species, the squirrels do not have a white-fringed tail. Both females and males share similar markings and features and are typically grayish brown in color with rusty yellow or orange markings on their backside. During the winter season, the squirrels' ears are tufted with fur, and during the summer a black lateral line is observed on the squirrel. The

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

of the subspecies is rounded and its teeth are low-crowned.

Behavior

Mount Graham red squirrels behave in a manner similar to most other subspecies of American red squirrel. They are diurnal and do not hibernate during the winter months, but instead carry out activities in the mid-day sun. Mount Graham squirrels usually eat a diet of mixed seeds, conifer cones and air-dried fungi.

Habitat

Historically, the Mount Graham red squirrel inhabited about of spruce-fir, mixed-conifer and

ecotone An ecotone is a transitional area between two plant communities, where these meet and integrate. Examples include areas between grassland and forest, estuaries and lagoon, freshwater and sea water etc. An ecotone may be narrow or wide, and it ma ...

zone habitats that were generally at higher elevations throughout the Pinaleño Mountains. Recent data shows that it occurs more frequently at the

zone than the other habitats. When choosing a potential nesting site, the squirrels typically pick a cool, moist area with an abundance of food sources.

Drought A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, ...

forest fires A forest fire A wildfire, forest fire, or a bushfire is an unplanned and uncontrolled fire in an area of combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identified as a bushfire ( in Au ...

, and insect infestation have been responsible for a decrease of the squirrel in the spruce-fir habitat.

Conservation

The Mount Graham subspecies was believed to be extinct in the 1950s, but was "rediscovered" in the 1970s. After its rediscovery, it was suggested for threatened or

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...

species status under the

Endangered Species Act The Endangered Species Act of 1973 (ESA; 16 U.S.C. § 1531 et seq.) is the primary law in the United States for protecting and conserving imperiled species. Designed to protect critically imperiled species from extinction as a "consequence of e ...

in 1982. On May 21, 1986, the subspecies was officially recommended to become an endangered species, and effective June 3, 1987, was listed as endangered. The Mount Graham International Observatory was controversial when it was built in the squirrel's habitat; the observatory has been required to monitor the community near the observatory to determine if its construction is having any negative effects on the population.

Habitat loss Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

is also occurring at high levels for a variety of natural and

anthropogenic Anthropogenic ("human" + "generating") is an adjective that may refer to: * Anthropogeny, the study of the origins of humanity Anthropogenic may also refer to things that have been generated by humans, as follows: * Human impact on the enviro ...

reasons. In 1988, the U.S. Fish and Wildlife Service designated most of this area as a refuge, and access to the area is granted only with a special permit. A lightning strike on June 7, 2017, started a wildfire that could have led to the extinction of this subspecies. In September 2019, the U.S. Fish and Wildlife Service agreed to consider if the squirrel needed further protection. They were petitioned under a procedure of the Endangered Species Act by a group that contends it is necessary to remove the observatory and other private structures.

References

External links

USFWS PageMount Graham Red Squirrel Research Program at School of Natural Resources and the Environment at University of Arizona
{{Authority control Tamiasciurus Endemic fauna of Arizona Endemic rodents of the United States Pinaleño Mountains Graham County, Arizona Mammals described in 1894 Endangered fauna of the United States ESA endangered species Species that are or were threatened by habitat loss