Tamiasciurus hudsonicus grahamensis (J. A. Allen 1894)

The Mount Graham red squirrel (Tamiasciurus fremonti grahamensis) is an endangered subspecies of the southwestern red squirrel (Tamiasciurus fremonti)^[3] native to the Pinaleño Mountains of Arizona. 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. 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 8 ounces (230 g) and measuring about 8 inches (20 cm) in length.^[1] The subspecies also has a 6 inches (15 cm) tail.^[1] Unlike most other squirrels in its species, the squirrels do not have a white-fringed tail.^[1] 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.^[1] During the winter season, the squirrels ears are tufted with fur, and during the summer a black lateral line is observed on the squirrel.^[1][4] The skull of the subspecies is rounded and its teeth are low-crowned.^[4]

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.^[5] Mount Graham squirrels usually eat a diet of mixed seeds, conifer cones and air-dried fungi.^[6]

Habitat

Historically, the Mount Graham red squirrel inhabited about 11,750 acres (47.6 km²) of spruce-fir, mixed-conifer and ecotone zone habitats that were generally at higher elevations throughout the Pinaleño Mountains.^[6] Recent data shows that it occurs more frequently at the ecotone zone than the other habitats.^[6] When choosing a potential nesting site, the squirrels typically pick a cool, moist area with an abundance of food sources.^[6] Drought, forest fires, and insect infestation have been responsible for a decrease of the squirrel in the spruce-fir habitat.^[6]

Conservation

The Mount Graham subspecies was believed to be extinct in the 1950s, but was "rediscovered" in the 1970s.^[7] After its rediscovery, it was suggested for threatened or endangered species status under the Endangered Species Act in 1982.^[8] On May 21, 1986, the subspecies was officially recommended to become an endangered species, and on June 3, 1987, was officially listed as endangered.^[1][9] 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.^[7] Habitat loss is also occurring at high levels for a variety of natural and anthropogenic reasons.^[7] 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.^[7] A lightning strike on June 7, 2017, started a wildfire that could have led to the extinction of this subspecies.^[10]

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.^[11]

References

格莱汉姆山红松鼠，它属于松鼠亚目。现存仅300只左右，瀕臨滅絕。^[2]比其他松鼠类小，主要食用种子或针叶以及干燥真菌类。^[3]

习性

格莱汉姆山红松鼠，原来是生存美国亚利桑那州的山脉 。比其他松鼠类小，无白色尾巴。它的食物来源包括主要的种子、针叶、干燥真菌等。与其它松鼠极其相似。体重约230克左右，身长15厘米-20厘米左右。^[3]

重新发现

灭绝是在20世纪50年代，却在20世纪70年代的重新发现。1987年6月3日，被加入濒危物种。^[3]

参考资料