Habitat use and life history of the Mount Graham red squirrel

Abstract

I studied habitat use by 9 radio-collared Mt. Graham red squirrels (Tamiasciurus hudsonicus grahamensis) during the summers of 1988 and 1989 in the Pinaleno Mountains, Arizona. My 2 study areas represented an Engelmann spruce (Picea engelmannii)/corkbark fir (Abies lasiocarpa) association on High Peak and a Douglas-fir (Pseudotsuga menziesii) association on Merrill Peak. I trapped 9 squirrels in 33,400 trap hours, and calculated the seasonal home range for 4 animals, 2 in each study area. Hidden density was 0.54 and 0.2 middens/ha, respectively, but seasonal home range size (x = 3.62 ha) did not vary between habitats. Squirrel numbers decreased on both study areas between 1988 and 1989. I concluded that preference for habitat characteristics in midden areas explained lower densities in the mixed conifer vegetation. Squirrels fed mainly on cones and mushrooms, depending on season and availability. Mt. Graham red squirrels may breed twice/year.