254 BULLETIN 56, UNITED STATES NATIONAL MUSEUM. 



The young are brought forth during the period from May to 

 August, inclusive, the time varying somewhat with the altitude. 

 The nests are placed in the branches of the pines, frequently resting 

 upon an old jay's nest. They are usually constructed of terminal 

 pine boughs, lined with dry grass. It is probable that two litters 

 are sometimes raised in a season. The number of young was deter- 

 mined in three instances. A female, taken on the summit of the 

 Mogollon Mountains May 27, 1887, contained three young, and three 

 and four fetuses, respectively, were found in the uteri of two speci- 

 mens taken at Pine Tanks, at the lower border of the pine forest, 

 30 miles north of Fort Verde, on June 19 of the same year. At 

 Bakers Butte young were running in the trees by the middle of the 

 following month. 



This species is active throughout the year, but inclined to lie quiet 

 during heavy storms and severely cold winter weather. Its food con- 

 sists mainly of the seeds of the pine, acorns of the deciduous oaks, 

 groundnuts (Aralia), and green vegetation in summer. I once saw 

 one running in the trail ahead of me, carrying a very large, white 

 mushroom in its mouth. I halted to watch it, when it ascended a 

 pine tree and began eating the mushroom voraciously. By the latter 

 part of July the pine cones have nearly attained their full size and 

 the seeds are sufficiently mature for. the squirrels to begin feeding 

 upon them. Under every prolific pine visited by this squirrel green 

 chips from the cones may then be seen lying, together with the cen- 

 tral cores. The hunter can often locate the squirrels by. observing 

 the chips as they come whirling down from the trees and by the 

 sound made in tearing the cones in pieces. I have never seen the 

 Abert squirrel engaged in hoarding up food, and suppose that, it 

 leaves the morrow to care for itself. The stores preserved by the 

 provident carpentero, or Mexican woodpecker (Melanerpes formi- 

 civorous), are appropriated by it whenever found, and beyond doubt 

 these caches relieve it at times from extremities of want when the 

 ground is deeply covered with snow and the pine cones mostly fallen 

 or divested of their seeds. The Mormon settlers of Pine Creek in- 

 formed me that the Abert squirrel commits some depredations on 

 their crops of Indian corn, eating both green and ripe ears, but that 

 it does much less damage than the Eocky Mountain line-tailed 

 ground squirrel {Citellus grammurus). 



I suspect that the Abert squirrel sometimes interferes with the 

 nests of birds. On July 21, 1886, when camping near Flagstaff, 

 Arizona, a pair of western robins had established themselves in a 

 young pine tree close by, the nest being placed about 20 feet above 

 the ground. One morning there was a great outcry from the birds, 

 and I found them furiously assaulting a large squirrel, which they 

 drove away, whereupon I completed their victory by shooting it. 



