54 ANIMAL LIFE IN THE YOSEMITE 



The method used in collecting bats may be illustrated by giving the 

 circumstances under which a Little California Bat was taken at El Portal 

 on November 20, 1914. Well before twilight the collector had taken up a 

 station in the open where a clear view was obtainable. The first bat seen 

 abroad on that evening was a Hoary Bat, noted at 5 :10 p.m. Up to 5 :35 

 four more bats, all small, the size of the Little California Bat, were seen. 

 Twice, as these small ones crossed low places in the horizon line, and so 

 could be seen against the sky, loads of dust-shot were fired at them. In 

 the case of the one bat obtained, the collector fired his guii in the general 

 direction taken by the bat after it passed the clearing; it just happened 

 that the animal had continued its flight in a straight line. A soft thump 

 told that the bat had been dropped. The collector lined it up with a 

 distant object, dragged the toe of his shoe to leave a location mark, walked 

 forward, and then at the judged distance began working over the ground 

 in concentric circles, picking up every dark object — until his fingers 

 encountered the soft body of the bat. 



All our bats are strictly insectivorous. The food of the Little California 

 Bat, so far as we know, consists solely of flying insects. Because of their 

 crepuscular habits bats are able to feed upon an entirely different category 

 of insects than are the day foraging insectivores, the swallows, swifts, fly- 

 catchers, etc. Their forage comprises to a considerable extent beetles and 

 moths, and since the larvae of these are often destructive forest pests, the 

 bats are thus of material service to the trees. In truth the bats constitute 

 one big arm of the "night patrol." 



A rather unique departure in forage range was noted in the case of 

 a Little California Bat at Pleasant Valley early in December, 1915. The 

 house in which a member of our party was quartered there had on one 

 side a large shed-room in which were unusually large numbers of house 

 flies. At dusk, when the flies were buzzing about slowly and seeking warm 

 resting places in which to spend the night, a Little California Bat would 

 come forth from its daytime retreat and course back and forth in the 

 room, where it found easy forage in the logy flies. All too soon, to the 

 naturalist's way of thinking, the bat had captured enough flies for its 

 evening meal and retired. 



During the late summer and autumn months bats, as a rule, become 

 very fat. In all probability this storage of excess nutriment is an adjust- 

 ment to provide against winter and early spring when forage is scarce 

 or when the weather is such that bats cannot venture out to feed. When 

 collecting specimens during October or November, it is a rather common 

 experience to find bats so fat that when they are shot the 'oil' begins at 

 once to ooze out of the shot holes and, by the time the collector has retrieved 

 his specimen, the fur of the bat will be matted with the grease. During 



