52 ANIMAL LIFE IX THE YO SEMITE 



Often this is the first species of bat to appear abroad in the evening, 

 though it is sometimes preceded by the Merriam Pipistrelle. At El Portal 

 on November 22, 1914, a Little California Bat was out at 5:10 p.m. At 

 Pleasant Valley, late in May (24th to 27th) of the year following, the 

 species was still among the first to appear, though at that season indi- 

 viduals did not come out until much later, 7 :25 to 7 :45 p.m. The strength 

 of the light was about the same at the two hours mentioned. The bats 

 evidently stayed in their retreats for some 2^^ hours longer in summer 

 than in winter. 



Little California Bats are to be found in the Yosemite region throughout 

 the year. Our records include nine of the twelve months and are so 

 distributed as to indicate continued residence by the species, at lea.st below 

 the 3500-foot contour. But whether the same individuals are present at 

 all seasons or whether, like the fox sparrows, the summer population moves 

 out and is replaced by another contingent which comes in from the north 

 and winters here, is a point still to be determined. In Yosemite Valley 

 bats believed to be of this species have been seen out as late as October 27. 

 At Pleasant Valley the species was recorded abroad definitely on Decem- 

 ber 5 (1915), and a dead individual was picked up on Smith Creek, 6 

 miles east of Coultcrville, on February 7, 1916. 



These bats find shelter in a variety of situations. In Yosemite Valley, 

 at 6 P.M. on August 10, 1915, a Little California Bat, after circling over 

 and drinking at a pool near the foot of Yosemite Falls, was seen to take 

 refuge in a crevice between boulders. On May 30, 1911, the smoke of a 

 fire built in a rocky cavern near the foot of Illilouette Falls routed out a 

 Little California Bat which had been hanging in a crevice overhead. A 

 number of these bats have been found on or in the walls of old wooden 

 buildings and a few have been discovered in crevices in pine trees. Under 

 original conditions as well as at the present time the species was probably 

 very adaptable in its choice of shelter. 



Bats are active only at twilight and after dark. Their daytime retreats 

 are often difficult of access or unknown and their capture is neither easy 

 nor sure. It is therefore more difficult to gather information concerning 

 them than concerning birds and most other mammals. For these reasons 

 the body of accurate knowledge accumulated by naturalists is much less 

 complete for bats than it is for many other forms of animal life, despite 

 the fact that, in many cases, a disproportionately large amount of time 

 has been devoted to their study. While our parties were engaged in field 

 work in the Yosemite region one or more members would be out almost 

 every evening attempting to shoot the bats seen coursing over hikes or 

 ponds, or across openings in the forest; and every clue concerning the 

 location of "roosts" was eagerly followed up. Yet our total collection of 



