344 ANIMAL LIFE IN TEE TO SEMITE 



Poor-wills are essentially birds of the night. Along with nighthawks 

 and bats they replace the swallows, swifts, flj^catchers, and other birds that 

 feed upon flying insects during the daytime. Soon after sundown of the 

 long summer days the notes of the poor-wall are to be heard coming from 

 the grease-wood or sagebrush-covered slopes of the hills, and a little later 

 the birds themselves begin to take wing low over the chaparral or grass- 

 lands in search of their food. 



Poor-wills are adapted in many ways for their night-time activities. 

 Their eyes are large, suggesting those of owls. The mouth is broad, 

 extending across the whole w^idtli of the head and, when open, forms, with 

 the row of outstanding bristles on either side, a gaping trap into which 

 flying insects can easily be scooped. Their plumage is soft, if anything 

 even more so than that of owls, and so their flight is noiseless, seemingly 

 a necessity in night-foraging birds in general. The wings of the poor-will 

 are relatively long but rounded in outline at their ends, like those of the 

 ground owl. The mottled color pattern of the plumage (pi. 43&) blends 

 well with almost any broken surface, such as gravelly ground, on wdiieh 

 the birds may chance to rest, and this may be helpful to them during the 

 daylight hours in making them less easily seen by their enemies when they 

 are resting or sleeping. Certainly the human observer finds difficulty 

 enough in detecting the presence of one of these birds on the ground so 

 long as it remains quiet. 



Poor-wills do not usualFy begin to forage until late dusk, being even 

 more nocturnal in this respect than nighthawks ; nor are they seen abroad 

 in the morning as late as are those birds. On the evening of May 20, 1915, 

 at Pleasant Valley, as one of our party was riding along the Baxter Road 

 which winds uphill through the greasewood (Adenostoma) , several Dusky 

 Poor-wills were seen along the margin of the chaparral. At the approach 

 of the horse the nearest bird would rise a few feet above the ground, fly 

 a short distance up the road, and then settle down close to the roadway, 

 only to start up again erratically when further disturbed. These birds 

 are active through at least the early hours of the night ; for on August 18, 

 1915, one was heard calling from near Cathedral Spires, in Yosemite 

 Valley, between 9 and 10 o'clock at night. 



As regards occurrence in the Yosemite Valley, this last record was 

 made in the season when poor-w'ills are known to range up the mountains 

 into the lower part of the Transition Zone, where they do not ordinarily 

 occur earlier in the year. We have the statement by Mr. W. 0. Emerson 

 (1893, p. 179), however, that the notes of a California Poor-will could 

 be heard "high up on the cliffs above the valley" between June 20 and 25, 

 1893. 



