346 AXIMAL LIFE IX THE YO SEMITE 



Pacific Nighthawk. Chordeiles virginianus hesperis Grinnell 



Field characters. — Body size that of robin, but with much longer and more slender 

 wings; these when closed reach to end of tail or beyond. Similar to poor-will in many 

 respects. Chin and narrow band across middle of longer wing feathers, white; rest of 

 plumage barred or spotted with brown, gray, black, and white, in mixed pattern, giving 

 a neutral effect. Flight erratic, with many quick turnings. Voice: A one- or two- 

 syllabled note, zee-nt, or pee' -ark. 



Occurrence. — Summer visitant in small numbers to higher open country (Canadian 

 and Hudsonian zones on west slope, and Transition ea,«t of Sierran ciest). Observed in 

 1915 at Merced Lake August 25; Vogelsang Lake August 30; Tuolumne Meadows 

 July 5, 7, and 27; and at Williams Butte Septemljer 15; Paoha Island, Mono Lake, July 

 3, 1916; and on ridge 3 miles east of Coulterville, August 9 and 11, 1920. Reported in 

 Yosemite Valley June 28 and 29 and August 24, 1920. Active chiefly in evening and 

 morning; forages high in the air. Spends most of daytime resting lengthwise on large 

 horizontal limbs of trees. 



The Pacific Nighthawk is a summer visitant to the higher parts of the 

 Yosemite region. It begins its forays for insects at sundown or soon after 

 and continues its activity well into or through the hours of complete 

 darkness. In July, when the young probably have hatched out, the adult 

 birds forage in the daytime as well. For instance 2 or more were seen 

 abroad foraging over Tuolumne Meadows about 9 :30 on the morning of 

 July 27, 1915. 



The nighthawk is provided with a wide gaping mouth which enables 

 it to capture flying insects with facility; the long and narrow wings and 

 tail enable the bird to fly rapidly and to turn quickly when in pursuit 

 of moths, flying ants, or other insects which frequent the upper air. 



Prom time to time a Pacific Nighthawk while flying at a considerable 

 height will suddenly drop into an abruptly doAvnward swing with wings 

 held above the back in V-shape. As the bird checks its flight and darts 

 upward, a rushing noise is heard, resembling the syllable 'Avhoof. ' Whether 

 or not this is produced by the wings we do not know. 



At Williams Butte on September 15, 1915, 5 nighthawks were seen in 

 flight high overheard about 4 :15 p.m. ; these were probably in migration, 

 as none was seen after that date in places where they were observed earlier 

 in the season. 



Six or more of these birds, actively engaged in foraging, were noted 

 near the crest of the ridge 3 miles east of Coulterville on August 9 and 11, 

 1920. None was seen in this locality, which is at the lower margin of 

 the Transition Zone, in June of 1915, so those seen later in the season were 

 probably 'vagrants.' 



In Yosemite Valley a pair of these birds flew low over the river on the 

 .stormy evenings of June 28 and 29, 1920; and during a hea\y storm on 

 August 24, 1920, a lone bird coursed for two hours up and down over the 

 Merced River (C. W. Michael, MS). 



