194 LAND BIRDS 



Although it may never have been heard before by the 

 watcher, it may be instantly and instinctively recognized 

 as it floats out of the deep ravine or from the darkness 

 of tlie woods. 



420 a. CALIFORNIA EIGHTH AW K. — Chordeiles 



virginianus hesperis: 



(Cbmmon names : Bull Bat ; Mosquito Hawk ; Will-o'- 



the-Wisp.) 



Family : The Goatsuckers. 



Length: About 9.00. 



Adiblt Male : Upper parts black, mottled with gray and buflFy ; a white 



or buffy patch on the wing ; tail, except the middle feathers, banded 



with white near the tip ; throat white ; chest black ; belly barred 



black and white. 

 Adult Female : No white on tail ; otherwise like male. 

 Downy Young: Covered with thin yellowish brown down mottled with 



darker. 

 Toung : Markings less distinct than on adults. 

 Geographical Dintribution : In California, the Transition and Boreal 



zones of the northern end of the State, and south through the 



Sierra Nevada; recorded during migration through the western 



valleys; south in winter to the tropics. 

 California Breeding Mange : Wooded districts of northern part of the 



State. 

 Breeding Season: May 15 to June 15. 

 Nest : None ; eggs laid on the bare ground. 

 Sggs ; 2 ; vary from pale olive-buff to buffy and grayish white ; thickly 



mottled and dashed with varied tints of darker gray, olive, or even 



blackish, marbled, and clouded with lavender. Size 1.25 X 0.85. 



With the exception of the Texan nighthawk the sub- 

 species of nighthawks occurring in California resemble 

 each other so closely that it is impossible to distinguish 

 them without shooting, and their ranges overlap in such 

 a way as to make locality an uncertain guide. Tiierefore 

 only one form, Chordeiles virginianus hesperis, without 



