1913 BIRDS OF THE FRESNO DISTRICT 57 



(luring the last half of March. By the end of the fir'^t week in April nighthawks 

 have usually hecome quite numerous, but it is not until the first half of May is 

 gone that they begin nesting in any considerable numbers. During August these 

 birds are very conspicuous, and the author has sometimes observed literally hun 

 dreds of them fl}'ing about a certain alfalfa grown swale near Clovis. Many of 

 these, no doubt, were immature birds, which remain with us until their first fall 

 migration. This usually occurs in early September. 1 have never observed this 

 species later than September t8 ( 1905) when a lone nighthawk was seen flying 

 over a vineyard near Clovis. 



Preparing a nest in which to deposit her two eggs is not a difficult task for 

 the female nighthawk, as, in every case that has come under my notice, the eggs 

 rested on the bare, dry earth with not a vestige of nesting material either under 

 or around them. It is a hopeless task to look for these eggs unless the parent 

 bird is flushed from them, and even when the angry birds have revealed almost 

 their exact location it sometimes requires no little careful hunting to detect the 

 eggs, on account of their striking resemblance to small clods. When disturbed on 

 her eggs the female usually makes a purring noise and flies but a short distance 

 when she again alights; if forced into the air she is soon joined by her mate, who 

 is often more demonstrative than the female and darts around near the intruder, 

 frequently giving a peculiar clucking call. 



As the great majority of our nighthawks nest in the vineyards, they are, no 

 doubt, frequently disturbed, and possibly this may account for their eggs being 

 found in late July, as recorded beyond. 



Below is given a list of the few nests observed by the author, nearly all be- 

 ing found by flushing a bird at a time when nighthawks were farthest from his 

 thoughts. 



May 15, 1906; two eggs; one abnormal in shape and infertile, the other con- 

 taining small embryo. Eggs at base of vine in vineyard. Ground very dry and 

 hard. Both birds unusually bold. 



July 2, 1906; two eggs; good-sized embryos. Eggs on soft ground at base 

 of a sunflower growing in a field of melons. Bird flushed. 



May 27, 1907 ; female flushed from two slightly incubated eggs that rested 

 in a very slight natural depression about one foot from the stump of a large vine. 

 These' eggs were in the shade, as all others have been ; it seems possible that the 

 incubating birds move their eggs around in order to be protected from the direct 

 rays of the sun. 



May 26, 191 1 ; two considerably incubated eggs on bare ground in vineyard. 

 Bird flushed at close range. 



July 21, 191 1 ; two eggs; incubation advanced. Bird flushed from bare 

 ground, between two vines in vineyard. 



Mr. J. D. Clark has sent me nighthawk eggs from near Letcher that were 

 found on small knolls in a pasture where there was little or no protection. 



As the nighthawk seems to have few enemies it will doubtless continue to be 

 an abundant summer visitant to this part of the San Joaquin Valley for years to 

 come ; and it should be a welcome visitor for it feeds on a class of insects that are, 

 to a great extent, ignored by other birds. When night begins to spread her veil 

 of darkness over the fields and vinevards a host of winged creatures come out 



