224 BULLETIN 17 6, UNITED STATES NATIONAL MUSEUM 



or fly away when I approached to pick it up. When I arrived on 

 the roof wall it gave a series of calls, which seems to be a sign of 

 recognition. The bird placed before me in a natural sitting pose 

 measured 187 millimeters from the tip of the bill to the tip of the 

 wings. Distance from level of the crown to the board on which it is 

 seated is 90 millimeters. Tip of tail to front of toe in natural posi- 

 tion 150, and tip of folded wing to toe 165 millimeters. 



The bird at this age is very active and vivacious and captures all 

 its own food. It offers no difficulty for me to capture it for meas- 

 urements and poses perfectly for photographs. 



On Monday, August 15", there was a great flight and departure of 

 nighthawks, and after that date the nighthawk was seen no more. 

 Presumably it went southward on its migration. The bird was 52 

 days old, and I had an unexcelled opportunity to observe the bird 

 up to the time of the completion of its growth. 



The completed juvenal plumages of both sexes is similar to that 

 of the adult female except that the throat patch is not so well defined ; 

 in some it is replaced by blackish and buffy bars. The barring of 

 the underparts is more extensive and the coloration in general is 

 paler than that of the adults. There are whitish tips on all the 

 primaries. 



The postnatal molt has already been described in detail under the 

 account of the young. There is a partial molt that does not include 

 the wings and tail in September. There is a partial or complete 

 prenuptial molt in spring when the young attain the plumage of 

 the adult. The adults have a complete postnuptial molt before they 

 return for their nesting activities the following year. I have not 

 been able to ascertain the time of the postnuptial molt. 



Albinistic phases of plumage, in which there is an absence of 

 dark pigment, may appear in any species of birds. W. A. Strother 

 (1886) reports a perfect albino taken at Lynchburg, Va. 



Food. — The nighthawk is insectivorous in its eating habits. Since 

 the major part of the insects it destroys are destructive to useful 

 vegetation or are otherwise adverse to human welfare, the night- 

 hawk ranks high in the list of birds beneficial to man. 



The nighthawk captures the insects chiefly during its flight. The 

 birds sweep up in their capacious mouths all types of insects from 

 the large moths and beetles to the tiniest of flies and mosquitoes. 

 Some of the stomachs examined have contained no less than 50 

 different species of insects, and some of the smaller insects are at 

 times represented by thousands of individuals. 



One of the most conspicuous elements of the food is flying ants. 

 In the examination of 87 nighthawk stomachs, the United States 

 Biological Survey reports that ants comprised nearly one-fourth of 



