THE GENUS CHORDEILES SWAINSON — OBERHOLSEE. 33 



tion of the subspecies separately. It is more than possible that an 

 adequate series of specimens of the various races (for nothing else 

 will answer) would show some interesting differences in their mi- 

 gration. The migration routes, however, by which several of the 

 different races reach their common winter home in South America 

 are discernible in a general way from the data now available. Con- 

 cerning the migration of Chordeiles virginianus Tninor and Chordeiles 

 mrginicmus mcinus we know nothing at all. The two eastern forms, 

 Chordeiles mrginianus chapmani and Chordeiles virginianus vir- 

 ginianus, fly southward across the Gulf of Mexico to Yucatan 

 and through Central America to South America, or through the 

 West Indies and across the Caribbean Sea. The return journey is 

 apparently by the same route. The route of Chordeiles virginia/nus 

 sennetti is unknown; but all the other western races pass south 

 through Mexico and Central America and return the same way. A 

 possible but unproved variation of this may take some or all of the 

 birds from the easternmost part of the ranges of Chordeiles vir- 

 ginianus howelli, Chordeiles virginiaTvas aserriensis, and Chordeiles 

 virginianus hesperis across the western end of the Gulf of Mexico 

 to Yucatan, and thence through Central America. There is no 

 authentic record of any of these western races in the United States 

 east of Illinois, or anywhere in the West Indies. 



Habits. — Few birds bear such a misnomer as the nighthawk; for 

 it is not a hawk, or even nearly related to one, nor is it a night-flier, 

 except by moonlight, though it prefers the twilight and the declining 

 hours of the day, as well as cloudy weather. It lives mostly in the 

 open country, such as the plains and prairies, and is a common sight 

 along roadsides, fence-rows, railroad tracks, and the like. It 

 avoids the deep forest, though it often enters the outskirts of wood- 

 land. Its flight is strong, swift, and light, at times not a little sug- 

 gestive of the sparrow hawk {Cerchneis sparveria) or other of the 

 small falcons. It is much on the wing, and some of its aerial per- 

 formances are really wonderful. Its ordinary call on the wing is a 

 sharp one- or two-syllabled note something like " aeh-eek " or " peenk," 

 and remarkably characteristic. The well-known booming sound so 

 frequently heard is made by the quick passage of air between the 

 primaries as the bird is suddenly checked in rapidly descending 

 flight. Its food, which it obtains on the wing, consists probably all 

 of insects, such as moths, flies, beetles, grasshoppers, and crickets. 



This nighthawk lays its eggs on the ground on bare rocks, or 

 even on the flat roofs of houses in cities. No nest at all is con- 

 structed. The time of nesting is somewhat earlier in the southern 

 part of its range; but for the species as a whole, it lasts from late 

 April to early August, though there is apparently but one brood. 



