THE MIGRATIONS OF OTHER BIRDS 197 



that persisted for many years throughout the greater 

 part of the eastern United States from Wisconsin 

 to Florida. The birds were killed by thousands and 

 became reduced in numbers, since they rear but one 

 brood with a maximum of two young each season, 

 and were unable to withstand the excessive drain 

 upon their number by the constant shooting to 

 which they were subjected. On the Potomac River 

 above the city of Washington the scanty autumn 

 flight that remains passes regularly down-stream 

 toward the southeast, a direction that seems to be 

 held until the birds pass beyond the limits of the 

 Piedmont plateau and reach the level expanses of 

 the Coastal plain. A number of years ago, while 

 studying the birds in the plains region of central 

 Oklahoma in late May, I found nighthawks very 

 abundant. Most of those secured were of the form 

 known as Howell's nighthawk {Chordeiles m.howelli)^ 

 which bred locally, but among others I secured three 

 specimens of the western nighthawk {Chordeiles m. 

 henryi)y which nests in New Mexico, Arizona, north- 

 ern Chihuahua and Sonora. As the latter were at 

 a point farther east than ever previously recorded, 

 we can only suppose that they were in migration 

 and were following the course of the South Canadian 

 River through Oklahoma to its headwaters in the 

 mountains of New Mexico. One year in the Bighorn 

 Basin in Wyoming, I saw nighthawks arriving from 



