2i6 THE MIGRATIONS OF BIRDS 



summer in herons and a few others, which is followed 

 by a retreat south with the coming of cold weather. 

 The various races of the large-billed sparrow {Pas- 

 serculus rostratus) follow an unusual course, which 

 is an exception to the general rule. For many years 

 they were recorded along the southwestern coast of 

 California and in Lower California, but their breed- 

 ing place was unknown. Recently it has been dis- 

 covered that the species as a whole nests from the 

 mouth of the Colorado River south to the western 

 coast of Lower California, and that in autumn, from 

 this restricted breeding range, it migrates in part 

 south along the coast of Lower California and Mex- 

 ico, and in part north along the coast of California^ 

 as it is common on the coastal marshes of Los 

 Angeles County and comes north regularly as far 

 as Santa Barbara. A large number of individuals 

 thus pass the winter a considerable distance north 

 of their breeding ground. No other perching bird 

 in the North American avifauna is known to have 

 this habit. 



Heermann's gull of the western coast has a some- 

 what similar migration, as it breeds on islands in the 

 Gulf of California and on the western coast of Ja- 

 lisco, and then migrates north as far as Vancouver 

 Island in British Columbia. 



