The Migration of North American Sparrows 



THIRTEENTH PAPER 

 Compiled by Professor W. W. Cooke, Chiefly from Data in the Biological Survey 



With Drawings by Louis Agassiz Foertes 

 (See frontispiece) 



EVENING GROSBEAK 



The Evening Grosbeak has been separated into two forms. The western, 

 montana, breeds in the mountains from southern British Columbia and 

 northwestern Montana south to southern Arizona. During the interim between 

 the breeding seasons, these birds wander over much of the district from the 

 eastern foothills of the Rockies to the Pacific Ocean, but their movements are 

 so irregular that no average dates can be calculated. On the plains near 

 Denver, Colorado, they remained, in the spring of 1909, until May 24. After 

 breeding in the mountains, the earliest returned to the plains August 8. 



The other form of the Evening Grosbeak, vespertina, breeds in the Rocky 

 Mountains north of the United States, and is strongly migratory. But instead 

 of moving in approximately north and south lines, as is the case with most 

 birds, these Evening Grosbeaks migrate east and southeast in the fall, and 

 return west and northwest in the spring. The following table will give an idea 

 of the usual time of migration in the district in which the birds occur nearly 

 every winter. 



FALL MIGRATION 



PLACE 



Manitoba. 

 Minnesota 



Iowa 



Wisconsin. 

 Michigan. 

 Ontario. . . 



Average date of 

 fall arrival 



October 31 

 October 21 

 November 18 

 November 1 1 

 November 22 

 December 18 



Earliest date of 

 fall arrival 



October 26, 1901 

 October 11, 1880 

 November 2, 1898 

 October 10, 1903 

 October 21, 1909 

 December 5, 1906 



How irregular are the movements of the Evening Grosbeak can be judged 

 from its record at Chicago, 111. Dates of arrival: December 20, 1883; Decem- 



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