60 proceedings: biological society 



PROCEEDINGS OF THE ACADEMY AND AFFILIATED 



SOCIETIES 



THE BIOLOGICAL SOCIETY OF WASHINGTON 



The 488th regular meeting was held at the Cosmos Club, November 

 18, 1911. Four new members were elected. The first communication 

 was an illustrated paper on a Study of distribution based upon the family 

 Pyramidellidae, by Paul Bartsch. 



The second communication was entitled The peculiar migration of the 

 Evening Grosbeak, by Wells W. Cooke. 



Most species of North American birds have migration routes that are 

 approximately north and south, while the migration route of the Even- 

 ing Grosbeak is nearly east and west. 



The species is rather common in the mountainous parts of western 

 North America from central Alberta to southern Mexico. It has been 

 divided into three farms : montana includes all the breeding birds of the 

 United States and southern British Columbia; mexicana, all the breed- 

 ing birds of Mexico; and vespertina, the remainder of the breeding birds 

 of Canada. 



The species was originally described from migrants taken in April, 1823, 

 at Sault Ste. Marie, Mich., but it was more than half a century later 

 before the first eggs were found. The first published description of the eggs 

 was by Bryant in 1887 of a set found May 10, 1886, in Yolo County, 

 Calif. A set of eggs had been taken two years earlier at Springerville, 

 Ariz., but an account of it was not published until 1888. Ten years 

 elapsed before the next set was taken in 1896 near Lake Tahoe, Calif. 

 There had been only three sets found, therefore, up to 1901, when Mr. 

 F. J. Birtwell found at Willis, N. M., five nests in one small colony. He 

 secured the eggs from two of the nests and lost his life by an accident in 

 climbing after the third. Only a few nests have been found in the last 

 ten years, so that there are scarcely a dozen sets of the eggs of the Even- 

 ing Grosbeak in existence at the present time. All of these eggs belong 

 to the subspecies montana; the eggs of the type species vespertina are still 

 unknown to science, although young have been found in the nest. 



The form montana is not migratory in the strict sense of the word. 

 It nests in the mountains and spreads out in winter time into the valleys 

 and the neighboring plains. The form vespertina, nesting entirely north 

 of the United States in the mountains of Alberta, is strongly migratory, 

 but instead of moving south in the fall, which would bring it into the 

 district occupied throughout the year by montana, it journeys eastward 

 and is a common winter visitant in Manitoba and Minnesota. Hence it 

 spreads less commonly to Iowa, Wisconsin, Michigan and western 

 Ontario. The species was scarcely known further east until the winter 

 of 1889-90, when a remarkable invasion of the Evening Grosbeak was 

 noted throughout much of the northeastern United States. So numer- 

 ous were they that more than a thousand were killed in the vicinity of 



