THE CHIMNEY SWIFT. 183 



The average measurement of fifty-six eggs in the United States National 

 Museum collection is 20.03 by 13.22 millimetres, or 0.79 by 0.52 inch. The larg- 

 est egg of the series measures -21.34 by 13.72 millimetres, or 0.84 by 0.54 inch; 

 the smallest, 17.53 by 13.72 millimetres, or 0.69 by 0.54 inch. 



The type specimen, No. 24019 (PL 1, Fig. 25), from a set of four eggs, was 

 taken by Mr. J. C Pennock, near Kennett Square, Pennsylvania, on June 16, 

 1887, and represents about an average egg of this species. 



64. Chaetura vauxii (Townsend). 



VAUX'S SWIFT. 



Cypselus vauxii Townsend, Journal Academy N'atural Sciences, Phila., VIII, 1839, 148. 

 Chwtura vauxii De Kay, Zoology of New York, II, 1844, 36. 



(B 110, C 272, R .352, 406, U 424.) 



Geographical range: Western North America; chiefly west of the Sierra Nevada 

 and Cascade mountains; north in British Columbia to about latitude 52° and probably 

 farther; east to western Montana and southern Arizona; south to northern Lower Cali- 

 fornia, and in winter through Mexico to Honduras, Central America. 



Vaux's, or the "Oregon" Swift, a somewhat smaller and paler-colored bird 

 than the preceding, is principally confined to the Pacific Coast regions, and 

 appears to be much rarer and more sporadically distiibuted in the interior, east 

 of the Sierra Nevadas, and in the Cascade mountains of California, Oregon, 

 Washington, and British Columbia. The most northern record I have been 

 able to find is one by Mr. Samuel N. Rhoads, published in the "Proceedings 

 of the Academy of Natural Sciences of Philadelphia, 1893" (p. 44), where he 

 reports seeing this species near Lac la Hache, British Columbia, on July 1, 1892. 

 He also met with it at Goldstream, on Vancouver Island, on May 13. It reaches 

 the eastern limits of its range, as far as it at present known, in western Montana, 

 where Mr. C. P. Streator took a specimen at Silver, in Missoula County, on June 

 25, 1891. Mr. W. E. D. Scott met with it early in October, 1884, on the San 

 Pedi'o slope of the Santa Catalina Mountains, in southern Arizona, at an altitude 

 of from 3,000 to 4,000 feet.-^ These birds were probably migrating. Mr. F. 

 Stephens observed it daily, and secured a specimen at Olancha, California, on 

 the eastern slopes of the Sierra Nevadas, in the latter part of May, 1891. He 

 believes they were migrating.^ 



The limits of its breeding range are not well defined as yet. Mr. F. 

 Stephens considers it only a migrant in southern California. The only breeding- 

 records I have are both from Santa Cruz County, in this State, in about lati- 

 tude 37°, and it appears reasonable to suppose that it breeds from there north- 

 ward. But very few nests and eggs of Vaux's Swift have, as far as I am aware, 

 found their way into collections. It possibly breeds also in the more mouii- 



iThe Auk, Vol. Ill, 1886, p. 429. 



^Biids of the Death Valley Expedition, North American Fauna, No. 7, 1893, p. 55. 



