THE LEAST FLYCATCHER. 315 



to take fully a week or more to complete the nest. The female performs the 

 duties of incubation almost exclusively, and this, as nearly as I have been able 

 to determine, occupies about twelve days. The return migration to their winter 

 home in Central America usually begins about the middle of September, none 

 remaining in our Southern States. 



The eggs vary from three to six in number, usually four, and one is depos- 

 ited daily. They are short and rounded ovate in shape; the shell is strong and 

 thick for its size, and without lustre. The ground color is pale creamy white, 

 and they are unspotted. The Cowbird imposes its eggs on several of our 

 smaller Flycatchers, including occasionally the one now under consideration. 



The average measurement of eighty-five eggs in the United States National 

 Museum collection is 16.14 by 12.70 millimetres, or about 0.64 by 0.50 inch. 

 The largest egg of the series measures 17.02 by 12.95 millimetres, or 0.67 by 

 0.51 inch; the smallest, 15.24 by 11.43 millimetres, or 0.60 by 0.45 inch. 



The type specimen, No. 24993 (PL 2, Fig. 31), from a set of four eggs, 

 from the Ralph collection, was taken by Dr. William L. Ralph, near Holland 

 Patent, New York, on June 3, 1882, and represents an average egg of this 

 species. 



116. Empidonax hammondi (Xantus). 



HAMMOND'S FLYCATCHER. 



Tyrannnla hammondi Xantus, Proceedings Academy Natural Sciences, Philadelphia, May, 



1S58, 117. 

 Empidonax hammondi Baikd, Birds of North America, 185S, 199. 

 (B 145, C 260, E 327, C 390, U 468.) 



Geographical range: Western North America; east to the eastern slopes of the 

 Rocky Mountains and adjacent ranges; north through British Columbia to Alaska, and to 

 Little Slave Lake, southern Athabasca, latitude 55° 20' (as far as known), and probably 

 still farther in this direction; south iu winter to Lower California and southern Mexico. 



The breeding range of Hammond's Flycatcher, which appears to be the 

 western representative of Empidonax minimus, is still very indifferently defined. 

 It is only known positively to breed in Colorado, California, Washington, British 

 Columbia, and southern Athabasca, in the Dominion of Canada, but its summer 

 range undoubtedly also extends through the higher mountain regions of New 

 Mexico, Arizona, Utah, Wyoming, Montana, Nevada, Oregon, and Idaho. 

 Throughout our Western States it has thus far been met with chiefly during its 

 migrations, and comparatively few thoroughly identified nests and eggs have 

 yet been taken. I have seen this species in May near Fort Klamath and Camp 

 Harney, Oregon, but I am almost sure none remained in the vicinity to breed. 

 The birds which stay with us during the summer appear to retire mostly to 

 the higher mountain valleys, at altitudes of from 5,000 to 10,000 feet. This 

 accounts for the few nests and eggs which have thus far been discovered within 

 our borders; and the fact that it is also a very shy and silent bird partly accounts 

 for its rarity as well. 



