230 BULLETIN 17 9, UNITED STATES NATIONAL MUSEUM 



Plwrrvages. — There are two quite distinct color phases, said to be 

 independent of age or season, in the adult Hammond's flycatcher. 

 As described by Ridgway (1907), in the white-bellied phase the 

 pileum and hind neck are "dull deep brownish gray (nearly mouse 

 gray) , the back, scapulars, lesser wing-coverts, rump, and upper tail- 

 coverts similar, but de<;idedly more olive; * * * chest and sides 

 of breast pale gray, gradually fading on sides and flanks: rest of 

 under parts dull white, yellowish white, or very pale primrose yel- 

 low." The yellow-bellied phase he describes as similar, "but more 

 olivaceous (sometimes brownish olive) above, chest and sides of 

 breast olive or buffy olive, and abdomen, etc., primrose or sulphur 

 yellow." The two extremes are rather uncommon, most of the speci- 

 mens are more or less intermediate, and the color differences may be 

 seasonal. 



Mr. Ridgway (1907) says that the young are "essentially like 

 whitish-bellied adults, but color of upper parts grayish brown, rather 

 than olive, wing-bands light buffy, and marginal under wing-coverts 

 buffy." 



Dickey and van Rossem (1938) write: "Hammond's flycatcher 

 differs materially from the other visiting species of Empidonax in 

 that it molts before leaving the north. We have many specimens 

 from the United States showing all stages of the postjuvenal and 

 adult fall molt which begins in August and is ordinarily complete 

 by the latter part of September. In this species the juvenal rectrices 

 (but not the remiges) are replaced with the body plumage at the 

 postjuvenal molt. Another point of difference is that the spring 

 molt ordinarily is not extensive. Good series of migrating spring 

 specimens taken in various western states in April and May show 

 varying amounts of new body feathers, particularly on the foreparts 

 and back, but most of the plumage is that acquired at the molt of 

 the previous fall." 



The postnuptial molt evidently begins very early, for an adult 

 male, taken on June 30, by Mr. Swarth (1922) "shows the begin- 

 ning of the molt"; and an adult female, taken July 27, "had re- 

 newed a large part of its plumage." A young bird taken "August 

 10, shows the beginning of the molt into the first winter plumage." 

 On the other hand, the adult molt sometimes is much delayed, for 

 Mr. Swarth (1929) collected an adult female in Arizona, on October 

 3, that was "apparently just beginning the annual molt." 



Food. — Practically nothing seems to have been published on the 

 food of this flycatcher, which probably does not differ materially 

 from that of the other members of the genus. 



Behavior. — Hammond's flycatcher generally spends most of its time 

 among the higher branches of the trees in which it lives, at greater 



