BLACK-TAILED GNATCATCHER 379 



feathered, their coloration is similar to that of the adult female, but 

 until the fall molt takes place they can be distinguished by the greater 

 amount of white on their tails. The general molt occurs only in the 

 fall, so that by summer the white edgings of the outer tail feathers of 

 the adults have by abrasion become much reduced or altogether 

 lacking. 



As observed by the present writer, the black cap of the male, a 

 seasonal character, is assumed in February, black patches appearing 

 on the crown and quickly spreading over the entire top of the head. 

 The reverse change in the fall takes place much more slowly, in the 

 form of a gradual obscuring aDd replacing of the glossy black by gray. 

 The first signs of gray could be detected about the middle of July, or 

 early in August in another year, and it required approximately a 

 month and a half for all traces of darker color, with the exception of a 

 permanent blackish streak above the eye, to disappear. The change 

 appeared to be complete before the new tail feathers were entirely 

 grown out. Concerning variations in the molt, H. S. Swarth (1902) 

 writes: 



I have taken many specimens between August and March showing no black on 

 the head, with the exception of the almost invisible black streak over the eye, 

 which is, I believe, always present in the male; and others during March and 

 April undergoing moult over the entire crown; so I was the more surprised on 

 taking on December 13, 1901, a male bird with the black cap nearly complete, 

 though not quite as extensive as in most spring specimens, and with the black 

 feathers tipped with the blue-gray of the rest of the upper parts, so that the black 

 was not apparent unless the feathers were ruffled. It would have taken but 

 little abrasion of the tips of these feathers to have rendered this bird indistinguish- 

 able from specimens taken during April and May. On December 19 I secured 

 another, almost a counterpart of the one described above. * * * 



The time for the spring moult seems to be extremely variable; I have specimens 

 taken at the end of February, with no trace of the black crown, and not yet 

 commencing to moult; while on January 20, 1902 I took one with many pin feathers 

 on the head and the black cap nearly complete. Usually, I think that the change 

 of plumage is not finished before the first week in April. No part of the bird but 

 the crown seems to be affected by the moult. 



I am unable to confirm a further statement by Mr. Swarth that the 

 winter plumage is tinged with brown. However, one female which 

 was watched during the nesting season was notable for the decidedly 

 brown tone of the back and wings, in contrast to the clear gray of the 

 male. I have noticed no brownish tendencies in any other individuals 

 at any time of year. 



Food.— Prof. F. E. L. Beal (1907) reports as follows on the food 

 of the gnatcatchers: 



Only 30 stomachs of P. c. obscura and the same number of P. calif ornica have 

 been examined, and their contents were so similar that they may be treated as 

 from a single species. 



