640 BULLETIN 2 03, UNITED STATES NATIONAL MUSEUM 



half of the state, and a common migrant in the mountain valleys and 

 at the edge of the prairie region near the mountains. A rare migrant 

 in the eastern part of the state. Breeds in the Canadian zone, in 

 willow thickets along the mountain streams or bordering mountain 

 lakes. West of the divide the Pileolated Warbler breeds in arbor- 

 vitae forests." 



It probably breeds in eastern Oregon, but Gabrielson and Jewett 

 (1940) say that "the first actual Oregon nest remains to be discovered." 

 According to Prof. Cooke (1904), "in Colorado it breeds commonly 

 at timber line, ranging from 12,000 down to 6,000 feet." 



The northern pileolated warbler is much like the eastern Wilson's 

 warbler, but it is somewhat larger on the average and its coloration 

 is brighter, the upper parts being more yellowish olive-green and the 

 yellow of the under parts brighter. It is, however, not so brightly 

 colored as the golden pileolated warbler that breeds in California. 



Spring. — From its winter home in Mexico and Central America 

 this subspecies makes a long flight to northern Alaska, and over a 

 wide range, from the Pacific coast to the eastern foothills of the 

 Eocky Mountains. It is a later migrant in California than the local 

 breeding form. Mrs. Amelia S. Allen tells me that the golden pileo- 

 lated warblers generally arrive on their breeding grounds in March 

 or very early in April, sometimes as early as March 11. She says in 

 her notes: "About the middle of May, after the breeding birds are 

 busy nesting, migrating birds pass through on the way north." 



Harold S. Gilbert writes to me: "On June 11, 1933, Mr. Everett 

 Darr, of the Mazamas, found 200 frozen pileolated warblers scattered 

 over the snow and ice at about 10,000 feet elevation, in the crater 

 of Mt. St. Helens, Wash. He brought some of these birds to my office 

 for identification. Apparently, during migration they had been 

 swept up in a storm and frozen." 



Nesting. — Herbert Brandt (1943) found five nests of this warbler in 

 Alaska, of which he says : 



The nest of the Pileolated Warbler in the Hooper Bay area is found only in 

 the vicinity of the willow and alder thickets that decorate the lower mountain 

 slopes. Out in the cleared defiles and under the matted dead grass that never 

 again rises from its supine position after being beaten down by winter's pres- 

 sure, this little bird builds its home. The nest may be sunken flush with the 

 mossy sod, or it may be built in the center of a large grass tuft, in which case 

 it may be elevated a few inches above the surrounding floor. However, so 

 closely hidden is it that considerable searcli is required to discover the dainty 

 abode. 



The nest is made entirely of short grass straws that are not interwoven, and 

 the structure is therefore so fragile that it will scarcely retain its form when 

 removed. The lining may be entirely of fine, thread-like grass shreds, or there 

 may be admixed therewith considerable coarse dog hair. If the latter is used, 

 each hair is laid in separately, and none of the wool-like tufts of the dog's under 



