274 BULLETIN 2 03, UNITED STATES NATIONAL MUSEUM 



as an addition to our fauna, and resulting in its reduction to sub- 

 specific rank. It is known to breed in the Huacliuca Mountains and 

 in the high Sierras of northwestern Mexico, ranging south to Guate- 

 mala. Swarth (1904) says of the status of the black- fronted warbler 

 in Arizona : 



This, the only form of auduboni that breeds in the Huachucas, occurs during 

 the summer months, though in rather limited numbers, in the higher pine 

 regions from 8500 feet upwards. On one occasion, April 5, 1903, I secured a 

 male nigrifrons from a flock of auduboni feeding in some live-oaks near the 

 mouth of one of the canyons at an altitude of about 4500 feet, but this is the 

 only time that I have seen it below the altitude given above; and it is also 

 exceptional in the early date of its arrival. No more were seen until the second 

 week in May, which seems nearer the usual time of arrival, for in 1902, the 

 first was seen on May 9th. * * * Several specimens were taken inter- 

 mediate in their characteristics between auduboni and nigrifrons ; some, of the 

 size of the latter, though in color but little darker than auduboni, while some 

 show every gradation of color between the two extremes. 



The black-fronted warbler averages somewhat larger than the 

 Audubon's. 



Nesting. — Before this warbler was known to be the breeding form 

 in Arizona, O. W. Howard (1899) reported on two nests found in the 

 Huachuca Mountains in 1898, and said that he had found "several 

 nests" of Audubon's warblers' in 1897 and 1898, all in these mountains. 

 These were all, doubtless, nests of the black-fronted warbler. One of 

 these was in a red fir tree about 15 feet up, and the other "was placed 

 in the lower branches of a sugar-pine about fifty feet from the ground, 

 and twelve feet out from the trunk of the tree. * * * Xhe nests 

 are very loosely constructed, being composed almost entirely of loose 

 straws with a few feathers and hair for a lining." One of Howard's 

 nests of this warbler, with four eggs, is in the Thayer collection in 

 Cambridge. It was found in the same mountains, at an elevation of 

 about 9,000 feet, saddled on the limb of a red spruce tree 35 feet above 

 ground and well concealed in the foliage. It is rather a bulky nest 

 made of shredded weed steins, fine strips of inner bark, fine rootlets 

 and various other plant fibers, mixed with feathers of the Arizona jay, 

 three long wing feathers of small birds and two small owl feathers; 

 it is lined with fine fibers, horse and cattle hair, and jay feathers. 

 Externally it measures about 3^/2 inches in diameter and 2^ in 

 height ; the inside diameter is about 2 inches and the cup is about 1% 

 inches deep. 



James Rooney has sent me the data for a set of four eggs 

 of the black-fronted warbler, taken by Clyde L. Field in the Santa 

 Catalina Mountains in Arizona, June 2, 1938. The nest, placed 15 

 feet above ground at the end of a pine limb, was made of twigs and was 

 lined with deer hair and a few feathers. A nest with four eggs, in the 



