AUDUBON'S WARBLER 149 



Fall Migration. — In August the mountain breeding birds begin 

 to descend to lower altitudes and during September reappear on the 

 plains. The earliest migrants move south of the breeding range in 

 the last week of September and enter Mexico soon after the first of 

 October. The northern part of the range in Montana is deserted about 

 the 10th of October. 



The Bird and its Haunts. — Audubon's Warbler is the Myrtle 

 Warbler of the west. It is the same hardy, active bird with a similar 

 characteristic tchip and conspicuously yellow-patched rump. 



In Colorado, Keyser 5 says "this species inhabits all the upper 

 mountain valleys and on the steep slopes of the western as well as on 

 the eastern side of the Divide, I had the Audubon Warblers often at 

 my elbow. In summer they make their homes at an altitude of seven 

 to eleven thousand feet and are partial to pine timber ; indeed, I think 

 I never found them elsewhere save occasionally among the quaking 

 asps."' 



Walter Fisher writes that in California "in winter, Audubon's 

 Warblers invade the warmer valleys of the western, and are particu- 

 larly abundant in the southern part of the state, where they are perhaps 

 more in evidence than any other birds. They take possession of 

 orchards, arroyos, open plains, and even hot hillsides among chamiso 

 and yuccas, and ply their fly-catching trade with great singleness of 

 purpose. They burst from sycamore tops and dash after minute 

 insects, hover, and zigzag as skillfully as any Flycatcher. During these 

 very frequent sallies the yellow rump-patch is more or less visible 

 and serves as a convenient mark for identification. The white mark- 

 ings of wings and tail are even more conspicuous and useful for this 

 purpose. 



"During the breeding season auduboni retires to the higher moun- 

 tains and lives among firs and pines of the Canadian zone. The breast 

 now acquires two conspicuous black patches which contrast beautifully 

 with the yellow throat. The favorite hunting grounds of this Warbler 

 are among firs, pines, and incense cedars, or occasionally in willow 

 copses. The male is of a particularly musical disposition, providing a 

 rather monotonous flow of notes to which the ear is soon likely to 

 become insensible. Wherever Calaveras and Audubon Warblers are 

 abundant silence is banished from the mountains." (Fisher, MS.) 



Song. — The call-note of this species resembles the characteristic 

 tchip of its eastern representative, the Myrtle Warbler. 



Bowles* describes the song as "a short though pleasing little 

 warble, surprisingly feeble for so large a bird, and in no way equal 

 to that of its smaller relative the Yellow Warbler (D. astiva)." 



