1914] GrinneU: ilammals and Birds of the Colorado Valley 147 



Myiarchus cinerascens cinerascens (Lawrence) 

 Ash-throated Flycatcher 



Our capture of an example of this flycatcher as earl.y as February 

 19 in a willow tract on the California side five miles below Needles, 

 would appear to indicate that the species winters in the region. This 

 idea is further borne out by Cooper's observation (1870, p. 317) that 

 he encountered an individual at Fort Mohave January 15. On March 

 8 in the willow groves in Chemehuevis Valley we saw three ash-throated 

 flycatchers; on March 9, two. Thenceforth the species was noted 

 regularly. It was common above Bill Williams River, affecting a 

 tract of mesquites as well as the willows; also at Riverside Mountain 

 and above Blythe. At Ehrenberg, besides scattered individuals, sev- 

 eral pairs were encountered IMarch 27 in the saguaro belt back on the 

 mesa ; in each case the birds had obvious claims on some old wood- 

 pecker hole in a huge cactus trunk. Opposite Cibola and ten miles 

 below Cibola individuals were seen to enter rotted-out cavities in iron- 

 woods. 



The species was less common at our stations twenty miles north 

 of and eight miles east of Picacho. But in the saguaro belt on both 

 sides of the river and within five miles above the Laguna Dam the 

 ash-throated flycatcher was one of the characteristic breeding birds. 

 The woodpecker holes in the giant cactuses are pre-eminently suited 

 to these birds as nesting sites. A nest on the Arizona side was 

 chopped out April 21 and found to contain one fresh egg. The nest 

 cavity was five feet above the ground, and was bedded with a mass 

 of burro hair and duck feathers. Another nest, found on the Cali- 

 fornia side, April 23, M'as twelve feet above the ground in a cavity 

 fourteen inches deep ; composed of a closely packed mass of rabbit 

 fur ; there were four eggs in which incubation was well along. 



Ash-throated flycatchers were further observed, though more spar- 

 ingly, at our stations at Potholes, four miles south of Potholes, five 

 miles northeast of Yuma, and at Pilot Knob. 



A specimen (no. 4293) is in the Museum taken by J. G. Cooper 

 at Fort Mohave April 13, 1861. 



Our series of twenty-five specimens (nos. 12836-12860) was secured 

 as a residt of an unsuccessful attempt to detect the presence of some 

 one of the Mexican forms which come regularly into southern Arizona. 

 While it is probable that this series includes transient individuals, it 

 is not possible to pick them out. and the majority are. for certain. 



