ABERT'S TOWHEE 635 



used to separate first-year birds from second-year or older birds. In fresh fall 

 plumage the primaries of the first-year ( = immature) birds are dull brown and the 

 margins of these feathers are finely erose because of wear. The primaries of 

 second-year and older (=adults) at this time are glossy and nearly black and 

 the margins of these feathers are entire. The rectrices of immature birds have 

 pointed tips * * * and show signs of wear. The rectrices of adults are obtuse at 

 the tip * * * and are glossy and unworn. Since rectrices are often replaced in 

 the postjuvenal molt, the amount of wear on the primaries offers the most reliable 

 criterion for judging age, * * * 



Juveniles are at once distinguished from immatures and adults by the extensive 

 streaking and spotting of the underparts and by the very soft and lacy texture of 

 the head and body plumage. 



Coues (1S66) considered the molt of the Abert's towhee to occur 

 from July well into October. Henshaw (1875) found aU of the six speci- 

 mens he obtained along the Gila River in mid-September to be molting. 

 I did not observe towhees in this condition in the Imperial Valley of 

 California until late August. 



The Abert's towhee has a grayish brown pileum and a slightly paler 

 and grayer dorsum. Its breast, sides, and flanks are pinkish gray. 

 The chin is black and the throat is grayish pink streaked with black. 

 The under tail coverts are dull cinnamon, and the primaries are dark 

 grayish brown with the rectrices blackish brown. P. a. aberti, 

 originally described by S. F. Baird (1852), differs from P. a. dumeticolus, 

 originally descnbed by van Rossem (1946a), in having a darker, 

 grayer pileum and dorsum, and grayer underparts with a pinkish 

 rather than a cinnamon tinge. The bill in both forms is horn colored 

 and contrasts strongly with the black face patch. Immatures and 

 adults show no consistent differences in coloration (Davis, 1951). 



Food. — No comprehensive study of the food habits of Abert's 

 towhees has been published, but presumably the general nature of 

 their diet approximates those of the brown and the spotted towhees 

 (P. fuscus and P. erythro'phtalmus) analyzed in CaUfornia by F. E. L. 

 Beal (1910) — animal material constituted 14 percent of the total food 

 taken by the former and 24 percent of that by the latter. I have 

 observed Abert's towhees foraging extensiv^ely around quail brush, 

 apparently obtaining the fallen seeds of this plant, and I have trapped 

 these birds successfully using millet seed as bait. Like most other 

 passerines, they will readily eat meal worms {Tenebrio larvae) in 

 captivity. Their utilization of insects in nature is suggested by 

 Stevens's (1878) and Stephens's (in Brewster, 1882a) observations of 

 their hunting in the bark of large trees like wrens or nuthatches. 



Behavior. — The wariness of Abert's towhees has impressed many 

 ornithologists, and Bendire (1890) rated them among the shyest birds 

 of his acquaintance. They are generally difficult to approach and to 

 observe, because of the denseness of the riparian growth which they 

 frequent much of the time. However, it is usually easy to detect 



