632 U.S. NATIONAL MUSEUM BULLETIN 23 7 takt 2 



PIPILO ABERTI Baird 



Abert's Towhee* 



PLATE 36 



Contributed by William R. Dawson 



Habits 



The Abert's towhee comprises two subspecies, the ecology and the 

 behavior of which appear similar, and both forms are treated in this 

 accomit. They are abmidant residents in the vicinity of water 

 comi-ses, either permanent or intermittent, in parts of the deserts of 

 southwestern United States, and they actively penetrate the thickest 

 parts of the riparian vegetation with which they are characteristically 

 associated (E. Coues, 1866; C. B. R. Kennerly, 1859; W. Brewster, 

 1882a; W. W. Price, 1899; and John Davis, 1951). However, they 

 will exploit edge vegetation, and I was successful in trapping birds of 

 the subspecies P. a. dumeticolus at the junction between riparian 

 growth and what A. H. Miller (1951c) has termed "desert scrub" 

 vegetation. 



The plant associates of the two forms of the Abert's towhee are 

 generally similar. In New Mexico and Arizona, P. a. aberti has been 

 recorded most frequently in mesquite (Prosopis sp.) (H. W. Henshaw, 

 1875; F. Stevens, 1878; W. Brewster, 1882a; H. K. Coale, 1894; 

 G, F. Breninger, 1901; and H. S. Swarth, 1905a) and to a lesser 

 extent m cottonwoods (Populus fremontii) and willow (Salix sp.). 

 According to Davis (1951), the late A. J. van Rossem and L. H. 

 Miller collected them in arrowweed (Pluchea sericea) along the Bill 

 Williams River in western Arizona. They have also been observed 

 in Arizona about farms, citrus groves, and urban areas (F. M. Dille, 

 1935). The increased irrigation of desert lands in this state un- 

 doubtedly is increasing the amount of habitat suitable for Abert's 

 towhees. 



Birds of the subspecies P. a. dumeticolus have been most frequently 

 recorded in willow, mesquite, and arrowweed growth (W. W. Price, 

 1899; N. HoUister, 1908; van Rossem, 1911; G. Bancroft, 1922; and 

 W. R. Dawson, 1954), but J. Grinnell (1914b) concludes that they 

 are most commonly associated along the Colorado River with quail 

 brush (Atriplex lentiformis) and mesquite. In the Imperial Valley 

 of California I have observed them occurring frequently in a reed 

 {Phragmites communis), and somewhat less commonly in a species of 



*The following subspecies are discussed in this section: Pipilo aberti aberti 

 Baird and P. a. dumeticolus van Rossem. 



