610 U.S. NATIONAL MUSEUM BULLETIN 23 7 part 2 



of these feathers are worn away, the white feather bases are exposed. In examples 

 of extreme wear the throat may appear white, because only the feather bases 

 remain. The coloration of the crissum is also strikingly affected by wear, for the 

 intensity of the coloration of this area is determined largely by the thickness of 

 mass of the under tail coverts. As these become worn the color of the crissum 

 becomes paler, owing to the thinning of the feather mass. 



Food. — Brown towhees forage on the ground for seeds and insects. 

 Occasionally they pursue large flying insects, but in the main they 

 depend on the small ground surface forms. F. E. L. Beal (1910) made 

 a study of stomach contents of these birds and found weed seeds — 51 

 percent — to be their most important food, followed by grain — 28 

 percent. Insects were the principal animal food — 14 percent — and 

 fruit — 4.4 percent — probably windfalls, taken occasionally. 



To obtain its food the brown towhee does not scratch as frequently 

 or as violently as does the rufous-sided towhee. Birds are seen 

 occasionally feeding on new grass shoots and drinking the dew col- 

 lected on them in the morning. They respond well to feeding stations 

 baited with various commercial bird seeds and bread crumbs, oat 

 groats being particularly favored. The young, as in most other 

 fringillids, are fed entirely on insect material, largely moth and 

 butterfly larvae. 



Behavior. — A behavior pattern often mentioned in the literature 

 is the brown towhee's so-called ''shadow-boxing," a fighting response 

 aroused when its reflection in a shiny surface suggests the presence 

 of another towhee in its territory. D. P. Dickey (1916) first described 

 this action for senicula as follows: "Perching on the sill, the bird 

 would eye his reflection, and then set systematically to work to kill 

 the supposed rival, with all the ire and intolerance of a rutting moose." 

 Keflections from window panes near feeding stations frequently 

 stimulate these attacks, and hub caps often receive the same attention 

 in the Berkeley area from both towhees and robins. W. E. Bitter 

 and S. Benson (1934) describe and discuss the meaning of this phe- 

 nomenon in terms of breeding activity and territorial behavior: 



The Towhee, standing on the ledge, would face the window and assume a 

 threatening attitude by lowering its head, fluffing out its feathers, and drooping 

 its wings. It would then leap up at the window, striking it with its feet, or 

 with the feet and the beak at the height of about ten inches. It would then fall 

 back and immediately leap up to strike again. Sometimes it varied the pro- 

 cedure by continuing up the pane, clawing at its image as it rose. 



* * * 



After May 1 the bird fought the window every day until July 4. Its last 

 visit for the summer was July 14, but it appeared again on September 23 and 

 fought occasionally for some weeks. The amount of fighting was never constant 

 during this period. Beginning April 28 the bird increased its fighting activity 

 imtil May 16. During this period it confined its efi'orts to the wmdows of our 

 rooms. By May 20 the attacks had fallen off a great deal and the bird had 

 expanded the zone of its operations to include the west-facing windows of the 



