EASTERN BROWN-HEADED COWBIRD 427 



mating. They did not drive others from the food in the domain, 

 carried on no boundary line defense, but tolerated both sexes in 

 social contacts, feeding and flying together. I believe these birds 

 displayed vestigial territory behavior in intimidating others so as to 

 keep the domain for their own use in pair formation and mating, 

 and this behavior perhaps may function to some extent in keeping 

 other females from utilizing host nests within the domain of the 

 dominant female. 



"All evidence indicated that pairing and monogamous mating 

 generally prevail. Although both sexes on many occasions through- 

 out the breeding season associate in trios or larger groups, there was no 

 indication of polygamous or promiscuous mating." 



Courtship. — Friedmann (1929) noted three types of courtship 

 display, the terrestrial, the aerial and the arboreal displays. He 

 describes the first of these as follows: "The male would run alongside 

 of the female, and when slightly ahead of her would turn a little so as 

 to be placed somewhat diagonally to her, and would then ruffle the 

 feathers of his neck and the interscapular region. Then he would 

 bow or bend down his head a little and emit his squeaky, shrill note — 

 pseeee. The wings and tail are not involved in the terrestrial mode 

 of courting." Charles W. Townsend sent Friedmann the following 

 note on this performance: "April 9, 1922 — Three males and one 

 female busily engaged in eating in a field. Every now and then a 

 male would look up, puff up feathers, spread wings and tail and fall on 

 head. This is evidently the bowing, as in trees, where he does not 

 fall. Since this time I have seen the performance several times and 

 it always impressed me as a falling and being stopped by his head and 

 breast striking the ground. * * * It seems to me that the tree act 

 is a low bowing, while on the ground act is an actual fall, for the bird 

 suddenly lets himself go and brings up against the earth, a comical 

 procedure." 



Of the aerial display, Friedmann (1929) says: "The display of the 

 males in mid-air consisted of ruffling out the feathers of the neck, 

 interscapulars and throat, bending down the head, and arching the 

 wings more than in usual flight, and giving their squeaky song. 

 During the instants when the wings were arched in display the flight 

 seemed unsteady, a sort of half-hearted attempt at a glide during an 

 unaccustomedly long interval between wing beats." Two males 

 that he watched following a female "seemed to display and sing in 

 unison. The two males and the female kept on flying back and forth, 

 at an altitude of about two hundred feet, from 7:15 a. m., when they 

 were first seen, until about 8:30 a. m., when they were last seen, with- 

 out resting or alighting even for a second," 



