1920 J Wetmore, Birds of Lake Burford, N. Mex. 403 



The original male was mated on June 2 and the pair of Cowbirds re- 

 mained constantly nearby for ten days or more. On June 5 and 6 a second 

 female appeared and fed with the others. The male was seen running 

 at them with his bill pointing straight in the air and then pausing to sing 

 and display. The second female disappeared at once while the pair re- 

 mained together until June 13. After this the male was seen alone. He 

 continued to sing during the remaining time that I was there but ceased 

 displaying almost entirely. If observations made here are a proper cri- 

 terion the breeding season for the Cowbird is very short. 



60. Xanthocephalus xanthocephalus (Bonaparte). Yellow- 

 headed Blackbird. — Next to the Eared Grebe the Yellow-headed Black- 

 bird was the most abundant breeding bird at Lake Burford and the small 

 lakes nearby. It was estimated that in all 210 pairs were nesting here. 

 The adult males were settled in large part on their breeding grounds on 

 my arrival, though many of them were not yet mated. Each selected a 

 stand in the tules at the border of the lake, and, unless away feeding, 

 was certain to be found in the immediate vicinity constantly from that 

 time on. The birds were always tame but certain individuals whose 

 domain I passed almost daily on foot or in a boat soon became fearless 

 and I was able to recognize and look for these in certain spots constantly. 

 At this season the male seems fully conscious of his handsome coloring 

 and in his displays makes every effort to attract attention. In the most 

 common display the male started towards the female from a distance of 

 30 or 40 feet with a loud rattling of his wings as a preliminary. The head 

 was bent down, the feet lowered and the tail dropped while he flew slowly 

 toward his mate. The wings were brought down with a slow swinging 

 motion and were not closed at all so that the white markings on the coverts 

 were fully displayed, the whole performance being reminiscent of a similar 

 wing display of the Mocking-bird. In flying from one perch to another 

 males often dangled their feet, frequently breaking through small clumps 

 of dead tules with considerable racket. Or they clambered stiffly along, 

 hobbling over masses of bent-over rushes, with heads bent down, tails 

 drooping and back humped, appearing like veritable clowns. 



The song of these Yellowheads was subject to much variation, but 

 ordinarily resembled the syllables Klee Klee Klee Ko-Kow-w-w, the last 

 low and much drawn out. Their colonies were always noisy, and strange 

 cat-calls, drawn out wailing notes, and chattering protests came to my 

 ears constantly from birds in the rushes below camp as I worked on notes 

 or specimens. The ordinary call note of the males was a liquid cluck, 

 somewhat unlike the call of any other blackbird, while the call of the 

 female was more Redwing-like. 



Some of the birds had nests on my arrival and by May 2M nest-building 

 was going on everywhere. This task was performed entirely by the females 

 who worked at it nervously and energetically, using wet or damp materials 

 and molding them rapidly into shape. One brood of young had left the 



