Vo1 ' 192<? VH ] Wetmore, Birds of Lake Burford, N. Mex. 245 



towards him, barely sliding under his breast, and emerged at once only a 

 few feet away, or at times advanced toward him brushing against him and 

 then turning away. A second male that tried to approach was driven 

 away by quick rushes though the female paid no attention to him. She 

 continued her diving and finally at intervals the male began to dive with 

 her, both emerging at once. As the display continued he joined her under 

 the water more and more frequently and finally both remained below the 

 surface for over thirty seconds where copulation apparently took place. 

 When they emerged the female swam away for a short distance with the 

 male following her. Frequently during these displays the female gave a 

 peculiar rattling, purring call like kwuh-h-h-h-h while the males whistled 

 in a low tone. 



The female bluebills seemed very anxious when they happened to spy 

 my head in the rushes, and swam back and forth with heads erect and 

 crests raised giving their peculiar calls. The males were more stolid and 

 paid little attention beyond taking care to keep out of gun range. Several 

 pairs were found about certain favorable . places for nesting, and I was 

 certain for a time that they were going to breed, a supposition fostered by 

 the displays that I saw continually among them. Careful search how- 

 ever failed to show nests and when finally on June 17 and 18, I shot 

 females that were paired and apparently nesting in points of rushes, I 

 found that, though in normal physical condition, they had not deposited 

 eggs, and, as the sexual organs were not developed, would not have done 

 so this year. As this has been treated fully in the introductory portion 

 of this report it will not be discussed further here save to state that the 

 bluebill apparently should not be listed among the breeding birds of Lake 

 Burford at present, though it seems possible that occasionally pairs may 

 nest there. 



Some of the unmated drakes exhibited great regularity in habit. Two 

 in particular were found every morning resting near a certain clump of 

 grass on one sandy point. All of the males observed were in full plumage. 



18. Erismatura jamaicensis (Gmelin). Ruddy Duck. — This duck 

 was one of the most common at Lake Burford and it was estimated that 

 55 pairs were breeding at the lake. When I first arrived part of these 

 birds had selected the areas where they were to spend the summer and 

 were already mated. Others were found in little parties composed of 

 both sexes in places where the rushes were too thin in growth to afford 

 nesting cover, but by June 1, with the increase in growth of the rushes, 

 Ruddy Ducks were distributed around the lake and seemed to be settled 

 for the summer. From observations made here it would seem that part of 

 these birds at least paired and mated after reaching their breeding grounds. 

 Apparently in some areas there were more females than males. 



The curious display of the males was seen every day and was observed 

 to the best possible advantage, as frequently birds displayed within 30 

 feet of me. They seemed to keep up the curious performance constantly 



