394 Wetmore, Birds of Lake Bur-ford, N. Mex. LJuiy 



female in full plumage, with the ova showing some development. It 

 seems probable that these birds were on their way to the mouth of Bear 

 River at the northern end of Great Salt Lake, Utah, as that is the only 

 interior breeding colony in the region. These late migrants would reach 

 there in time to form the breeding units that came in to the colonies as 

 late as the middle of June. 



22. Nycticorax nycticorax naevius (Boddaert). Black-crowned 

 Night Heron. — Fifteen pairs of these Herons were found at Lake Bur- 

 ford and at the time of my departure were preparing to breed in the rushes 

 at the upper end of the Laguna de la Puerta. It is possible that there 

 may have been another colony established later at the main lake. A 

 few were present when I first arrived at Lake Burford, but they did not 

 become common until May 29. Birds were flushed from the rushes during 

 my work along the lake shore or were seen occasionally, five or six to- 

 gether, enjoying the sun on open beaches. In evening they flew back 

 and forth in front of the cabin to convenient points from which to watch 

 for the water-dogs {Ambystoma) that with frogs formed the only food- 

 supply available here. On one occasion while I was sitting in a blind in 

 the rushes a Night Heron flew by and spying a dead Axolotl floating in the 

 lake alighted on the water (where it was six feet deep) to seize the water- 

 dog in its bill. After resting thus for a minute the bird rose easily from 

 the surface and flew off with its prey. It was somewhat of a surprise to 

 find the Night Herons acting as scavengers, but they kept the dead Axo- 

 lotls well cleaned up until the last part of my stay, for though I saw many 

 floating on the surface of the water, comparatively few were found at 

 any time washed up along the shore. 



The birds often were found during the day time watching for water- 

 dogs in the shadow of rocky points. Until the first of June I thought 

 that at times they were rather hard-pressed for food for, as the water 

 was cold, the Ambystoma seemed still inactive, and dead ones had not 

 appeared on the surface in any numbers. 



Night Herons in second year plumage were seen at intervals. 



23. Rallus virginianus Linnaeus. Virginia Rail. — One was heard 

 calling on May 25 and one was flushed in a narrow band of tules on the 

 lake shore on May 27. Others were heard calling on June 7, 10, 11 and 12, 

 so that it is possible that one pair at least nested here. 



24. Fulica americana Gmelin. American Coot. — Next to the Eared 

 Grebe and Yellow-headed Blackbird the Coot was the most abundant 

 breeding species here and it was estimated that 150 pairs in all were nest- 

 ing at the lake. Many were in pairs on the date of my arrival, but until 

 June 5 small flocks of unmated birds remained feeding in the open bays 

 or rested in little bands on open beaches. Toward the latter part of 

 this period these flocks at short intervals presented a scene of great anima- 

 tion as the birds displayed and fought savagely with one another. A 

 little later on the companies broke up entirely. Each male selected an 



