Zoo Wetmore, Birds of Lake Burford, N. Mex. [April 



continuing these antics until dark. Another immature bird was taken on 

 June 15. 



5. Hydrochelidon nigra surinamensis (Gmelin). American Black 

 Tern. — -Three were seen on June 6, apparently in migration. 



6. Pelecanus erythrorhynchos Gmelin. American White Pelican, 

 A few were found in migration. Two were observed on May 26, two on 

 May 27, and four on May 28, all resting on shore. It is possible that 

 these birds were on their way north into the Salt Lake Valley. There is 

 no food for them at Lake Burford save the abundant water-dogs (Arnby- 

 stoma sp.). 



7. Mergus americanus Cassin. American Merganser. — Found 

 at Lake Burford during migration. A small flock was seen on May 27, 

 and fourteen pairs were observed on May 30. These remained in open 

 water and were very wild. On June 3, four males and two females were 

 found. They flew and left the lake immediately when I came in sight 

 though a long distance away. On June 10, twenty-five males all in full 

 plumage came in, flying in a great V, circled over the lake, and then passed 

 on. An adult male was flushed from the shore on June 15. There are no 

 fish in the lake so that these birds must come here for water-dogs (Amby- 

 stoma sp.). 



8. Anas platyrhynchos Linnaeus. Mallard. — The Mallard was 

 one of the most common species of ducks breeding at Lake Burford and 

 I estimated that forty pairs were preparing to nest here this season. These 

 ducks shifted about from place to place more than any others on the lake, 

 and were seen flying morning and evening. Towards night they came in 

 to feed where openings in the rushes allowed them to reach the shore, 

 where they secured food that had been washed in by the waves. At day- 

 light nearly every morning I found a pair feeding in the spring hole where 

 we secured our water supply. About eight in the morning the birds came 

 out on little open beaches and remained until towards noon, preening, 

 sleeping and resting in the sun. 



Mallards are undemonstrative birds and, though they were under ob- 

 servation during much of the time that I was out, it was seldom that I saw 

 any sign of mating display among them. This species has a mating flight, 

 similar to that of the Gad wall, in which two males and one female rise in 

 the air together and fly along rather slowly with the female flying beside 

 first one and then the other of the males. In turn these swing in ahead of 

 her and setting their wings throw up their heads and display their back 

 and wing markings. During this performance the males call constantly 

 while the female quacks at intervals. The whole lacks the dash and speed 

 of the display of the Gadwall and the birds do not change direction 

 so frequently, pursuing a more even course. In another action the female 

 came out on shore and walked about in the short grass with head extended 

 quacking loudly, perhaps simulating a search for a nest site. Sometimes 

 the male accompanied her and sometimes he remained standing quietly 

 on shore. 



