34 The Wilson Bulletin — Xo. 103 



The nests were made of sycamore down without hning-. One 

 of the eggs is somewhat larger than the other, which is often 

 the case with sets of humming birds' eggs, and is usually 

 explained on the theory that the smaller egg will hatcli into 

 a male bird and the larger one into a female. 



Sometime ago I had the good fortune to find a nest of the 

 Ruby-throated Hummingbird on an apple tree branch near 

 my home at Willoughby. The nest contained two fresh eggs.. 

 While looking around I noticed a second nest a fcC^- feet 

 away, and upon examining it found that it was a last year's 

 one. Both nests had probably been made by the same pair 

 of birds, for aside from the discoloration and weathering of 

 the old nest, the two were identical in size, shape and gen- 

 eral appearance. This, coupled with the fact that they were 

 located within a few feet of each other, makes it almost cer- 

 tain that they were built by the same pair of birds. 



These are interesting examples of the wonderful instinct 

 which guides even the tiniest of birds over thousands of miles 

 of territory to their favorite summer nesting haunts. In the 

 case of the Black-chinned Hummingbird, however, it is quite 

 possible that the builders of the double nest, owing to the 

 mild climate of Southern California, had never strayed very 

 far away from the place it was found. 



A SECOND BIRD SURVEY AT WASHINGTON, D. C. 



BY HARRY C. OBERHOLSER. 



Our first comprehensive bird census ^ near W^ashington, 

 D. C, was such a success that we decided to repeat it in the 

 spring of 1917. On this second occasion twenty-two orni- 

 thologists took part, and the seventeen parties into wdiich they 

 separated covered pretty thoroughly the various kinds- of 

 country within twenty miles of the city. The date selected 

 was May 11, 1917, one day earlier in the month than in 1913 ; 

 and the choice proved to be a fortunate one, since an unex- 



^The Wilson Bulletin, XXIX (No. 98), March, 1917, pp. 18-29. 



