A Note on the Prothonotary Warbler. — In the many biographical 

 sketches of the Prothonotary Warbler, one finds considerable unanimity 

 concerning the succession of mating and nest building and the sex building 

 the nest. For instance, Loucks in his ' Life History of the Prothonotary 

 Warbler,'! states; "Soon after mating, the birds begin to build their 

 nest.. . .In the construction of the nest, the female bird works alone. I 

 have never yet seen a male really aiding in this task." The authors, 

 studying in localities where the bird is more or less abundant during the 

 breeding season, evidently made such notes from series of observations. 

 A single instance contrary to the above is, therefore, probably less import- 

 ant than it is interesting. The case in point is that of a male Prothonotary 

 Warbler which appeared at Ithaca in the spring of 1910. It was first seen 

 May 31 in some willows overhanging a back-water from Fall Creek, one 

 of the main tributaries of Cayuga Lake. It was singing at the time but 

 soon flew down to the water's edge. Here it seized a good sized straw and 

 thence carried it to a hole in a dead stub some five feet above the water. 

 The site was an abandoned Downy Woodpecker's nest, the opening of 

 which had, by some agent or other, been enlarged leaving its borders 

 jagged and rough. While the bird was under observation, it continued 

 flying to and from the hole carrying bits of grass, straw, bark and the like, 

 most of which was obtained at the water's edge. It sang very frequently, 

 often with nesting material in its bill, which was opened so widely during 

 the process that the material was sometimes lost. The nest was not 

 examined closely at this time for fear of disturbing the bird but from the 

 place of observation the nesting, material was seen projecting from the 

 hole. Nothing was seen of a female. Two days later the bird had ceased 

 carrying nesting material and was singing in the willows nearby. Upon 

 careful examination the nest was found to be quite complete but there 

 were no eggs nor was there yet any sign of a female. For eleven days this 

 male was seen or heard singing about the spot but no eggs ever appeared 

 in the nest and no female was ever discovered. He was never seen to 

 enter the nest after the third day of observation but, with one exception, 

 was found at all hours within fifty feet of the nesting site, usually singing. 

 On one occasion he was seen to drive away a Bluebird which alighted on 

 the stub. On June 12 he disappeared and did not return. 



From these observations it would seem that this male, very shortly after 

 arriving and before finding a mate, selected the nesting site and began 

 building the nest. Furthermore, after completing the nest he waited, 

 apparently for a female, at least nine days before deserting the site which 

 he had chosen. In localities where the species is more abundant and mating 

 is therefore assured, the necessity for the males building the nest may never 

 arise. But the fact that this male, when isolated, was able to select the 

 site and complete the nest in the absence of the female is quite significant. — 

 Arthub a. Allen, Cornell University, Ithaca, N. Y. 



' Loucks, W. E. Bulletin 4, Article 3, Illinois State Laboratory of Natural 

 History. 



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