16 Porter, Nesting Habits of Birds in the Spring of 1907. ff^J^ 



NESTING HABITS OF BIRDS AT STAMFORD, CON- 

 NECTICUT, AS AFFECTED BY THE COLD SPRING 



OF 1907. 



BY LOUIS H. PORTER. 



The spring of 1907 was abnormally cold and backward. The 

 prevailing temperature during the last week of May and the first 

 week of June was about the same as we usually expect the middle 

 of April. While vegetation was somewhat backward, the effect 

 on the nesting habits of our birds was even more pronounced and 

 interesting. 



During the migrating season I saw very few birds, less than a 

 tenth as many migrants as usual, but those that I did see were at 

 about the usual dates, and did not average later than normal. 

 During the nesting season, however, birds seemed more abundant 

 than usual, but their habits were materially altered. I did not 

 obtain sufficient data to justify any broad generalization, but from 

 my observations it seemed that most birds commenced nest building 

 at about the average calendar date, but that as a result of the cold 

 season the more delicate species took very much longer in their 

 nest building; when the nest was finally completed, the egg laying 

 period was also protracted, extending to two or three times its 

 usual period; and finally that after the set was completed, the 

 birds, in some cases at least, did not immediately commence sitting. 



If other observers noticed a similar condition, an interesting 

 question is raised as to the extent to which this protraction of the 

 breeding period was due to volition on the bird's part, or to the 

 physical effect of the cold weather upon the genital organs. 



My records show the following data in support of these conclu- 

 sions. 



Helminthophila pinus. This bird breeds abundantly at Stam- 

 ford, and is the most regular in its habits of any bird I know of. 

 My records prior to this year give the earliest breeding date, May 

 27, and the latest June 10 (young nearly ready to fiy) with an 

 average of May 29. All the sets I had taken May 30, or later, had 

 incubation well advanced. Other published records which I con- 

 sulted agree with this experience. Full sets can usually be found 



