PAuk 



28 Fry, Seasonal Decline in Bird Song. LJan. 



A STUDY OF THE SEASONAL DECLINE OF BIRD SONG. 



BY HENRY J. FRY. 



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This study of the decline of l)ird song was made at the 1914 

 Summer School of the Biological Laboratories at Cold Spring 

 Harbor, Long Island, while taking the course offered there in orni- 

 thology. Observations were begun July 1, and the last were made 

 August 10, hence the period studied comprises forty-one days. 



All work on the problem was confined to a limited area, not 

 more than three quarters of a mile square, centering about the 

 end of Cold Spring Harbor, which is an inlet from Long Island 

 Sound. TLe region contains an unusual diversity of bird habitats, 

 including open salt water, tidal marshes and sandy beaches, fresh 

 water lakes, streams and small swamps, road-ways dotted with 

 farm houses, orchards and open fields, scrubby pastures and dense 

 woods. The altitude ranges from sea level, along the edge of the 

 water to an elevation of from two to three hundred feet on the 

 hills immediately surrounding the inlet. 



There is nothing unusual about this vicinity that would effect 

 the decline of song in any abnormal way. Perhaps the presence 

 of so much water, surrounded by abrupt hills renders the atmos- 

 phere somewhat more humid than usual, but the average summer 

 temperature is about the same as is found at that latitude inland. 



Systematic observations were regularly taken many times each 

 day. Every morning from 6.00 to 7.30 was spent in the study of 

 song, as was the time from 10.00 to 11.30, and alternate aftertioons 

 were given to the same work. A large part of the other hours of 

 the days was spent in the open, and always with pencil and note- 

 book in hand, recording song data. The central parts of the area 

 were studied a little more closely than the rest, but all the remoter 

 sections were visited at least three or four times each week, espe- 

 cially when they harbored birds not found elsewhere in the locality. 



Three mornings a week, the half hour between 7.00 and 7.30 

 was devoted in a peculiar way to one of three especially favorable 



