Productivity and Populations 281 



Table 10 



PRODUCnVTTY RaTES AND CHANGES IN BREEDING POPULATIONS— 



Connecticut Hill Area— 1930-1941 ^ 



Percentage Increase of Percentage Change in 



September Population Breeding Population 



Year over That in April ' from Previous Spring 



1930 

 1931 

 1932 

 1933 

 1934 

 1935 

 1936 

 1937 

 1938 

 1939 

 1940 

 1941 



^ Figures taken from Edminster ( 1938) and from data in N. Y. S. Cons. Dept. Ann. 

 Reports, 1930-41. 



' Also referred to as the "recovery rate." 



ries through to the changes in the subsequent breeding population. 

 Productivity increased annually for three years until the popula- 

 tion reached a total of four hundred thirty-seven birds (5.3 acres 

 per bird) in the fall of 1932 and held two hundred fifty birds (9.2 

 acres per bird ) into the 1933 breedmg season. With the population 

 at this high level, recovery in 1933 fell to the exceedingly low rate 

 of eighteen per cent. This change in trend resulted in the first de- 

 crease in breeding stock, in 1934. However, productivity then re- 

 turned to a high rate and another irruptive peak was reached. The 

 1933 situation was repeated in the spring of 1935, and the summer 

 productivity also repeated the pattern of two years before. The 

 reduction in both breeding and fall populations reached their low 

 for this decline in 1937, which was the largest decline witnessed. 

 Both figures fell to a point below any year except 1930. However, 

 this decline cannot be compared in intensity with that of 1926-27. 

 The full decline in breeding population from 1935 to 1937 was 

 fifty-four per cent; the decline in the early fall population for the 

 same period was forty-one per cent. From 1937 to 1940 the breed- 

 ing population increased to another peak in 1939^0, dropping again 



