Productivity and Populations 301 



partment on the Connecticut Hill area in New York, supplemented 

 by reports of other workers where available. 



Mortality of Grouse Nests. My first year or two of experience in 

 observing the fate of numbers of grouse nests left me feeling quite 

 concerned over the future of the species. It was quite a shock to 

 learn that such a large proportion of the nests were destroyed. Grad- 

 ually it became apparent that what had seemed to be a high rate of 

 loss was actually normal and the birds increased in number at a rapid 

 rate in spite of these losses. Further analysis clearly reveals that this 

 loss is a natural part of the ecology of this species, as are similar 

 losses with many other birds. 



Nest losses are generally high, ranging roughly from one-quarter 

 to three-quarters of all, which indicates a wide variation. The vari- 

 ation occurs on any area in difi^erent years, and also appears to be 

 consistently higher in some areas than in others. On Connecticut 

 Hill, nest losses ranged from thirty-two per cent to seventy-seven 

 per cent over eleven years while nests observed over the state at 

 large showed annual losses ranging from twenty-seven and five- 

 tenths per cent to fifty-six and one-tenth per cent.^ The general av- 

 erage annual loss on Connecticut Hill was slightly under fifty per 

 cent, compared with an average of only about forty per cent over 

 the whole state. This indicates that the Connecticut Hill nest mor- 

 tality has been somewhat higher than the general average (N. Y. S. 

 Cons. Dept. Ann. Reports). 



The nests examined from the Adirondack Mountains had a notably 

 lower mortality rate than for the rest of New York, ranging from 

 seven and one-tenth per cent loss to twenty-four per cent. This is 

 quite logical since the predator pressure in these continuous cover 

 areas is generally lower than elsewhere in the state (data derived 

 from N. Y. S. Cons. Dept. Ann. Reports). 



In west-central Pennsylvania, Studholme ( 1941 ) found the mor- 

 tality of eggs he observed to be twenty-two and five-tenths per cent. 



Almost all nest loss is due to predation. Over the state as a whole, 

 over three-quarters of the nest loss was ascribed to predators, with 

 some cases being unidentified as to cause of destruction. No doubt 

 some of these were the result of predation too. On Connecticut Hill, 



^ This figure is unduly iiffected by the 77 per cent loss on Connecticut Hill and 

 a high loss on tlie Pharsalia area. Excluding the data from these two areas, the figure 

 drops to 31.9 per cent. 



