364 



REPRODUCTIVE CAPACITY OF THE SPECIES 



differences in egg laying, while small, exist and probably result from effects of the environ- 

 ment. 



RENESTING 



The persistency with which the breeding females of a species of bird will renest- — that is, 

 lay another clutch of eggs after one clutch has been destroyed — may well have an important 

 part in determining its population. The mourning dove, for example, makes up for the very 

 small number of eggs laid (only two) by repeatedly renesting over again whenever broken 

 up. The grouse is not so constituted, however. Its ability, or at least its willingness, to try 

 again following an initial failure is very limited. 



The time at which the destruction of the first nest occurs seems to be the factor determining 

 whether or not she will renest. If a hen grou-se loses her clutch during the laying period or 

 a very few days thereafter, it is probable that she will continue laying another set in a second 

 nest. In this case the egg-laying period is merely extended. 



Once the hen has incubated her eggs for several days, the additional yolks that have formed 

 in the ovary begin to be absorbed. Once this process has started, it becomes a difficult 

 matter for the bird to resume laying. Nests thus destroyed generally meant a broodless female 

 for that year. 



This limited probability of renesting woul.-l be less important were it not that most grouse 

 nest destruction by predators occurs during the latter part of the incubation period*. Thus, 

 most destroyed grouse nests are not replaced. On Connecticut Hill, where upwards of 50 

 nests are lost each spring, it is unusual to find evidence of more than half a dozen renests. 

 Those that are found correspond consistently with the number of nests destroyed during the 

 laying period. 



Number of Eggs in Renests 



The size of renest clutches has varied widely but has averaged consistentlv about seven 

 and one-half eggs for all parts of the State, (see table 52). The rather small number of cases 

 observed in any single year makes impossible the finding of any yearly variations that might 

 have occurred. 



• See Chiplec VII, p. 311. 



