INBREEDING 



367 



The higher average losses in Connecticut Hill renests compared with all others must be 

 discounted owing to the small number of observations involved. 



The differences in average embryo loss in first nests and in renests is considerable, being 

 nearly three times as great in the second nests. However, it is still only an additional 2.2 per 

 cent of all the fertile eggs and does not involve losses of importance. 



It must be concluded, likewise, that all lossss from embryonic death are of minor impor- 

 tance as compared with many other causes of grouse mortality. 



A NEST FULL OF GROUSE CHICKS JUST HATCHED (SEVERAL SHELLS REMOVED BY PHOTOGRAPHER) 



INBREEDING 



A pet bug-a-boo commonly suggested in recent years, as a possible contributing cause of 

 the grouse cycle, is inbreeding. It was first mentioned by Stoddart'" but has since received 

 more and more attention in succeeding years. To many it seemed simple and logical. The 

 sedentary habits of the bird in times of high populations was thought to result in breeding 

 within families. This, in turn, was said to cause deterioration of the species and sharply 

 reduced numbers. 



The concept does not stand up well in the light of numerous pertinent facts. 



In the first place, inbreeding is not necessarily detrimental to the offspring. Only when 

 the parents possess serious genetically transmissible defects could inbreeding be a problem. 

 As Leopold'™ points out, wild species are of relatively pure strain and the likelihood of serious 

 consequence from inbreeding is much less than in domestic animals where little natural 

 culling takes place. 



Inbreeding may operate to a species' benefit as well as detriment. It has proved useful 

 in developing superior strains of some domestic animals. 



If it were to injure wild animal populations, one may assume that it would show up 

 quickly in isolated populations. Here, the opportunity for inbreeding would be greatest. 

 Such might be the case where birds were stocked in a habitat not previously occupied by 



