shelter 77 



to be fully reliable. The majority of nests are iii cover with open 

 iinderstory and the mortality in these is average. The mortality in 

 cases having a dense understory was very excessive. The possibility 

 exists, and is logical, that a dense imdergrowth tends to increase 

 nest mortality. Again, the habit of the giouse in avoiding nest sites 

 where the understory is dense may be conditioned by the predator 

 hazard. 



RELATION OF SHELTER TO GROUSE BROODS 



Cover Type Preferences of Grouse Broods. Families of young 

 grouse observed up to tlie end of September may be considered as 

 broods. Since the location of the family and its activities are deter- 

 mined by the needs of the young birds, the mother bird is considered 

 a part of the gioup. So many of the requirements of the young birds 

 differ from those of the adults that it would be likely that their 

 shelter requiiements would di£Fer; and since their food habits vary 

 markedly from the old birds, the cover types chosen also may well 

 vaiy considerably. What are tlie cover type preferences of the 

 chicks as they grow up, and how do they vary from the cover chosen 

 by adults by themselves in the summer? The records of 1,515 brood 

 observations in New York from 1930-1936 are given in Table 2 

 (Bump, 1938). 



Table 2 



Cover Types Selected by Grouse Broods in New York, 1930-1936 



Flushes per Acre Reduced 

 Percentage of Total to Part of Most Used Type 

 Cover Type Flushes Taken as 1.00 "^ 



Chicks Adults 



Overgrown land 44.7 1,00 .61 



Slashings 12.4 .65 .72 



Hardwood woods 25.5 .22 1.00 



Coniferous woods 4.2 .22 .17 



Mixed woods 10.4 .17 ,25 



Open land 2.9 .06 !o3 



It is clear that the tendencies in cover type use in summer by 

 young and old biids is similar-a definite preference for the brushy 

 types, primarily overgrown land, followed by slashings. This tend- 



^ Figiires derived from Connecticut Hill data. See Bump, 1938. 



