WEIGHT 95 



state or between years for the state as a whole during this period. 



From 1936 through 1940, Dr. A. L. RomanoS conducted for the Investigation a detailed 

 study of annual variations in the development of the embryo*. Slight weight differences year 

 by year among the eggs and among the chicks upon hatching were recorded. Their signifi- 

 cance, however, is not yet clear. 



It is to an expansion of this study of the causes of these less obvious changes in grouse 

 weights year by year as well as to other physiological research that one must look for indica- 

 tions of the part played by food and, indirectly, by weather, in influencing periodic decreases 

 in grouse abundance. Many more eggs and birds will have to be collected over a much wider 

 area, and better techniques for their physical and chemical examination worked out, before the 

 indications that surely exist here of the relationships of these environmental factors to cycles 

 can be adequately outlined or understood. 



Extremes of Grouse Weight 



Few subjects provoke better arguments among grouse hunters tiian does the weight of the 

 largest grouse ever shot. Nearly every year, birds are killed weighing over 1% lb. Pubhshed 

 records on this subject are numerous. "Sus Q. Hannah'"^, who handled many grouse for the 

 markets, claims that the weight "varies from year to year according to circumstances, food, 

 weather, etc." In 1930, there passed through his hands a cock grouse that is said to have 

 weighed 30 oz., even though no unusual amount of food was in its crop. Writing in "Forest 

 and Stream", in 1880, Fellows'" cites a bird killed near Hornellsville, l\. Y., which weighed 

 321/2 oz. A still larger bird which "weighed tliirty-three ounces on tested scales" has been 

 reported"'" as having been killed many years ago in Rutland, Mass. But what seems to be 

 the heaviest bird reliably recorded was weighed by John Burnham'"'. Shot in Essex County, 

 N. Y., in the Adirondacks, it tipped the scales at 2 lb. 4 oz. The Investigation has not 

 weighed one which has approached this Goliath. Males usually weigh more than females and 

 birds two to three years of age more than birds of the year. Probably therefore, all the above 

 records are of old males. 



In the other direction, adults may be reduced to skin and bones and still cling to the 

 breath of life. One female, found in December 1940 in Chenango County, N. Y., and suf- 

 fering from chronic stomach worm infection, weighed but lO'/a oz. (292 grams). Altogether 

 too weak to fly, it was easily caught by hand and died soon after. 



Weight as an Indicator of Health 



Weight is still the best easily available measure of grouse health. Its fluctuations are enough, 

 however, to be confusing. Weight, as an index of condition, must, therefore, be compared 

 with the normal variation encountered among healthy individuals month by month. This 

 differs seasonally as well as among individual birds during one season. But in general, 

 there is a zone of good health (figure 11) extending above and below the average within 

 which variations in the weights of most healthy individuals may be expected to fall. Below 

 this is a danger zone. Weights falling here are apt to indicate environmental difiicuhies or 

 the presence of serious disease. Beyond this danger zone is a critical or lethal zone. Birds 

 whose weights fall within this may seldom be expected to live for long. 



It is recognized, however, that there exists a point above the weight at death below which, 

 due to metabolic and chemical exhaustion, the system will not recover even though the bird 



* See discussion of Embryology, p. 72. 



