GROUSE MANAGEMENT 583 



But trees and shrubs, like constructive ideas, take time to grow. Some results of these 

 cultural practices may, therefore, not be fully evident for some years. To bridge this gap. the 

 Investigation also noted the effect, on cover, of cutting, planting, burning and grazing carried 

 on at some previous date in many coverts and under a variety of site conditions. 



Fitting the Factors Controlling Abundance Into the Management Picture 



Before considering the management suggestions that follow, it might be helpful to analyze 

 objectively the factual blueprint research has produced. Its overall design embodies the ten 

 factors that, collectively, determine grouse abundance*. Three of these, the physiology, the 

 reproductive capacity, and the general habits representing the basic characteristics of the 

 species are but little subject to man's control. Yet all are adversely affected by insufficient 

 food and shelter which we, within limits, can influence. Another, weather, while in itself un- 

 controllable, can also have its adverse effects mitigated by assisting Nature to provide the 

 proper environmental setup. 



Disease, so far as can now be determined, is of particular importance only when grouse 

 have been allowed to overpopulate their habitat. A part of the treatment lies in adjusting 

 the yearly harvest so as to leave in the coverts, breeders suflRcient to produce a satisfactory 

 crop for the following year — and no more. This only can be done if the responsible public 

 agency (in the case of New York State, the Conservation Department) has the power to es- 

 tablish the proper seasons, the technically trained men to determine what they should be. 

 the protectors to enforce them and the backing of an interested and an informed public. In 

 addition to this, food and shelter again are important, for a favorable composition and ar- 

 rangement of cover produce healthier birds and tend to distribute them throughout so as to 

 make disease less likely to reach epidemic proportions. 



Predation is more complicated. When grouse are few, every bird taken by predators, as 

 well as by any other cause, may well represent a significant loss. If the reverse is true, a con- 

 siderable number of birds may fall prey to predators without seriously affecting the general 

 level of abundance. 



Normal yearly losses from predators, as recorded by the Investigation, have averaged about 

 40 per cent of the adults. Yet the elimination of such destructive species would not result in 

 saving, for the sportsman, most of these birds unless they were killed in their first fall. 



Of all those that prey on grouse, onlv the goshawk makes grouse a significant part of its 

 diet. The others catch a bird or break up a nest occasionally, but their main reliance for 

 food is on plants or on other animals. The abundance of these "buffer species." then also 

 influences the part predators play in limiting the numbers of grouse. 



It is neither possible nor desirable to eliminate all grouse predators from the coverts. On 

 the other hand, in New York State, if the numbers of great-horned owls, foxes and weasels, 

 where they are overly abundant, could economically be controlled, the harvestable surplus 

 of birds would probably be increased. But such control is not practical over large areas. 



Since losses from predation adversely influence the total grouse population much less in 

 productive than in poor coverts, habitat improvement assumes increased importance. At the 

 same time it seems probable that, on small areas to be managed for intensive shooting, the 

 control of the principal nest predators would result in a greater fall crop of grouse. This 

 would be worthwhile, however, only if the additional birds were harvested for sport. 



* These are physiology, reproductive capacity, general habits, food, shelter, weather, predation, disease, man, artificial propagj 

 tion. 



