802 A CENTURY OF PROGRESS IN THE NATURAL SCIENCES 



spending money on game-range improvement instead of limiting their budgets 

 to wardens, hatcheries, and game farms. 



The literature of the past decade has reflected this change in viewpoint. 

 Among the important recent additions to the wildlife library are books by Gra- 

 ham (1944, 1947), Trippensee (1948), Grange (1949), and Wing (1951), all 

 of which emphasize the management and conservation of land and vegetation 

 as the basis for game production. 



Perhaps of more fundamental importance than the administrative and lit- 

 erary recognition of a scientific basis for game management has been the develop- 

 ment of a body of trained professional men in the field. In 1937 a professional 

 society was formed, called The "Wildlife Society, which began issuing a technical 

 quarterly. The Journal of Wildlife Management. Many universities added 

 trained wildlife men to their staffs, who in turn produced other trained men to 

 fill administrative as well as academic positions. Wildlife management quickly 

 assumed stature as a technical profession, comparable to forestry or the agri- 

 cultural sciences. 



Wildlife Research 



Up to the time of Herbert Stoddard there was a decided separation between 

 the scientific study of natural history and the administrative field of wildlife 

 conservation. After Stoddard's demonstration of how scientific study could 

 guide and orient conservation effort, wildlife research mushroomed into a thriv- 

 ing field of activity. 



Some of the basic questions which have occupied wildlife students in the 

 past and will continue to keep them busy for years into the future are : 



1. Precisely what factors determine or limit wild populations? 



2. How do various cultural operations of land, forestry, agriculture, graz- 

 ing, etc.) affect game populations? 



3. By what practicable means can game populations be increased? 



4. What yields can and should be taken by hunters? 



These seemingly simple queries have proven to be very complex indeed. A 

 digest of the considerable volume of data accumulated to date permits the fol- 

 lowing tentative summary of the field of population dynamics which underlies 

 the whole theory of management. 



Each wild population requires for its existence a number of indispensable 

 components of habitat. These may be categorized under the headings (a) food, 

 (b) cover, (e) water, and (d) special factors, such as grit, dusting facilities, 

 salt, etc. If all of these are present in adequate amounts and in favorable juxta- 

 position a population may exist. If the habitat is favorable, the density of the 

 population will be higli. But if one or more of the environmental factors is 

 limited in amount or in availability the population will tend to be less dense. 

 The average level of a game population is therefore a function of the "carrying 

 capacity" of the local habitat, a term used to express the sum effect of the en- 

 vironment on the population. Thus, one area may support 50 deer per square 

 mile but a similar tract with less forage might support only 30 deer per square 

 mile. Food supply in the latter area is the factor limiting the population. Or, 

 one quail population might be lower than another because cover or perhaps 

 water was inadequate, hence limiting. 



