Almost any one of the suggestions included can be followed up and expanded 

 •with pleasure and profit (Coues 1877; Seton 1920), and will be found to possess 

 a surprising degree of interest and often of practical importance. 



For information regarding habits of the various mammals, the student is 

 referred to Seton' s Life-histories of Northern Animals (1909), his Lives of 

 Game Animals (1925-1928), to Nelson's Wild Animals of North America (1918), and 

 to the results of many special studies, including those published in the Journal 

 of Mammalogy, Journal of Wildlife Management, and other scientific periodicals. 



Environmental Influence on Mammals 



A. Physical surroundings. 



(1) Soil — kind, composition, texture, color, depth; profile; chemical 



reactions, temperature and moisture at different depths; topography 

 of region; general suitability for mammalian occupation or use; 

 sand dunes, rocics, cliffs, caves, 



(2) Topography — direction and degree of slopes, exposure to sun and wind, 



amplitude and regularity of relief, relations to water bodies, plains, 

 or other features (fig. 3). 



Figure 3. — Aerial photographs are useful to show topography, 

 vegetative types, depths of water, and many other things. 

 The white spots in the upper irtarshes are muskrat houses. 



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