in the field to attempt to equal it, but it is of such importance that whenever 

 possible a professional animal photographer should be a member of a field party. 



B-29083 

 Figure 1. — Live trapping is a very useful technic in getting 

 life history data. A 42-pound beaver in trap. 



• Examples of Some Modern Approaches 



Horn (1938: 376). has emphasized the fact that certain seed-eating rodents 

 show a decided preference for seeds of some conifers. In California forests, 

 for example, he 2/ found that the preference is in the following order: Sugar 

 pine, Jeffrey pine, ponderosa pine, white fir, and incense cedar. Ihis pre- 

 ference is in the order of seed size, although that is not the d6Ciding factor, 

 as Horn points out, as the relative acceptability was the same when the seeds 

 were reduced to a paste by grinding. The supply of sugar pine seeds is reduced 

 by timber cutting. The consumption of the seeds by rodents is high. But white 

 fir seeds are abundant. Seeds of the incense cedar are eaten only in small 

 quantities by rodents. As a result, the sugar pine is being replaced by the 

 less commercially valuable white fir and incense cedar. Here, then, is a case 



2/ Horn, E. S. Some California wildlife-forest relationships, U. S. Dept. 

 Int., Fish and Wildlife Service Wildlife Leaflet 275, 5 pp. July 1945^ (Processed^ 



