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Forest cover has increased greatly in acreage and density in the Eastern and Southern States the last 50 years, re- 

 quiring remedial habitat manipulation practices. In Virginia for example, extensive, fully close<i stands are 

 being opened up by clearing plots in checkerboard design to give additional edge effect and a wider variety of 

 food and cover vegetation. ( Photo by L. G. Kesteloo ) 



tected for their esthetic value. (6) Beaver popii- 

 hitions can be adequately censused from the air 

 by counting the active lodges in the fall of the 

 year. 



Beaver movements and product ivify in sauth- 

 eastern Idaho. — The Idaho l^nit and a beaver 

 trapper employed by the Fisli and Game Depart- 

 ment marked 192 beavers during the first season 

 of fiekhvork. A total of 52 of the marked ani- 

 mals were accoimted for in 1964, and the next 

 trapping season should add considerably to the 

 movements phase of the study. Only 10 beavers 

 showed significant movements. The short&st dis- 

 tance traveled was 2 miles and the greatest was 14 

 miles, all from national forest areas to private 

 land. 



Litter size was detennined by placental scar and 

 fetal counts. Of 1(>.'5 scar counts, an average of 

 3.2 per uterus was recorded over a 4-year period, 

 while 82 litters showed an average of .3.4 fetuses 

 over a 2-year period. Live trapping and carcass 

 examination revealed greater mortality among 

 males than females. In kits tlie sex ratio was 171 

 males per 100 females: in yearlings it was 142 

 males per 100 females: and in adults it was 88 

 males per 100 females. The age-chuss composition 



of 352 beavers was 21 percent kits, 23 i)ercent 

 yearlings, and 56 percent adults. 



Life hixtory of the blark-footed ferret. — The 

 black-footed ferret, never a connnon inliabitant of 

 the Great Plains, is now classified as an endan- 

 gered species. Because of its scarcity, little study 

 has been made of it, and little is known of its life 

 liistorv and habitat re(iiiin'ments, or tlie influence 

 of man's activities, including ranching operations 

 and prairie-dog control. Such infonnation is es- 

 sential for future management and preservation 

 of this weasel. Tiie National Park Ser\ice, tlie 

 Welder Wildlife Foundation, and the Bureau are 

 supporting this research by the South Dakota 

 Unit. 



The Division of Predator and Rodent {\mtrol 

 located a bhu'k-footed fei'ret colony in western 

 South Dakota in 1964. Subsequent field investi- 

 gation revealed the presence of several individ- 

 uals. Tlie.se ha\e been studied to determine their 

 activity and iK'havior and their relation to prairie 

 dogs and other animals. Ol>servations have re- 

 vealed an appreciable volume of new findings on 

 the habits of ferrets, and .some apparent misiu- 

 formaticm in the literature. 



775-625 O— 65- 



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