these iinimals play an important part in the ecol- 

 ogy of other wildlife species. Beaver-impounded 

 waters are vised extensively as nursery areas by 

 young red and silver salmon, and provide habitat 

 for waterfowl, moose, and other fur l)earers. No 

 evidence of obstruction to migrating salmon has 

 been found, but this may be due to the presently 

 low numbers of beavers and favorable water levels 

 during the period of salmon migration. 



M/'nk. — Studies on the Kuskokwim Delta indi- 

 cated that the i^resence and condition of pei-ma- 

 frost governs to a large extent the location and 

 success of mink dens, the Alaska Unit rejiorted in 

 1962. Dens are consistently located on frost-free 

 mounds (pingos) or adjacent to streams where 

 the banks are thawed to greater depths. Because 

 of the presence of pernuifrost, drainage is poor. 



and abnormally wet springs and sunnners lead to 

 low mink productivity through den flooding. 

 The "taluyak," a modified fyke net, is used to 

 catch minks in the Kuskokwim Delta region and 

 is more efficient than the standard steel trap. The 

 average catch for the region is 15,000 to 20,000 

 annually, valued at $;175,000 to $500,000. The 

 1961-62 catch of 7,000 is the lowest on record. 



Arctic fox. — Studies in northern Alaska indi- 

 cated that arctic fox populations are presently 

 low, corresponding to a low in the cycle of the 

 brown lemming, the prima I'y prey species. Re- 

 sults of den surveys showed low production of 

 pups during the sunnner of 1962. Pelt studies in- 

 dicated that adult foxes are prime during the first 

 2 weeks of No\ember, whereas yomig animals 

 were unprime at this time. 



-, • S«4». 



Throughout its almost continentwide range the beaver has increased in numbers during the last hvo or three dec- 

 ades. In numerous localities it has "eaten out'" its habitat, creating problems arising from extensive dam breakage 

 and erosion in mountainous country, and stagnating water and deteriorating game-fish habitat in regions of low 

 relief. Low prices for beaver pelts complicate the problem of management. (Photo by Lee E. Yeager) 



33 



