Biological Projects

Beaver Cache Surveys

Togiak National Wildlife Refuge reinstated beaver abundance surveys on 12 rivers in fall 2002. Beaver abundance surveys had formerly occurred on four river drainages from 1975-1987. The number of food caches, which indicate an active beaver colony, are tallied, creating an index of beaver abundance. Food caches are defined as submerged piles of branches, typically surrounded by water (Hay 1958), stored in the fall for winter food. The aerial survey takes place each autumn after leaf fall, and before freeze up on the main channels of each river.

Beavers have historically been the most important furbearers in the area and have also been an important historical food source for residents. Beavers are abundant throughout the refuge, occurring in all major drainages and in most of the smaller tributaries.

Resources:

Hay, K. G. 1958. Beaver census methods in the rocky mountain region. Journal of Wildlife Management. 22: 395-402.