Aspects of beaver (Castor canadensis) ecology in eastern South Dakota

Aspects of beaver (Castor canadensis) ecology were investigated during 2000 and 2001 along a section of the Big Sioux River in eastern South Dakota. Grazed and ungrazed habitat quadrats were sampled for tree species, diameter of trees at breast height (DBH), beaver damage to trees, and distance from water of trees and damage.;Beavers cut trees in equal proportions between grazed (17.4%) and ungrazed habitats (15.4%). The number of trees cut/ha was greater in ungrazed habitat (164.5 trees cut/ha) than in grazed habitat (97.1 trees cut/ha). Beaver activity was evident on 85 of 527 (16%) trees sampled. Green ash, peachleaf willow, and American elm were selected for by beavers. The mean DBH for trees cut (30.82 cm) was significantly smaller than that of uncut trees (42.23 cm). The mean distance from the water of cut trees (20.34 m) was less than that of uncut trees (26.86 m).;I examined 103 beaver carcasses for age and sex. The age ratio was 32% (33) kits, 22.3% (23) yearlings, and 45.6% (47) adults. There was no significant difference in the sex ratio of from the 1:1 ratio in the entire population or between age classes. (Abstract shortened by UMI.)...