The Distribution of Bats in Different Ages of Douglas-Fir Forests

Abstract

I examined the distribution of activity of bats in different-age Douglas-fir (Pseudotsuga menziesii) stands in the Pacific Northwest [USA]. Bat activity was higher (P < 0.05) in old-growth forests than in mature or young tree stands. In the southern Washington Cascades, old-growth stands had 2.65-5.67 .times. higher bat activity than younger stands. In the Oregon Coast Range, old-growth stands had 2.54-9.75 .times. higher bat activity. Feeding activity was low in all forest stands and activity by bats occurred during the first 15 minutes of the evening, indicating that bats use old-growth forests only for roosting. Reproductive females were not captured at sites > 3000 m elevation in the Washington Cascades, but were common at elevations > 300 m in the Oregon Coast Range. Reductions in old-growth forests may have a more severe impact on populations of breeding bats in the Oregon Coast Range than in the Washington Cascades.