CHARACTERISTICS OF NORTHERN FLYING SQUIRREL POPULATIONS IN YOUNG 2ND-GROWTH AND OLD-GROWTH FORESTS IN WESTERN OREGON

We compared density, sex ratio, body mass, and annual recapture rate o f northern flying squirrel Glaucomys sabrinus) populations in second-g rowth and old-growth Douglas-fir (Pseudotsuga menziesii) stands in the Oregon Cascade Range. Densities averaged 2.0 and 2.3 squirrels/ha in second- and old-growth stands, respectively. Although densities varied between years within stands, average densities were similar between y ears. Body mass and annual recapture rate were similar between stand-a ge classes, although a higher proportion of females was recaptured in subsequent years in second-growth than in old-growth stands. Similarly , there was a higher proportion of females than males in second-growth but not in old-growth stands. Squirrel densities were not correlated with habitat characteristics; we concluded that flying squirrels may b e habitat generalists, and not a species associated with old-growth st ands, as was previously hypothesized. We suggest that studies be carri ed out with radiotelemetry to more accurately assess the habitat assoc iations of this species.