Characteristics of northern flying squirrel populations in young second- and old-growth forests in western Oregon

ROSENBERG, D. K., and ANTHONY, R. G. 1992. Characteristics of northern flying squirrel populations in young secondand old-growth forests in western Oregon. Can. J. Zool. 70: 161-166. We compared density, sex ratio, body mass, and annual recapture rate of northern flying squirrel (Glaucomys sabrinus) populations in second-growth and old-growth Douglas-fir (Pseudotsuga menziesii) stands in the Oregon Cascade Range. Densities averaged 2.0 and 2.3 squirrels/ha in secondand old-growth stands, respectively. Although densities varied between years within stands, average densities were similar between years. Body mass and annual recapture rate were similar between stand-age 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 be habitat generalists, and not a species associated with old-growth stands, as was previously hypothesized. We suggest that studies be carried out with radiotelemetry to more accurately assess the habitat associations of this species.