WINTER USE OF DOUGLAS-FIR FORESTS BY BLUE GROUSE IN COLORADO

In Pseudotsuga menziesii forests, Dendragapus obscurus concentrated spatially, but there were no consistent differences related to basal area of tree species, conifer stem densities, and topography that were common to both areas. Blue grouse used dense (2000 stems/ha) second growth (40-75 yr old), open to dense (200-1900 stems/ha) mature (100-200 yr old), and open (<100 stems/ha) old-growth (200-600 yr old) stands. Stands used were composed of Douglas-fir alone or in association with subalpine fir Abies lasiocarpa, Engelmann spruce Picea engelmannii, lodgepole pine Pinus contorta, limber pine P. flexilis, Rocky Mountain juniper Juniperus scopulorum and quaking aspen Populus tremuloides. Grouse used stands on mesic N and E aspects, on xeric S and W aspects, at elevations of 2530-2960 m, and on slopes of 1-45o. Preferential use of Douglas-fir trees occurred within stands that had an abundance of limber pine (use = availability) and subalpine fire (use < availability). Large Douglas-fir (20-90 cm dbh) were preferred within stands that had an abundance of smaller (≤15 cm dbh) trees. -from Authors