Food limitation and habitat preference of northern flying squirrels and red squirrels
Creators: name: Ransome, Douglas Bruce
Publisher: name: University of British Columbia
Year: 2009

description: Food limitation and habitat preference of northern flying squirrels (Glaucomys sabrinus) and red squirrels (Tamiasciurus hudsonicus) were examined in the Montane Spruce (MSdm2) and Engelmann-Spruce-Subalpine-Fir (ESSFdc2) (transition area) biogeoclimatic zones (Meidinger and Pojar 1991) in the south-central interior of British Columbia. I tested the hypotheses that: 1) flying squirrel and red squirrel populations are limited by food availability, 2) flying squirrel abundance is positively related to the abundance of cavities for nesting and, 3) second-growth stands are sub-optimal habitat for flying squirrels and red squirrels. Populations were monitored on 6 study areas; 2 second-growth lodgepole pine stands (controls), 2 second-growth stands with food supplementation (treatments: 25-ha blocks with sunflower seeds aerially applied for 3 summers, starting in June 1991), and 2 old-growth lodgepole pine stands. Northern flying squirrel and red squirrel populations were examined for two summers, starting June in 1992. From hypothesis 1, I predicted that population size, proportion of adults breeding, body weight, recruitment, and survival would be higher in treatment stands that received supplemental feeding than in control stands. Treatment stands had significantly more flying squirrels than control stands (P &lt; 0.00 1). Average densities of flying squirrels were twice as high in treatment stands (1.38 and 1.50 squirrels/ha) than control stands (0.64 and 0.68 squirrels/ha). In 1992, the abundance of red squirrels was not significantly different between control and treatment stands (P = 0.74). In 1993, treatment stands had significantly more red squirrels (P = 0.008) than control stands. The average weight of adult males, survival rates, and the proportions of female and male flying squirrels, and male red squirrels in breeding condition were not significantly different in control and treatment stands. The proportion of female red squirrels in breeding condition was significantly higher in control than treatment stands. Consequently, population size of flying squirrels and red squirrels appeared to be limited by food availability, but individual squirrels did not appear to benefit from food supplementation. An intensive survey of cavities, coupled with subsequent cavity checks, indicated that flying squirrels did not require cavities and their population size was not limited by the availability of cavities. These results do not support the hypothesis that flying squirrel abundance is positively related to the abundance of cavities. Population size of flying squirrels, body weight, recruitment, and survival of flying squirrels and red squirrels were not significantly different in second-growth and old-growth stands. Population sizes for red squirrels were significantly higher in second-growth than old growth stands. There was no consistent difference in the proportion of squirrels in breeding condition between second-growth and old-growth stands. These results do not support the hypothesis that second-growth stands are sub-optimal habitat for northern flying squirrels and red squirrels.