Flying squirrel (Glaucomys sabrinus and Glaucomys volans) habitat use and ecology in landscapes managed with partial harvesting silviculture in central Ontario

Northern and southern flying squirrels are used as indicator species of sustainable forest management in many regions of North America, including Ontario. However, little is known about flying squirrel ecology or the impacts of partial harvesting on their populations in northeastern North America. I investigated flying squirrel habitat use at multiple spatial scales in both logged and unlogged forests through live-trapping and radio-telemetry. Live-trapping data was used to develop habitat models at the stand and landscape scale for both flying squirrel species, and additionally for red squirrels and eastern chipmunks. I also conducted dietary analyses for all sympatric tree squirrel species, and investigated flying squirrel nest use, home range size, and resource selection within home ranges with radio-telemetry. Northern flying squirrel densities were significantly lower on shelterwood harvested stands compared with unharvested pine stands, which appears to be a consequence of significantly lower densities of large snags, spruce and hardwood trees, and lower understory stem densities on shelterwood cuts. Large hardwood snags were a key nesting substrate for northern flying squirrels. Spruce may be a crucial resource to northern flying squirrels; it is the primary host tree of the mycorrhizal hypogeous fungi which dominated their diet, and northern flying squirrel density and habitat use was associated with spruce tree density at multiple spatial scales. In contrast to northern flying squirrels, southern flying squirrels demonstrated little evidence of a negative response to partial harvesting. This species seems to tolerate lower snag densities in recent selection cuts by nesting in natural and abandoned woodpecker cavities in live trees. Mast availability had a significant influence on southern flying squirrel density at the landscape scale, and on habitat use within home ranges. Southern flying squirrels had a diverse diet in central Ontario (fungi, pollen, seeds, and insects). In order to obtain these varied food resources, this species was active at night in areas with higher tree species diversity than random sites. This study supports past research indicating that northern flying squirrels are associates of mature and old forests (90+ years old); whereas southern flying squirrels demonstrated more flexible habitat use and behaviour.