Evaluating competition between parapatric flying squirrel species: Nest use, parasitism, and the implications of climate change

Northern (Glaucomys sabrinus) and southern flying squirrels (G. volans) are sympatric in Ontario, Canada. I investigated two postulated sources of competition between the species: cavity selection and parasite&dotmediated competition. First I tested whether tree cavities vary in buffering capacity or mean temperature. Cavities do buffer temperature, and show a lagged effect of heating and cooling I then trapped both species in sympatric and a1lopatric sites to model nest selection. Both species preferred softwood trees. Sympatry did not affect cavity selection. Finally, I trapped both species along a latitudinal gradient to measure prevalence of the parasite Strongyloides robustus. S. robustus did infect G. sabrinus, but at a prevalence too low to facilitate competition. G. sabrinus and G. volans do not compete for tree cavities or through parasitism. Nest sharing and low parasite prevalence in Ontario may have facilitated hybridization between these two flying squirrel species.Keywords cavity nest, competition, DBH, decay class, energetics, hardwood, Glaucomys sabrinus, Glaucomys volans, leaf nest, microclimate, Ontario, parasite-mediated competition, softwood, Strongyloides robustus, sympatry, temperature, winter...