Investigating factors that set the lower elevational limit of Canada jays (Perisoreus canadensis) on Vancouver Island

Although evidence suggests that climate change will have a major effect on the distribution of species, the abiotic and biotic factors responsible for determining the present range of most species are unknown. The Canada jay (Perisoreus canadensis) is a resident passerine that is limited at the southern edge of its range by climate, via its effect on cached food. To examine the influence of the antimicrobial properties of tree species and temperature on cached food, we conducted two simulated caching experiments. Food cached on Yellow cedar trees (Cupressus nootkatensis) and Amabilis fir (Abies amabilis), retained greater mass than other tree species. We also found evidence that elevation, a proxy for temperature, influences cache preservation. Our results suggest that biotic and abiotic factors can impact the quality of cached food, but we were unable to provide definitive evidence that either was responsible for setting the lower elevational limit of Canada jays.