Pilfering of North American Red Squirrel (Tamiasciurus hudsonicus) middens by Northern Flying Squirrel (Glaucomys sabrinus) during spring and summer is unlikely

Résumé

The overlapping ranges of North American Red Squirrel (Tamiasciurus hudsonicus) and Northern Flying Squirrel (Glaucomys sabrinus) and the observation of the latter pilfering fungi from the former’s middens throughout the year in interior Alaska
suggest that kleptoparasitism (resource stealing) could be occurring. Between May and August 2022, we deployed 15 camera traps focussed on active red squirrel middens and nearby reference sites in the central interior of British Columbia, Canada, to document possible nocturnal food pilfering by flying squirrels. Flying squirrels were not detected at red squirrel middens at higher rates than at reference sites. Further, the single observation of foraging-like behaviour in the 12 flying squirrel detections at red squirrel middens suggests that pilfering is unlikely. Epigeal fungi were in apparent abundance during the study period, but not conspicuously stored at middens. The opposing diurnal activity patterns of the squirrels also reduced the likelihood of aggressive territorial behaviour or vigilant midden guarding by red squirrels. Future investigations should focus on the potential for food-pilfering events in relation to local food abundance and on habitat features more likely to contain fungal caches.