The Ecology of Scatterhoarding in a Flooded Ecosystem

Abstract

Food hoarding is a strategy typically used by species that experience times with little food readily available. Scatterhoarders store single food items in many locations throughout their home range before the food-scarce season and do not actively defend these caches before recovery during the food-scarce season. In the southeastern United States, flooding during winter is a problem faced by scatterhoarders due to a decrease in dry land available for cache recovery. Understanding how scatterhoarders respond to factors that could influence their supply of hoarded food, such as seasonal flooding, is important given the strong reliance on hoarded food to overwinter survival. We examined diet, hoarding behavior, habitat use, and survival of eastern gray squirrels (Sciurus carolinensis) in a seasonally flooded ecosystem on Lowndes Wildlife Management Area (WMA) in central Alabama. We predicted squirrels would respond to flooding by: storing food during fall in areas that stay dry during winter, seasonally shifting to dry habitat, changing their winter diet, or dying. During the dry season, over 72% of acorns were buried in areas that later flooded. Habitat use did not change during flooding periods; in fact, squirrels selected for habitat that stayed dry during flooding to a greater degree during non-flood seasons, although not significantly so. Diet did not change between the dry fall and flooded winter. We also found squirrels were 7.70 times as likely to die during the flood season (2.28-25.96, 95% C.L.) as the dry season and mortality was 1.30 times as likely (0.26-6.38, 95% C.L.) for each 10% increase in the proportion of the study area that was flooded (both p = 0.001). Thus, this eastern gray squirrel population did not appear to show any behavioral adaptations to seasonal flooding. Further research is needed to fully understand the effects of fluctuating environmental conditions on scatterhoarding behavior and what management considerations should be taken into account for populations living in these conditions.