Food hoarding consists of storing food for consumption during times when available food is scarce. If hoarding is present in a population, there should be some benefit derived from it. Scatterhoarders store single food items in many locations throughout their home range and do not actively defend caches. In the southeastern United States, flooding during the winter season 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 how eastern gray squirrels (Sciurus carolinensis) have adapted to a seasonally flooded ecosystem 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. We tracked radio-collared squirrels to obtain information about habitat selection and seasonal survival. Radio-tagged acorns were utilized to determine scatterhoarding locations during the dry season and stomach contents of uncollared squirrels were examined during the winter for diet analysis.
Results/Conclusions
During fall, over 72% of acorns were buried in areas that later flooded. Habitat use did not change during flooding periods; year-round, squirrels were found in dry, hardwoods habitat. Diet did not change between fall and the flooded winter. The winter annualized survival rate for this population was 0.51, which is similar to survival rates in other populations. We also found that mortality was 0.11 times as likely (0.02-0.54, 95% C.L.) for each 1% increase in the proportion of the study area that was flooded (p = 0.004). Thus, this eastern gray squirrel population did not show any behavioral adaptations to seasonal flooding. When radio-tagged acorns were deployed October 2016-February 2017, a tremendous acorn crop was available throughout winter. In the southeastern United States, the warm climate may result in rarely having a food scarce season with no available food. Scatterhoarders may not need to rely on stored food to survive every winter, but rather benefit from this strategy during winters after failed mast crops. With food readily available during winter, the effect of flooding on stored food may not be enough to result in adaptations, but the occasional mast crop failure secures the presence of scatterhoarding within the population.