Southern flying squirrel (Glaucomys volans) diet composition in red-cockaded woodpecker (Dryobates borealis) groups in Mississippi and Alabama

Abstract

Southern flying squirrels (Glaucomys volans) are common omnivorous mammals that rely on hardwood forests of the southeastern United States. Diet assessments may aid in understanding their place within food webs and their interactions with the endangered red-cockaded woodpecker (RCW; Dryobates borealis) of which, flying squirrels are a known kleptoparasite and possible nest predator. We examined foods assimilated by flying squirrels collected within RCW-managed forests of the Sam D. Hamilton Noxubee National Wildlife Refuge in east-central Mississippi, Oakmulgee Ranger District of the Talladega National Forest in west-central Alabama, Coosa Wildlife Management Area in central Alabama, and the Sehoy Plantation in east-central Alabama to explore variation in foods assimilated by flying squirrels across a section of the southeast. We used Bayesian mixing models applying isotopic ratios of ^14/15N (δN¹⁵) and ^12/13C (δ¹³C) measured in flying squirrel livers and used potential food items collected at each site to reconstruct their diet. Our model yielded evidence that hickories (Carya spp.) and oaks (Quercus spp.) contributed the most to the diet of southern flying squirrels at Noxubee, Oakmulgee, and Coosa with insects comprising the bulk of the diet at Sehoy (n = 39 squirrels). The proportion of hardwoods surrounding areas where flying squirrels were collected (10–52%) contributed little to model performance. Trophic positioning analysis showed a 95% confidence interval overlap between all sites indicating that flying squirrels are likely primary consumers and/or secondary consumers (trophic position of 3; 2.60–3.74). Flying squirrels in our study likely consume a mix of plants and insects and are unlikely to be common tertiary consumers (ex. consuming insectivorous-bird eggs). Their omnivorous habit suggests that efforts to exclude flying squirrels from RCW habitat will need a multifaceted approach with diet item management (ex. hardwood removal) as a part of the possible solutions available.