Salt drive is a seasonal phenomenon common to several classes of wild herbivores. Coincident with shifts of nutrient quality when plants resume growth in the spring, sodium is secondarily lost as surplus potassium is excreted. The beaver (Castor canadensis) is an herbivore whose dietary niche closely follows that of other herbivores that are subject to salt drive, but no published studies to date have assessed the likelihood of its occurrence. To quantify if beavers experience seasonal salt drive, we designed a field experiment to measure the foraging responses of beavers to sodium-enhanced foods. We used sodium-treated (salted) and control (no salt) food items (aspen [Populus tremuloides] and pine [Pinus spp.] sticks) during monthly feeding trials at beaver-occupied wetlands. If conventional ontogeny of salt drive was operant, we expected to observe greater utility of sodium-treated food items by beavers in May and June. Further, if water lilies (Nymphaea spp. and Nuphar spp.) supply beavers with sodium to meet dietary requirements as is widely speculated, we expected foraging responses to sodium-treated food items at wetlands where water lilies were absent to be greater than at wetlands where water lily was present. Aspen was selected by beavers in significantly greater amounts than pine. There was no difference between the mean percent consumed of salted and control aspen sticks by beavers at lily and non-lily wetlands, and no differences in temporal consumption associated with salted or control pine sticks at either wetland type. Salted pine was consumed in greater amounts than unsalted pine. We propose that the gastrointestinal or renal physiology of beavers may preclude solute loss, thereby preventing salt drive.

Background/Objectives: Anthropogenic pressures increasingly fragment populations, reduce connectivity in large mammals, and threaten genetic diversity. Genetic diversity is essential for a population’s ability to respond to environmental change and the long-term persistence of any species. The American black bear (Ursus americanus) is an important ecological regulator of many ecosystems. North Carolina (NC) is home to a large number of black bears that contribute to ecosystem function. In this study, we examined how rapidly changing environmental and anthropogenic effects influence the structure and genetic health of black bears in North Carolina. Methods: Whole genome sequencing data were generated from 82 black bears selected from populations representing two of the three state recognized management units, the Mountain Bear Management Unit (MBMU, n = 49) and the Coastal Bear Management Unit (CBMU, n = 27). Of the 82 black bears, 76 were retained after quality and relatedness filtering. These whole genome sequence data were used to identify almost 900,000 single nucleotide polymorphisms (SNPs) for population genetic analyses. Results: The data identified three genetic clusters, one within the CBMU and two within the MBMU, indicating regional substructure across the sampled populations. Compared with the MBMU, the CBMU exhibited significantly lower genetic diversity and higher inbreeding (p < 2.2 × 10⁻¹⁶), suggesting reduced connectivity and increased genetic vulnerability in the coastal population. Finally, a candidate panel of 4990 SNPs was developed that can be used for the population and individual assignment of black bears. Conclusions: These findings provide a valuable genome-wide resource for black bear conservation in North Carolina and support management strategies aimed at maintaining connectivity, preserving genetic diversity, and promoting long-term population resilience.