Raccoon densities across four land cover types in the southeastern United States

Raccoons (Procyon lotor) are the primary reservoir for rabies virus in eastern North America. Management of rabies in raccoons is achieved primarily with the use of oral rabies vaccination (ORV) and effective ORV bait densities are determined in part by the densities of raccoons. Decisions regarding ORV bait densities, however, are limited by an incomplete understanding of raccoon densities across the spectrum of landscapes they occupy. We carried out a mark-recapture study of raccoons on the Savannah River Site in South Carolina, USA, from 2017-2019, to develop sex- and landscape-specific raccoon density estimates across 4 rural land cover types in the southeastern United States: bottomland hardwood, riparian forest, isolated wetland, and upland pine (Pinus spp.). We captured 404 unique raccoons 773 times over the 3-year trapping period. Estimated densities were 5.44 & PLUSMN; 0.37 (SE) animals/km(2) in bottomland hardwood forest, 2.62 & PLUSMN; 0.32 animals/km(2) in riparian forest, 2.19 & PLUSMN; 0.29 animals/km(2) in isolated wetlands, and 2.14 & PLUSMN; 0.23 animals/km(2) in upland pine. Densities were significantly higher in bottomland hardwood than all other land cover types, whereas densities among the remaining cover types were similar. These patterns are likely the result of landscape fragmentation and configuration, with riparian forests typically embedded in a matrix of less suitable cover types, leading to low densities despite presumably high resource availability. There were higher densities of males than females in every cover type except upland pine, where the sex ratio was balanced. Densities on our site were low compared to other rural areas, which likely results from the lack of human influence in terms of agriculture or development. The financial cost of baiting for ORV distribution may be reduced by considering the comparatively low densities of raccoons in these rural landscapes in the southeastern United States.

Automated summary

Raccoons are the primary reservoir for rabies virus in eastern North America and their densities can affect the effectiveness of oral rabies vaccination (ORV). This study estimated the densities of raccoons in different landscapes in the southeastern United States and found that densities were highest in bottomland hardwood forests. The densities of males were generally higher than females, except in upland pine forests. The low densities observed in this study suggest that the financial cost of ORV baiting can be reduced in these rural landscapes.