Microhabitat and landscape characteristics associated with the threatened Allegheny woodrat

Populations of Allegheny woodrat (Neotoma magister) in the northeastern U.S. have declined recently for unexplained reasons. The species is believed to be separate from the more widely distributed eastern woodrat (Neotoma floridana; Ord 1818) and is listed as threatened in Pennsylvania. Several hypotheses have been proposed for the decline in N. magister, but little information on the ecology of the species is available to direct conservation efforts. Using a multi-scale approach, we compared recent microhabitat and landscape characteristics among historical, occupied, and reference sites to pre-1960 versus post-1985 landscape characteristics associated with historical woodrat sites. Our analysis suggests that habitat characteristics, such as percent rock cover and aspect, have affected the current distribution of woodrats in Pennsylvania. Differences in microhabitat probably do not account for the disappearance of woodrats from historical sites. We found no evidence that low levels of human activity near nest sites or that forest fragmentation were directly responsible for the observed decline. But we observed increases in residential and agricultural cover near historical sites between 1950s and 1980s and higher percentages of croplands and other agricultural cover at historical sites than at occupied sites. These land uses are capable of supporting high populations of Great Horned Owls (Bubo virginianus) and raccoons (Procyon lotor). Increased predation by Great Horned Owls and exposure to the raccoon roundworm (Baylisascaris procyonis) have been suggested as potential factors contributing to the decline of woodrat populations in the northeastern United States. Historical sites had significantly higher percentages of coniferous and mixed forest cover than occupied sites, and the percentage of coniferous forest cover at historical sites increased significantly between 1950s and 1980s. Therefore, we speculate that changes in forest composition in Pennsylvania may have adversely affected habitat quality (particularly food availability) for Allegheny woodrats and contributed to their extirpation from historical sites.