Date of Award
Doctor of Philosophy
Striped skunks (Mephitis mephitis) are distributed across much of North America with variable habitat preferences and behaviors recorded throughout their range. Striped skunks also readily adapt to human activity and act as hosts to many common pathogens and parasites that infect other wildlife, domestic animals, and humans. Despite how common striped skunks are in both anthropogenic and natural landscapes, few studies have investigated the influence of human activity on striped skunk ecology, and regional studies of the species in the lower Midwest are uncommon. I captured, radiocollared, and tracked striped skunks in southern Illinois during April 2018-August 2021. I used these data along with camera trap photos, necropsies, and spatial data layers in a GIS to quantify winter denning behavior, pathogen prevalence, habitat selection, and survival. Individual striped skunks used 3-21 unique dens during a single winter and denned consecutively in 1 location for 2-59 days. Three striped skunks participated in communal denning, and ≤3 striped skunks were observed at a den concurrently. Eleven mammalian species were observed at striped skunk dens, and the presence of a striped skunk at a den was positively associated with the presence of Virginia opossums (Didelphis virginiana). Human modification had no significant effect on the number of dens used by a striped skunk, but human modification, distance to stream/shoreline, and mean daily temperature had significant negative effects on striped skunk denning duration. Winter denning behavior of striped skunks in southern Illinois followed the latitudinal gradient of behavior across North America, and dens are a shared resource where direct and indirect intraspecific and interspecific interactions occur. No striped skunks tested positive for canine parvovirus (CPV) or Toxoplasma gondii, 55 striped skunks (83.33%) tested positive for Babesia microti, 24 striped skunks (28.6%) tested positive for Leptospira spp., and 5 striped skunks (6%) tested positive for canine distemper virus (CDV). As distance to permanent water increased, so did probability of infection with Leptospira spp. and CDV, which may be due to pathogen persistence in temporary water sources. No other spatial or temporal covariates affected pathogen presence indicating that pathogen transmission via striped skunks is equally likely across the urban-rural gradient. However, the high prevalence of B. microti indicates further study of vectors is needed in the area. I radiotracked 41 (20 F, 21 M) striped skunks and estimated 3,255 locations (x ̅ per individual =79 ± 43 locations; SD) for analyses of home ranges and habitat selection. Annual home ranges varied in size from 14.2-1196.0 ha (x ̅ =270.5 ±257.1 ha) and annual core areas ranged from 2.7-201.1 ha (x ̅ =55.0 ±48.5 ha). Male home ranges and core areas were larger than those of females (Home range: W =86, P <0.001, Core area: W =85, P <0.001) but did not differ by season (Home range: F3,43 =1.2, P =0.317, Core area: F3,43 =1.3, P =0.276). At the second order of habitat selection, striped skunks preferred developed, grassland/pasture, and forest cover types, areas with less canopy cover, areas with moderate levels of human modification, and spaces closer to permanent water and roads. At the third order of habitat selection, selection by individuals was significant but was so variable that trends were difficult to identify. Although striped skunk preferences are expected to differ across their geographic range, my study indicates striped skunk home ranges and habitat selection within one region can vary drastically, making it difficult to elucidate trends and further reinforcing striped skunks as a quintessential generalist species. I radiocollared 63 striped skunks and tracked them for 6,636 radiodays (x ̅ per individual =105 ± 11 days; SE) for survival analysis. Fifty-seven percent of individuals in my study had unknown fates and 43% were found deceased. I attributed 8% of mortalities to predation, 25% to vehicle collisions, 33% to disease or poor body condition, and 33% to unknown causes. Disease or poor body condition and vehicle collisions are top causes of mortality for striped skunks in other populations. I used the null model to estimate a monthly survival rate of 0.91 (95% CI: 0.87-0.94) and annual survival rate of 0.32 (95% CI: 0.20-0.48). This estimated annual survival rate is similar to reports from other stable striped skunk populations, so I expect it represents a stable striped skunk population in southern Illinois. Overall, my study highlighted variability in striped skunk preferences and behavior across an urban-rural gradient and discussed pathogen transmission implications of this variability.
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