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.

Master of Science / Department of Biology / Samantha Wisely / As human populations increase world-wide, land use and land cover are altered to support the rapid anthropogenic expansion. These landscape alterations influence patterns of zoonotic infectious disease emergence and propagation. It is therefore becoming increasingly important to study emerging and re-emerging diseases to predict and manage for future epidemics. Studies of directly-transmitted infectious diseases should consider three components of disease epidemiology: characteristics of the pathogen, ecology of the host, and habitat configuration of the underlying landscape. I studied the influence of both the host ecology of the striped skunk (Mephitis mephitis) and the alteration of the underlying landscape on the epidemiology of rabies virus in the Flint Hills of Kansas. This tall-grass prairie is experiencing woody expansion due to anthropogenic disturbance, altering the landscape on which the rabies virus emerges and spreads. We first studied the behavioral and social ecology of the striped skunk using field and genetic methods. We concluded that 1) striped skunks reached high population densities in anthropogenically disturbed habitats, 2) these individuals were not closely related, and 3) contact rates could be influenced by temperature. Using habitat-specific skunk densities from this initial study, we created spatially-explicit contact networks of skunk populations across the Upper Kansas River Watershed and simulated the emergence and spread of rabies through the system. This modeling approach revealed a threshold of forest habitat beyond which striped skunks became increasingly connected and the rabies virus reached greater extents across the landscape. Based on these findings we recommend fire regimes and land cover alterations to reduce woody encroachment across the Flint Hills and to avoid future disease epidemics in the region.

<p>The principle objective of this investigation was to develop an understanding of the physiological response and ecological aspects of winter torpor of small carnivores, specifically striped skunks (<i>Mephitis mephitis</i>) in the northern environment. An experiment was undertaken to investigate the physiological response of skunks to solitary and communal over-winter strategies. Solitary skunks were able to undergo daily torpor to conserve energy to survive the winter, whereas communal skunks were able to use social huddling to reduce energy expenditure and rarely entered torpor. Due to seasonal changes in life requirements, den selection criteria change throughout the year. I examined the landscape metrics and habitat characteristics surrounding dens to evaluate the hierarchical selection and use of dens during winter (i.e., for torpor) and summer (i.e., for parturition). Den structures commonly used for winter dens were buildings, whereas den structures used for maternity dens were rockpiles and underground burrows. Habitat surrounding den sites influenced den use; animals chose den sites closer to roads, water sources, habitat edges, and crop fields. Seasonal movements of skunks from winter dens to the following summer home ranges were examined with respect to winter grouping (i.e., solitary or communal) and winter den structure (i.e., underground burrow or building) to investigate factors that influence spatial distribution of skunks. Male and female skunks moved similar distances (~1.5 km) from winter dens to the center of home ranges established in summer, irrespective of winter grouping status and winter den structure use. Due to limited movement in spring, skunks from communal winter dens had higher spatial overlap of summer home ranges than did skunks from solitary dens, producing spatial aggregation of skunk activities surrounding winter communal den sites. Consequently, winter communal dens represent localized hotspots in the landscape. The effects of extrinsic variables (i.e., environment and diseases) and intrinsic characteristics (i.e., age, gender, and body condition) on cumulative winter survival rate were examined. Winter survival rates were driven mostly by winter condition (i.e., low ambient temperature and snow depth), rabies, and body condition. These results suggest that winter severity probably poses a limit on the northern distribution of the species.</p>

<p>The principle objective of this investigation was to develop an understanding of the physiological response and ecological aspects of winter torpor of small carnivores, specifically striped skunks (<i>Mephitis mephitis</i>) in the northern environment. An experiment was undertaken to investigate the physiological response of skunks to solitary and communal over-winter strategies. Solitary skunks were able to undergo daily torpor to conserve energy to survive the winter, whereas communal skunks were able to use social huddling to reduce energy expenditure and rarely entered torpor. Due to seasonal changes in life requirements, den selection criteria change throughout the year. I examined the landscape metrics and habitat characteristics surrounding dens to evaluate the hierarchical selection and use of dens during winter (i.e., for torpor) and summer (i.e., for parturition). Den structures commonly used for winter dens were buildings, whereas den structures used for maternity dens were rockpiles and underground burrows. Habitat surrounding den sites influenced den use; animals chose den sites closer to roads, water sources, habitat edges, and crop fields. Seasonal movements of skunks from winter dens to the following summer home ranges were examined with respect to winter grouping (i.e., solitary or communal) and winter den structure (i.e., underground burrow or building) to investigate factors that influence spatial distribution of skunks. Male and female skunks moved similar distances (~1.5 km) from winter dens to the center of home ranges established in summer, irrespective of winter grouping status and winter den structure use. Due to limited movement in spring, skunks from communal winter dens had higher spatial overlap of summer home ranges than did skunks from solitary dens, producing spatial aggregation of skunk activities surrounding winter communal den sites. Consequently, winter communal dens represent localized hotspots in the landscape. The effects of extrinsic variables (i.e., environment and diseases) and intrinsic characteristics (i.e., age, gender, and body condition) on cumulative winter survival rate were examined. Winter survival rates were driven mostly by winter condition (i.e., low ambient temperature and snow depth), rabies, and body condition. These results suggest that winter severity probably poses a limit on the northern distribution of the species.</p>

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