Neonatal animals feature heavily in admissions to wildlife rehabilitation centers. Orphaned young animals typically make up the largest proportion of cases seen by individual facilities (Long et al. 2020, Mullineaux 2014). Some of these animals are misidentified as orphans and mistakenly taken from their mothers, which is a common problem among wildlife care facilities (Tseng 2011, Found an Animal… c2020, Found an Orphaned… c2021, Mass.gov c2021). This creates an issue for both the animals brought in and the facilities housing them. Healthy, young wildlife receive more optimal care with their mothers than they would under human care, and these animals can miss out on learning experiences needed to survive in the wild, such as forming social groups and successfully avoiding predators (Guy et al. 2013, Robertson and Harris 1995). Additionally, wildlife clinics tend to have limited funds, so there is a need to reduce the intake of unnecessary patients to adequately allocate resources to animals truly in need (Santos et al. 2018, Orphaned and… c2021, Sleeman 2008).
These issues highlight an opportunity for conservation education centered around the proper identification of orphaned mammals that require professional intervention. In this study, we elected to focus on orphaned mammals and identify the areas in Champaign County where these animals were most frequently found and subsequently brought into the University of Illinois Wildlife Medical Clinic (WMC). We then aimed to compare the orphans’ found locations with socioeconomic factors to characterize the human population that most often brings these animals to the WMC. This comparison will help identify areas to target for outreach and the background of the people most likely to bring in orphaned mammals.
The most abundant mammalian species brought into the WMC are the eastern cottontail (Sylvilagus floridanus, SYFL), eastern gray squirrel (Sciurus carolinensis, SCCA), Virginia opossum (Didelphis virginiana, DIVI), and common raccoon (Procyon lotor, PRLO). These four species were chosen as a representative sample of orphaned mammals brought to the WMC from Champaign County, Illinois. We made predictions for the human socioeconomic factors most associated with where the animals were most commonly found based on their natural history.
Both the common raccoon and the Virginia opossum are omnivorous, opportunistic species with broad dietary and habitat requirements (Chapman and Feldhamer 1982, McKinney 2002). These species can often be found in edge habitats with a mixture of farmland and woodland, but they are less common in grasslands or agricultural areas due to the reduction in trees and sources of shelter (Mammals n.d.). Raccoons and opossums are generalist mesopredators that respond positively to anthropogenic resources (McKinney 2002, Prange and Gehrt 2004). Urban raccoons and opossums have adapted their diets to take advantage of newly available foods (Outdoor Illinois… 2019). Both species are tolerant of fragmentation and human presence and, therefore, can commonly be found in urban and suburban areas (Crooks 2002, Mammals n.d.). Raccoons specifically have been found to reach higher densities in urban areas than rural areas (Hoffmann and Gottschang 1977, Rosatte et al. 1991, Prange and Gehrt 2004). Thus, it was expected that both opossums and raccoons would be more commonly found in areas of high human population in Champaign County because they are adapted to the human population, can successfully use resources available in human areas, and tend to be more abundant in urban habitats.
The population of eastern gray squirrels in Illinois has decreased due to the loss of mature wooded habitats, but they are still abundant throughout the state (Mammals n.d.). Gray squirrels are typically found in dense woods, but they have adapted to urban areas and are also frequently cited as nuisances in urban situations (Chapman and Feldhamer 1982, Illinois Natural… c2021). Although they can be found in both rural and urban areas, landscapes in Illinois must be at least 20 percent forested to possess gray squirrels (Nixon et al. 1978). In previous studies, gray squirrels were most abundant in areas with extensive canopy cover (Bonnington et al. 2013, Williamson 1983). The greater canopy cover allows increased protection from predators while the seed-bearing tree species provide an important food source (Williamson 1983). Moreover, a study looking at radio tracking of gray squirrels in an urban forest found that they consistently avoided developed and open grassy portions of the habitat (Tounzen et al. 2012).
Eastern cottontails inhabit a wide variety of diverse locations including disturbed, successional, and transitional habitats (Flux and Chapman 1990). Despite the loss of habitat to agriculture and development, cottontails remain abundant in North America (Chapman et al. 1982). Predation is a factor that limits populations in fragmented landscapes (Smith and Litvaitis 2000). Therefore, cottontails are commonly found in open spaces near woody cover, but they can be found in urban areas with brush piles, shrubs, or tall grasses nearby where they can take cover from predators and inclement weather (Mammals n.d.). In terms of foraging, cottontail rabbits have higher foraging activity the closer they are to cover, generally preferring to forage under the cover of shrubs compared to trees (Abu Baker et al. 2015). Cottontails may be excluded from urban areas that lack low scrub understory, weed patches, and brush piles for refuge sites, or areas that have fences blocking escape routes (Abu Baker et al. 2015).
Forest cover is generally inversely related to higher human population and housing density (Mockrin et al. 2019, Heynen and Lindsey 2003, Troy et al. 2007, Luck et al. 2009). Thus, we would expect that eastern gray squirrels and eastern cottontails would be more abundant in areas of a lower population due to the increased availability of trees and brush, as well as the decreased abundance of predators. Based on most of the available literature on the natural history and habitat of these animals, both eastern gray squirrels and eastern cottontails were expected to be more abundant in lower human population areas of Champaign County.
Education attainment and income are related to human population density. Population decline is associated with increases in income inequality (Butler et al. 2020). Rural regions throughout the United States have consistently experienced high poverty rates related to geographical isolation and lack of economic opportunities (George 2014). In Illinois, rural areas have a higher poverty rate, lower education, and higher unemployment rate than urban areas (Selected Social… 2018). Therefore, areas with lower population density would be expected to have lower socioeconomic status with lower income and lower education levels.
We formulated hypotheses based on the backgrounds of the four species of focus and their relationship to human population density. Based on the expected human population density each species would be found at, we made predictions for the expected income and education levels that would correlate with population. We hypothesized that Virginia opossums and common raccoons would be found in areas of high human population, high income, and high education, while eastern gray squirrels and eastern cottontails would be found in areas of low human population, low income, and low education. Our study objective was to evaluate the impact of human population density, education level, and wildlife habitat on the possibility of each orphaned species to be brought into the wildlife clinic.