Assessing the spatial distribution and habitat associations of three focal species in a mixed disturbance landscape

Background/Question/Methods

Mid-sized mammalian generalists, who exploit a variety of food resources, occupy a pivotal role in ecosystems by preying on a variety of small mammals, reptiles, amphibians and birds while simultaneously being prey for larger carnivores such as coyotes, owls and raptors. The Oak Openings Region of northwest Ohio is composed of heterogeneous habitats which support diverse species which are vulnerable to impacts from omnivores. Focal species for this study are three locally common omnivores, the raccoon (Procyon lotor), (Didelphis virginiana) Virginia opossum and (Mephitis mephitis) the skunk. Our research focuses on the spatial distribution and habitat associations of our three omnivore species in three Metroparks within the Oak Openings Region. We used vegetation surveys, road kill surveys and night surveys to explore these distributions. Vegetation surveys were trail based and repeated twice during field season. Variables measured were vegetation density, canopy cover, plant diversity, dominant tree species and litter depth. Road kill surveys included weekly driving of roads within and adjacent to the parks and recording location and species for each carcass found. Night surveys involved walking trails within the parks from sunset onward recording location, species and group size for each animal sighted using flashlights and a handheld spotlight. 

Results/Conclusions

Parks and trails within parks were significantly different for all vegetation variables except for litter depth and plant diversity. This shows that there is much habitat heterogeneity within and between parks. The road kill surveys yielded 292 sightings of deceased animals. Of these, 68% were focal species. Oak Openings Metropark accounted for the highest proportion of the road kills both in focal and non-focal species. Secor had more focal animals killed than Wildwood but fewer non-focal animals. There appear to be several clusters on the roads around each park. The night surveys yielded 1094 sightings of animals. Of these 30% were of focal species. A large fraction (86%) of non-focal species sightings were of deer. Parks and trails within parks significantly differed in focal species /km sighted (p<0.05) and in non-focal species / km sighted (p<0.05). Overall Oak Openings Metropark accounted for the most sightings (881) and Secor the least (72). There appear to be different seasonal peaks in sightings for focal and non-focal species. There also appear to be several areas of clustering within each of the parks. Our findings support the trend of larger, more heterogeneous areas supporting larger populations of mammals.