Native Predator Study

Hi! My name is Valerie Rice when I worked at the Red Wolf Sanctuary I also completed this study as part of my coursework with Miami University's Project Dragonfly Graduate Program. This study compares the relative abundance of native predators in woodland and riparian habitat found on Red Wolf Sanctuary's property. This blog post contains a synopsis of my study.

Mingo a resident bobcat of the Sanctuary | Photo by Valerie Rice

Introduction

An extremely important concept for conservation is species richness, which means that there are a lot of different species living in one area. Areas with high amounts of species richness are foundational for land management and wildlife conservation initiatives.  According to Fleishman et al., if a location with a high amount of diverse species is protected, the species that live there will be conserved (2005). A variation in types of organisms living in an ecosystem helps the resources in that environment to be utilized with the least waste (Bohn and Huth, 2017).  

There are many factors which determine the species richness of a habitat.  One factor is the Habitat Heterogeneity Theory. According to this theory, habitats that have an intricate structure may increase resources such as food, and niches, which will increase species richness (Lack, 1969).  As stated by Stauffer and Best, riparian habitats are those that contain, or are located close to bodies of water such as streams or creeks (1980). As determined by the United States Forest Service, a riparian area includes all areas within a horizontal 100ft distance from the edge of a body of water (2000).  While woodland habitat has similar vegetation to a riparian habitat, it does not have a close proximity to bodies of flowing water. Both woodland and riparian habitats support various species of vegetation. 

The purpose of my study was to inspect native predator species richness between a riparian and woodland habitat.  Is there a greater species richness of predatory species in a woodland or riparian habitat in Southeastern Indiana in the fall?  I believe the riparian habitat will house more species richness of native predators, as the habitat is more structurally complex and also contains water, a valuable resource.

Throughout my study a working definition of “native predators” will be used.  While native predators typically includes any animal that is native to an area and preys upon/consumes other animals, for the purpose of this study the term will only pertain to terrestrial predators native to Southeastern Indiana.  I will also be including opportunistic terrestrial omnivores such as raccoons and opossums in my definition. Native predators that can be found in Southeastern Indiana are coyotes, red foxes, bobcats, and mink, as well as many others.

My study is important as rural areas are becoming more and more developed.  Rising Sun is a small town, with an approximate population of 2,144 people (U.S. Census Bureau, 2018).  The town boasts a casino, and currently has several development projects including condos and apartment complexes.  By examining the species richness of native predator species in this area, we can begin to study the effects of development.  Increased development of urban areas also increases the chances of human-wildlife conflict; as the habitat of native animals is replaced by urban areas those animals are often forced to live in close quarters with humans (Poessel et al., 2013).

Methods

I collected my data via camera traps, which captured the appearances of animals in photographs.  The camera traps were located on the property of the Red Wolf Sanctuary in Rising Sun, IN. Two camera traps were located in a riparian habitat, and two were located in a woodland habitat.

Photos were accumulated over the course of three weeks, from October 2, 2019 to October 23, 2019.  This study occurred for a total of 21 continuous days. During this period of time the traps were not disturbed.  I grouped the images by species. Unidentifiable animals were also given a group. To reduce the possibility of counting the same individual twice, consecutive images containing a certain animal were counted as one observation until the animal moves out of the frame of the camera.  If the images were more than 10 minutes apart they did not count as the same individual. I grouped fox and grey squirrels as “squirrels” due to the fact that it was difficult to distinguish color and type of squirrel in some of the images.

Results

I collected my camera traps on October 23, 2019.  The total number of images containing an animal was 403.  I sorted images by habitat type and species (Table 1).

Discussion

Species richness looks at the total amount of different species in a habitat, regardless of how large or small the populations of those species are.  Species evenness examines the different proportions of each species, taking into account the other species in the habitat, as well as species richness.  When species richness is combined with Shannon’s Diversity, evenness can be calculated. Evenness measures how evenly individuals are distributed among the different populations.  My results suggest that the individuals observed in the riparian habitat are more evenly distributed across species than those individuals observed in the woodland habitat.

As mentioned, Shannon’s Diversity Index considers both the abundance and evenness of the species present in a habitat (Beals, Gross, Harrell, 2000).  My results suggest that the riparian habitat has a greater diversity than the woodland habitat.  The relative abundance for native predators was calculated to be 1% for the woodland habitat, and 48% for the riparian habitat. While native predators were observed in both habitat types, the riparian habitat has a higher relative abundance as 48% is greater than 1%.

Conclusion

The data gathered by my study suggest that native predators have a higher relative abundance in riparian habitats than woodland habitat.  It should be taken into consideration that only two camera traps were set up in each location.  Individuals who happened to walk through their range were observed, but those who did not cross the path of the camera traps were not observed and were not taken into account for the results of this study.  The results of my study may be used in the future to examine the relative abundance of native predators vs the relative abundance of prey species.

I’m very happy with the results of this study.  I didn’t expect to find a bobcat or red fox during this study (Image 5).  I also didn’t expect so many raccoons to be observed in the riparian habitat.  While I have seen their tracks in the mud by the creek before, I have only physically seen them in woodland habitat. 

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Sources

• Beals, M., Gross, L., & Harrell, S.  (2000). Diversity indices: Shannon’s H and E.  Retrieved from http://www.tiem.utk.edu/~gross/bioed/bealsmodules/shannonDI.html

• Bohn F., & Huth A.  (2017). The importance of forest structure to biodiversity–productivity relationships. Royal Society Open Science. 4(1):160521. 

• Fleishman, E., Thomson, J., Nally, R., Murphy, D., & Fay, J. (2005). Using indicator species to predict species richness of multiple taxonomic groups. Conservation Biology. 19:1125-1137.

• Lack, D. (1969).  The numbers of bird species on islands.  Bird Study.  16:193–209.

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• Poessel, S.A., Breck, S.W., Teel, T.L., Shwiff, S. , Crooks, K.R. & Angeloni, L. (2013). Patterns of human–coyote conflicts in the Denver Metropolitan Area. The Journal of Wildlife Management.  77:297-305. 

• Stauffer, F., & Best, L. B. (1980). Habitat selection by birds of riparian communities: evaluating effects of habitat alterations. The Journal of Wildlife Management. 1-15. 

• Taylor, D.R., Aarssen L.W. & Loehle C. (1990). On the relationship between r/K selection and environmental carrying capacity: a new habitat templet for plant life history strategies. Oikos 58: 239−350.

• U.S. Census Bureau.  (2018). Annual Estimates of the Resident Population: April 1, 2010 to July 1, 2018 - 2018 Population Estimates. Retrieved from: https://factfinder.census.gov/faces/tableservices/jsf/pages/productview.xhtml?src=CF

• U.S. Department of Agriculture Forest Service (USFS).  (2000). Forest Service Manual, Title 2500, Watershed and Air Management. Section 2526.05. Washington, DC: USDA Forest Service.

• Wandrag, E.M., Dunham, A.E., Duncan, R.P., & Rogers, H.S.  (2017). Dispersal drives tree seedling distributions. Proceedings of the National Academy of Sciences. 114:10689-10694; DOI:10.1073/pnas.1709584114