Research by wildlife student David Garst incorporates geographical information system technology to help him provide important information on the timber rattlesnake for the Virginia Department of Game and Inland Fisheries.
These timber rattlesnakes, only rattlesnake of the Appalachia area, are essential to the environments in which they live.
The ecosystem balance they help maintain is primarily achieved by helping control the rodent population. Their role helps maintain healthy balances necessary for retaining healthy natural areas: They fill both the role of top-tier predator and the role of prey.
Not only does the rattler act as a high-end predator, controlling the rodent population, including mice, chipmunks, and squirrels, the snake is prey for hawks, owls, and opossums. These snakes are an essential part of the ecosystem.
“A few hikers killing a single snake is not the main problem,” says Garst. “We are eliminating necessary habitats for the timbers by creating more roads. As we continue to develop mountainous areas, the timber’s food source and potential living area dwindles.”
Trying to help conserve and restore the timber, Garst used a geographical information system, commonly referred to as GIS, to make known locations of timbers along with field measurements. The system models critical basking habitats within the timber rattlesnakes mountain range in Virginia.
Basking habitats, which are very important to the snakes for thermal reasons, are usually open exposed areas where the pregnant females go to gestate and elevate their body temperatures during the summer. The basking habitats are also used by non-pregnant females and males that are shedding, digesting, mating, and healing from an injury or disease.
Garst starts with a set of known basking areas, and collects information for the known areas and for a set of random points.
In turn, this geographical information system computed a regression model over a 96 pixel demographic and calculated the probability of other potential sites that the snake would be prone to inhabit.
The information he collects include the variables of aspect, slope, landform index, elevation, and the percent forest cover within a radius of about 2,900 meters for the studied area.
With this data set he tested 22 combinations of variables listed above using logistic regression to see if the basking sites were different from random points across the study area and then ranked the model using Akaike’s Information Criterion, otherwise known as AIC.
The top ranking model was then applied back into the information system and a model map was generated that applied a probability of each pixel containing basking habitat to each pixel in the map.
As possible locations were computed, Garst would make expeditions to the area, checking for accuracy in the prediction.
Once the model was generated, Garst took it to Virginia's Goshen Wildlife Management Area to field test and proved successful by locating three basking areas there. This model will serve as a useful tool for helping Virginia Department of Game and Inland Fisheries biologists to conserve the timber rattlesnake in Virginia by allowing them to make the most of their field time when searching for the critical basking habitats.
Carola Haas, associate professor of wildlife ecology in the College of Natural Resources, oversaw the research as Garst’s adviser. Other important collaborators on this project include Stephen Prisley, Department of Forestry, and Dean Stauffer, Department of Fisheries and Wildlife Sciences.
Other scientists working with Garst included William Brown, of the State University of New York at Albany; Mike Pinder, Virginia Department of Game and Inland Fisheries; and William Martin, wildlife biologist.
As he completes his project, Garst, with his collective data, is working with the Virginia Department of Game and Inland Fisheries to come up with conservation recommendations. Garst explained: “Conservation is on the side of the timber since a large portion of its habitat remains in public lands that are less likely to be developed.”
The College of Natural Resources is involved in a variety of research and conservation efforts including
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