The document discusses a study on the road avoidance behavior of garter snakes from populations in areas with high and low road densities. The researchers tested the snakes' responses to road scent versus forest scent or no scent in a three-way choice apparatus. For snakes from high road density areas, there was no preference between road scent and non-road scents, but they avoided the no-scent option. Snakes from low road density areas showed a trend of avoiding road scent compared to other scents. The results suggest snakes from areas with more roads are habituated to road smells while those from less developed areas avoid unfamiliar scents like roads.
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![Road avoidance behavior in animals is influenced by a variety of mechanisms and cues, including chemical, auditory, tactile, and thermal. In studying the relationship between chemical cues and behavior, snakes are valuable study organisms due to their reliance on chemosensory stimuli from their environment. The garter snake is an ideal organism for road ecology studies because of documented cases of high road mortality and the wide range of habitats the species occupies, many of which are in close proximity to roads. The purpose of this study was to identify possible differences in road avoidance behavior based on chemical cues in high and low road density populations of garter snakes. We hypothesized that garter snakes from high road density populations would show avoidance to road scent and garter snakes from low road density populations would not show avoidance to road scent. Olfactory cues as a mechanism for road avoidance behavior in garter snakes, Thamnophis sirtalis , from high and low road density populations Neil Dazet and Diana Mullich, Biology Department, Missouri State University Abstract Roads have become a prevalent feature within many ecosystems and impose several negative ecological impacts on local flora and fauna. Reptiles experience high road mortality rates as they participate in seasonal movements. Several species of snakes demonstrate road avoidance behavior; however, the exact cues that elicit this behavior are unknown. The garter snake, Thamnophis sirtalis , due to its wide distribution, high road mortality rates, and occurrence in areas of high road densities provides an opportunity to address the role of olfactory cues in road avoidance behavior. This study evaluated differences in road avoidance behavior based on olfactory cues in high and low road density populations of garter snakes. Snakes from high and low road density areas were tested once in a 3-way choice apparatus with road scent, forest scent, and distilled water. When choice frequencies were grouped by road scent and non-road scent, results were not significantly different from random. When choice frequencies were grouped by scent and no scent, data were significantly different from random; snakes from high road density populations were attracted to familiar scents. Further studies are necessary to understand the choices behind road avoidance behavior, especially in species threatened by the ecological impacts of roads. Introduction Methods Snake Collection Sites Methods, continued Results, continued Acknowledgments Snake Collecting : Mariah Carter, Ryan Combs, Christin Dzurick, Josh Flinn, Kristy Marson, Evan Menzel, Ed Mullich, Anna Scesny Statistics and Experimental Design : Dr. Alicia Mathis, Dr. John Havel Lab Space and Supplies : Dr. Brian Greene, Dr. Don Moll, Tina Tamme, Missouri State University Collecting Permit : Missouri Department of Conservation Discussion Snakes were tested in a 3-way choice apparatus consisting of a square acclimation chamber, PVC pipe branching in three directions, and rectangular scent chambers each containing 5 ml of one of three possible scents (road, forest, distilled water) held in a cotton ball. Road scent was obtained by pouring distilled water on a variety of road surfaces and then collecting the liquid with transfer pipettes. Forest scent was collected using the same method on the forest floor of the Springfield Nature Center. Snakes were tested in a random order, and each snake was tested only once. Scent order was also randomized for each trial. The snake’s decision was recorded when its entire body entered one of the three scent chambers. Results In order to obtain adequate expected values for all statistical analyses, choice frequency data were grouped by road scent versus non-road scent (forest and blank) and scent (road and forest) versus no scent (blank). When choice frequency data were grouped by road scent and non-road scent, the data were not significantly different from random (Chi-square = 3.0, n = 30, p = 0.392; Fig. 1). Figure 1 . Observed and expected choice frequencies for high and low road density individuals, with scents grouped as either road or non-road scents. When choice frequency data were grouped by scent and no scent, the data were significantly different from random (Chi-square = 8.33, n = 30, p = 0.04; Fig. 2). Figure 2 . Observed and expected choice frequencies for high and low road density individuals, with scents grouped as either scent or no scent. ,[object Object],[object Object],[object Object],[object Object],High Road Density Snakes (n = 18) Springfield (Greene Co.) Low Road Density Snakes (n = 12) Van Meter State Park (Saline Co.) Sedalia (Saline Co.) Washington State Park (Washington Co.) Wire Road Conservation Area (Stone Co.)](https://image.slidesharecdn.com/dazetmullichidf2007-111126091313-phpapp01/85/Olfactory-cues-as-a-mechanism-for-road-avoidance-behavior-in-garter-snakes-Thamnophis-sirtalis-from-high-and-low-road-density-populations-1-320.jpg)
