Date of Award
Master of Science
Ecology, Evolution, and Organismal Biology
Ecology and Evolutionary Biology
Anne . Bronikowski
This thesis is an account of my research investigation of neonatal Thamnophis sirtalis habitat usage. This species is a highly adaptive and wide-ranging species across North America. They have been found in various habitats ranging from meadows and prairies to woodland edges and swamps. They can survive the bitter cold winters of Northern Canada and the metabolically taxing high elevations of the Rockies and Cascade mountains. To survive in the northern regions of North America, adult T. sirtalis are known to seek underground refuge called Hibernaculums. However, where neonates choose to overwinter has not been observed. The research presented here provide a possible method of how neonates locate overwintering sites in the first years.
In my first study, I establish that T. sirtalis used a pit in my study area with a combination of drift fencing and trail cameras. Over the course of the study, 90 events were photographed moving in and out of the pit. No neonates were photographed suggesting that either they were not present or did not utilize the same portions of the habitat. In my second study, I obtained thermal data for 3 habitat types: prairie, woodland edge, and woodlands for a 3-month period. The thermal data provided the monthly averages for each month but also showed the thermal variance between soil and elevated locations within each location. I was not able to quantify a thermal preference for T. sirtalis due to a lack of captures. The thermal variance suggests that the cover objects most likely did not provide a large enough thermal gradient that snakes prefer. My third study was the continuation of a long-term survey to determine the population size, growth rate, and survival probabilities. I was unsuccessful to achieve these goals due to a lack of recaptures. I believe this lack of recaptures could be remedied with the implementation of sampling methods like radio telemetry, drift fencing, pit fall traps, and funnel traps. In my final study, I demonstrated that neonates show a propensity to follow adult scent tracks that is statistically significant from chance for naïve neonates (P = 0.002) and repeated exposures to the apparatus (P = 0.0006). Neonates also demonstrated a statistically significant result for latency (P = 0.04) to complete the apparatus. Scent trailing could be the method that neonates use to locate hibernaculums in the first years of life. The results of the latency analysis suggest that the neonates learned the apparatus and made their choice quicker with each subsequent exposure.
Andersen, Jeremy, "Efforts in estimating habitat usage of neonatal garter snakes in central Iowa" (2019). Graduate Theses and Dissertations. 17637.