Biology Ph.D. Dissertations

Reptilian Activity, Movements and Spatial Ecology within the Oak Openings Region

Date of Award

2020

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Biological Sciences

First Advisor

Karen Root (Advisor)

Second Advisor

Michael Decker (Other)

Third Advisor

Kevin McCluney (Committee Member)

Fourth Advisor

Helen Michaels (Committee Member)

Fifth Advisor

Enrique Gomezdelcampo (Committee Member)

Abstract

Many taxa suffer from habitat loss, spread of invasive species, and climate change; however, reptiles are especially vulnerable because they are constrained physiologically from their ectothermic nature in addition to global population declines. Like other taxa, reptilian basic ecology requirements are influenced by ecological neighborhoods, which shape the abundance of critical resources and their movement patterns. My goal was to better understand reptilian movement patterns across spatial and temporal scales to facilitate conservation efforts within Oak Openings Region (OOR), of northwestern Ohio and southeastern Michigan, using a combination of field surveys, remote sensing data and modeling. My research examined (1) climate change, (2) distribution patterns, (3) habitat use, and (4) movement patterns. At the regional scale, we found moderate increases in suitable habitat for box turtles within the future scenarios based on climatic suitability models. Individuals may be more displaced or vulnerable from temperature change during the driest quarter of the year. Dispersal is feasible; box turtles, based on tracking of individuals, can move large distances within their lifetime but the physical barriers, like roads, on the landscape may greatly hinder these movements. I modeled habitat suitability for a suite of reptiles based on occupancy data and climate, habitat, elevation, and structural features. Currently, suitable habitat was less than half the area within OOR and was more restricted for two species of concern. There is a need to examine the range of limitations, i.e., minimum and maximum models, when planning conservation efforts for a suite of species, especially emphasizing the protection of wet and dry forest. At the local scale, I found using radio telemetry that box turtles displayed typical average home range sizes; however, some were much larger than other studies. This is likely a difference in landscape heterogeneity where home range size increased with greater shape complexity and decreased as it became more physical connected. Movements within preferred patch types may be more costly resulting in larger home ranges. Fine-scale tracking for box turtles and garter snakes was conducted using fluorescent powder. I found that they responded differently to the local environment as seen by trail curvature and distance traveled and were distinct from those found in other studies. Multi-species approaches are critical for conservation efforts. Combining field data with spatial modeling provides a dynamic tool for land management and informing conservation decisions.

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