Date of Graduation

5-2023

Document Type

Thesis

Degree Name

Master of Science in Biology (MS)

Degree Level

Graduate

Department

Biological Sciences

Advisor/Mentor

Beaupre, Steven J.

Committee Member

Douglas, Michael E.

Second Committee Member

Tullis, Jason A.

Keywords

Home Range; Rattlesnakes; Spatial Ecology

Abstract

Conservation of animal populations requires knowledge of their habitat and spatial needs. Quantifying spatial requirements involves the analysis of home range. We examined the effects of sex, body size (SVL), body condition (log mass/log SVL), and year on home range in Timber Rattlesnakes (Crotalus horridus) in Northwest Arkansas. Individual locality data from an ongoing, 22+ year radio-telemetry study in Madison Co., Arkansas were analyzed using both minimum convex polygon (MCP) and Kernel Density Estimates (KDE). Plots of the number of sequential observations versus home range (MCP and KDE) determined that a minimum of 25 locations per individual per active season (using weekly to bi-weekly sampling) were sufficient to generate a stable home range estimate using MCP and KDE methods. Restriction to samples of ≥25, resulted in 120 snake-years of data, distributed among 54 individuals (25 males and 29 females). Home ranges were estimated using ArcGIS 10.4 with HRT extension. Mixed model ANCOVA revealed a significant SVL by Sex interaction. Male MCP increased with body size, whereas, no effect of body size was detected for females. Improved body condition (log mass/log SVL) increased MCP and KDE (90% and 95%) in males, but not in females. Home range was compared within individuals among years (MANOVA). Significant annual differences in home range centroid were observed in 21 of 23 individuals with a minimum of three years of data. Our results verify that spatial needs of males and females differ, and importantly, suggest that home range frequently shifts in location among years. We support the notion that habitat use of C. horridus is highly variable and requires large sample size across seasonal and annual temporal scales to best inform conservation activities.

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