Movement and Habitat Selection of Eastern Milksnakes (Lampropeltis triangulum) at Intact and Fragmented Sites
Habitat loss and fragmentation are among the greatest threats to wildlife and biodiversity. Reptiles are particularly susceptible to these threats due to high site fidelity, large home ranges, and slow movement rates. To understand behavioral responses of Eastern Milksnakes (Lampropeltis triangulum) to fragmentation, we compared home range size and movement rates between a fragmented habitat and an intact habitat. Additionally, we quantified road avoidance and habitat selection in the fragmented habitat. In 2015 and 2016, we collected 453 locations from 17 individuals from Rouge National Urban Park (RNUP), the fragmented study area, using radio-telemetry. We compared our results to a previous study with 1,001 locations from 30 individuals at Queen's University Biological Station (QUBS), our intact study area, collected from 2003 to 2004. We found that home ranges were smaller, but daily movement rate (DMD) and distance-per-move (DPM) were greater in the fragmented study area. We also observed that road crossings by snakes occurred less than expected, suggesting active avoidance of roads. Milksnakes in the fragmented habitat selected locations with a greater number of cover objects within open patches surrounded by high density vegetation, which is consistent with previous findings from the intact habitat. Our findings suggest that Eastern Milksnakes benefit from heterogeneous microhabitats and an abundance of available anthropogenic or natural cover.
Box plots showing differences in home range sizes and movements of Eastern Milksnakes (Lampropeltis triangulum) at Rouge National Urban Park (RNUP) and Queen's University Biological Station (QUBS). Home range size was estimated as 95% minimum convex polygons (MCPs), and movements are represented by distance moved per day (DMD; m/day) and distance per move (DPM; m). Gray points overlayed on boxplots represent the raw data. Horizontal lines in boxplots represent the median, outer edges of the boxes represent the 25th and 75th percentile of the data, respectively, whiskers extend from the edge of the box to the maximum and minimum values up to 1.5x the interquartile range, and points plotted beyond whiskers are outliers.
Standardized coefficients and 85% confidence intervals of the top model for habitat selection by Eastern Milksnakes (Lampropeltis triangulum) at Rouge National Urban Park (RNUP). Coefficients greater than 0 (horizontal dashed line) indicate selection and coefficients less than 0 indicate avoidance for each respective variable. Definitions and full names of each variable used in modeling can be found in Table 2.
Contributor Notes
Associate Editor: J. D. Litzgus.