Solar Farm Development Impacts on Eastern Box Turtle (Terrapene carolina) Home Ranges
Eastern Box Turtle (Terrapene carolina) populations have declined drastically since 1970 because of continued destruction and fragmentation of their habitat. Although they are known to shift their home ranges because of environmental degradation, it is unknown how solar arrays impact Eastern Box Turtles. From 2011–2018, we collected data on Eastern Box Turtle movement and occupancy in a 79-ha solar farm. The solar farm is divided into six fenced areas, each containing wildlife openings for movement of terrestrial fauna every 23 m around the fenced solar arrays. We hypothesized that the solar arrays changed the home range sizes of turtles that interacted with the field. We fitted 41 Eastern Box Turtles with radio transmitters and tracked their locations twice per week in June–August from 2011–2018. Seventeen turtles had home ranges that overlapped with the solar arrays whereas 24 turtles had home ranges that never interacted with the solar arrays. We calculated home range sizes and tested for differences between overlapping and nonoverlapping groups. We further considered if the number of observations within the solar farm impacted home range size and displacement. We found that Eastern Box Turtles that used the solar farm exhibited 55–83% larger home ranges on average than turtles in natural habitats, but there was no significant association of home range size with the amount of time observed within the solar farm. Finally, we discuss strategies to mitigate negative impacts of solar farm development on turtles.ABSTRACT
Map of Brookhaven National Laboratory. Colored outlined polygons are 95% minimum convex polygons for all Eastern Box Turtles monitored in 2012.
Tracking duration and time lag between observations for each Eastern Box Turtle. Tracking conducted between November and April was done to verify that turtles were overwintering.
Density plots (top) and scatter plot (bottom) of Eastern Box Turtle yearly home range sizes within and outside of the Brookhaven National Laboratory solar farm. Home ranges were estimated as (A) minimum convex polygons and (B) 95% kernel utilization distributions. Individual points represent turtles' home ranges for a given tracking year. Mean bootstrap group values are displayed as solid red lines and 95% bootstrap confidence intervals as dotted red lines. Mean values and confidence intervals are based on marginal values from a mixed effects model accounting for individual turtles as random intercepts.
Home range size, estimated as (A) minimum convex polygons and (B) 95% kernel utilization distributions as a function of the proportion of annual observations of box turtles within Brookhaven National Laboratory solar farm. Lines represent marginal estimates from mixed effect models accounting for individual turtles as random intercepts. Points represent conditional residuals.
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