Overwintering behavior reduces mortality for a terrestrial turtle in forests managed with prescribed fire

Prescribed fire is an essential management practice in pyrogenic ecosystems, but fire can also be a significant disturbance and source of mortality for both target and non-target species. Seasonal periods of animal inactivity may provide opportunities to design burn plans that minimize negative impacts to species of conservation concern, but few studies have rigorously examined this possibility. Using radiotelemetry, we studied overwintering behavior and interactions with fire in a forest-dwelling terrestrial turtle, the Eastern Box Turtle (Terrapene carolina carolina), over an eight-year period at two sites that use prescribed fire in forest management. Turtles at both sites selected predominantly hardwood forests and mesic habitats and avoided upland pine forests. Turtles buried deepest (2.9 - 3.2 cm) below the soil-litter interface in late February and then moved gradually shallower until emergence in early April. Emergence timing varied over a 58-day period, but was consistent within individuals from year to year. Turtles also maintained fidelity to refuge locations, but those overwintering in burned areas selected sites over twice as far from refuges used in previous years compared to those in unburned areas. The areas and habitats selected by turtles during winter served as refugia from fire, and those whose refuges did burn remained buffered from lethal temperatures even at shallow burial depths. The only fire-related injury or mortality occurred during seasons of surface activity. Timing burning and other forest management practices during periods of winter dormancy may thus minimize threats to turtle populations, but modifications to prescribed fire regimes must also be balanced with other management objectives.

Variation and repeatability of home range in a forest-dwelling terrestrial turtle: implications for prescribed fire in forest management

Animal movements and use of space are in part determined by interactions between individual attributes such as sex and body size and extrinsic environmental factors such as the seasonal availability, quality and spatial configuration of resource patches in the landscape. Fire is a common and widespread disturbance process that has the potential to affect animal movements through modifications to the environment. Using radiotelemetry, we examined the contribution of these factors to variation in movements and home range over a 5-year period in a forest-dwelling terrestrial turtle, Terrapene carolina, at fire-maintained and unburned habitats in the southeastern United States. Female turtles had annual home-range sizes twice as large as males and moved longer distances per day during the nesting season (June and July), but males exhibited greater spatial fidelity from year to year. Turtles at the unburned site had home-range sizes twice as large as those at the fire-maintained site, and home-range size also decreased with increasing frequency and extent of fire, but this latter effect was strongest in females. Home-range behavior was highly repeatable within individuals of both sexes over time. This is the first evidence that fire influences the spatial ecology and movements of turtles, most likely through fire's impact on the spatial configuration, availability and quality of critical resources. That individuals behaved consistently through time, but differently from one another according to both intrinsic individual attributes and extrinsic environmental factors provides strong evidence of consistent inter- and intra-population variation in space use and movement behaviors in T. carolina. Such intra-specific behavioral variation suggests applying caution when extrapolating results to other sites across the geographic range of a species for use in conservation and management.

Responses of a forest-dwelling terrestrial turtle, Terrapene Carolina, to prescribed fire in a Longleaf Pine ecosystem

Prescribed fire is commonly used as a tool to meet a range of forest management goals. Owing to their limited movement abilities, terrestrial turtles are likely to be at high risk of injury and mortality, and to experience other fitness consequences with population-level implications from fire. Using radiotelemetry, we studied the responses of Eastern Box Turtles, Terrapene carolina carolina, to prescribed fire management in a sandhills Longleaf Pine forest system over a five-year period and compared our results to a nearby population in an unburned coastal plain location. Individual variation in turtle survival was strongly dependent on how frequently and extensively the areas were burned, with annual survival rates of 94.5% in unburned areas decreasing to 45.9 % in the most extensively burned areas. Turtles at the fire-maintained sandhills site had annual survival rates 4.9 % less than at the unburned coastal plain site, and females had annual survival rates 6.8 % less than males. Survival varied seasonally, with greatest mortality rates in winter and spring, especially among females. Growth rates and body condition did not differ between sites, nor did they vary according to fire extent and frequency at the fire-maintained site. Although mortality was greater and spatially variable at the fire-maintained site, annual survival rates across the site (86 - 90 % for females and males, respectively) were comparable to other stable populations of T. carolina. The lesser than expected mortality rate at the fire-maintained site was likely the result of turtles' strong selection of mesic hardwood forests near bottomlands and streams - habitats that may serve as refugia from fire. In areas where T. carolina conservation is a priority, land managers should integrate maintenance of fire refuge habitats into burn planning to minimize unintended negative impacts to this imperiled species.