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

Abstract

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.

State‐wide population characteristics and long‐term trends for eastern box turtles in North Carolina

“…As expected, turtles in this study were not confined to study area boundaries, with an emigration rate estimated by radiotelemetry of 9.4%. Apparent annual survival estimates from the overall model ranged from 85% to 86% for the various demographic groups, which after adjusting for emigration increases true survival estimates to 94.4–95.4%, values toward the higher end of the range of T. carolina populations elsewhere (81.3–96.3%; Dodd et al 2006, Nazdrowicz et al 2008, Currylow et al 2011, Roe et al 2019). Likewise, mean annual survival for the three ecoregions adjusted for emigration ranged from 88.2% to 96.3%.…”

“…Terrapene carolina carolina populations often maintain close associations with aquatic environments such as bottomlands, wetlands, streams, and nearby mesic forests (Rossell et al 2006, Rittenhouse et al 2008, West and Klukowski 2016, Roe et al 2018). Wetland habitats may be especially important during drought (Donaldson and Echternacht 2005), for refuge from fire (Platt et al 2010, Roe et al 2018, 2019), and for smaller individuals and early life stages (Jennings 2007, Roe et al 2018). Terrapene carolina carolina would benefit from a complementary approach to habitat conservation, where management practices are directed at maintaining wet areas in close proximity to terrestrial forests to support higher population densities.…”

“…It should be noted that commercial or incidental collection would have the same effect as mortality given that collected individuals are permanently removed from the population. Prior to this study, direct estimates of T. c. carolina survival were restricted to only a few populations, with values of 81.3–97.7% for four populations in Delaware (Nazdrowicz et al 2008), 85.8–91.3% for two populations in North Carolina (Roe et al 2019), and 96.3% for a population in Indiana (Currylow et al 2011). Annual survival in a closely related subspecies, T. c. bauri , was 87–89% in a Florida population (Dodd et al 2006).…”

“…While overall survival estimates are informative, understanding and projecting population trends can improve with more detailed estimates of size‐, age‐, and sex‐specific resolution on survival probabilities (Congdon et al 1993, 1994), yet prior to this study, such demographic information was largely lacking for T. c. carolina . Most estimates of survivorship in T. c. carolina are for adult and subadult individuals over a limited body size range (Nazdrowicz et al 2008, Currylow et al 2011, Roe et al 2019). In this study, survival differences among demographic groups (immature, adult male, adult female) were small and inconsistent.…”

Longleaf pine proximity effects on air temperatures and hardwood top-kill from prescribed fire

“…Hardwoods, particularly mesic oaks, develop cavities that are utilized by bats and snakes (Howze et al 2019). Small clumps of hardwoods may have value as thermal or fire-free refuges for organisms of limited mobility (Neel and McBrayer 2018;Roe et al 2019). The ecological value of individual or small groups of hardwoods in a longleaf pine matrix, as opposed to the deleterious effect of mass hardwood recruitment from fire exclusion, implies the need for information on selective control of hardwoods using prescribed fire.…”