Consequences of individual removal on persistence of a protected population of long-lived turtles

Ecological and Fitness Correlates of Personality in a Long-lived Terrestrial Turtle

An individual's behavioral tendencies (i.e., personality or temperament) can influence its interactions with the environment and thus have important ecological and evolutionary consequences for animal populations. Boldness, defined as an individual's tendency to engage in risk-taking activities, is a phenotypically variable trait linked with numerous behavioral and fitness outcomes in free-ranging animals. We examined variation and repeatability of boldness and other behavioral characteristics in two wild Eastern Box Turtle (Terrapene carolina carolina) populations using radiotelemetry, and assessed fitness correlates of boldness over multiple years. We observed large amounts of among-individual variation and within-individual consistency (i.e., repeatability) of boldness as measured by their head emergence latency following a standardized confinement assay. Individuals were also consistent in several in-field behaviors including movement rate, home range size, and date of emergence from overwintering refuges. Individuals with shorter head emergence latencies (i.e., bolder turtles) had larger home ranges, emerged earlier from overwintering dormancy, and experienced moderately lower survival compared with shy individuals. Boldness did not affect time spent within the thermal preference range, somatic growth rates, or the frequency of mating or same-sex aggressive encounters. Boldness and its effects on in-field behaviors differed between sexes and populations, and the relationship between boldness and survival was temporally variable. Our results suggest possible intrinsic behavioral types in T. c. carolina and highlight the importance of long-term and multipopulation studies when examining ecological and evolutionary processes that shape personality phenotypes in turtles.

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.

Effects of Drought on Western Pond Turtle Survival and Movement Patterns

Drought has the ability to affect the persistence of small animal populations, especially those tied to aquatic habitats. We studied the response of western pond turtles Actinemys marmorata to California's worst drought on record. From 2009 through 2015 we used telemetry to track movements and assess survival of 19 western pond turtles in a stock pond at the San Joaquin Experimental Range in the western foothills of the Sierra Nevada, in Madera County, California. In 2013 the pond dried in late summer and winter rains were insufficient for pond formation. The pond remained dry through the end of the study in March 2015. In years with below average precipitation the pond often dried completely in late summer; however, the lack of a pond forming in winter and spring had not been previously documented. We observed no mortalities of radiotagged western pond turtles in years with normal precipitation. All observed mortalities occurred in drought years and in years when the pond completely dried up in the summer or never formed. Results from known-fate survival models revealed that survival decreased with increasing drought. Model results also indicated that male survival was slightly higher than female survival (19.1% vs. 11.5%), although the 95% confidence intervals overlapped. We observed high variability in western pond turtle movement distances from the pond in the final 2 y of the study. Two individuals that survived to the end of the study showed unique movement patterns. One young male moved frequently, accumulating a large total distance, moved into new areas, and eventually found his way into a livestock water trough. The other, a young female, moved 2.6 km from the pond (a minimum total distance traveled of 3.3 km based on telemetry locations) and emigrated to a pond on a neighboring ranch. Turtles that died exhibited no distinctive behaviors. After the pond dried western pond turtles remained terrestrial for long periods, with one surviving individual remaining out of water for 617 consecutive days, which is an unprecedented finding for this species to our knowledge. Our findings suggest that increased frequency and severity of droughts can affect the resiliency of small, isolated western pond turtle populations, especially those in ephemeral aquatic environments. These small populations are essential to the long-term survival of the species because of the current fragmented distribution of the species.