Consistently bolder turtles maintain higher body temperatures in the field but may experience greater predation risk
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Behavioral ecologists have assumed that animals will optimize behavior to match their current situation, yet studies reveal limited behavioral flexibility and extensive variation among individuals in their response to a similar stimulus. This phenomenon is referred to as “animal personality,” and recent efforts seek to determine the implications of personality for interactions with the biotic and abiotic environment. Doing so promises to illuminate how selection is operating on behavioral traits and, consequently, how stable, among-individual variation in behavioral types is maintained evolutionarily. We examined a natural population of forest-dwelling eastern box turtles (Terrapene carolina) to understand the effects of differences in levels of boldness on thermoregulatory behavior, injury history, and movement rates. Repeated behavioral trials revealed that individual turtles varied consistently and dramatically in boldness (latency to emerge from the shell or begin moving after handling and confinement). Behavioral differences were independent of phenotypic state or environmental conditions, suggesting the existence of personality in these turtles. Moreover, bolder turtles maintained higher body temperatures in the field and tended to have more damage to their shells, possibly indicative of more frequent predation attempts. Little work has been done on personality in terrestrial ectotherms, and this study enhances our understanding of this phenomenon by highlighting the potential trade-off between mortality and thermoregulation.
Animals often exhibit markedly different personality traits from each other. We sought to understand how personality traits affect interactions with the environment, and thus how natural selection may be acting upon and maintaining behavioral variation. We studied this in terrestrial ectotherms, box turtles, for whom the trade-off between basking and predation risk may be a significant factor. We found that individual turtles differed consistently in boldness (time spent hiding and immobile after handling) and that bolder turtles maintained higher body temperatures but tended to have more injuries on their shells. This suggests that being bold is beneficial for thermoregulation, which may enhance growth and fecundity, but could expose turtles to greater risk of predation. Variation in the expression of boldness may, therefore, serve to maintain behavioral variation in the population.
KeywordsPersonality Reptile Temperament Thermoregulation
B. Boles, T. Flock, S. Khoo, and W. Robinson provided essential assistance with fieldwork. The feedback of two anonymous reviewers greatly improved this manuscript. Financial support was provided by Wabash College, the Norman E. Treves Fund, and the Robert O. Petty Fund.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All applicable international, national, and institutional guidelines for the care and use of animals were followed. All procedures performed were in accordance with the ethical standards of the institution at which the studies were conducted. Approval was provided by the Wabash College Institutional Animal Care and Use Committee and by the Indiana Department of Natural Resources (Scientific Purposes License 15-136 and 16-154).
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