Individual differences in behavioral and physiological responses to stress should be considered in conservation programs for the Greater rhea

Abstract

Individual behavioral and physiological responses depend on each bird´s personality. Animal personalities influence population-level processes and result in relevant ecological interactions that can be important for wildlife management and conservation. Thus, some behavioral and physiological traits are better suited to captivity, reintroduction, and translocation. The Greater rhea (Rhea americana) is a flightless bird endemic to South America whose wild populations have drastically declined in many areas of their distribution. Captive breeding is an important conservation tool for this ratite, providing a source of individuals for repopulation. Previous studies involving conservation and management aspects have not considered the possible existence of individual differences in this species. Here we investigate individual variation in Greater rheas´ stress responses after a short transport by monitoring their behavior and measuring their fecal glucocorticoids metabolites. Our results indicate that glucocorticoid levels and behavioral responses to this acute stressor can vary markedly among individuals, suggesting the existence of proactive and reactive personalities. These traits have implications for releasing individuals in different environments, wild or captive, where distinct stressors are present. It would be appropriate to choose individuals with a personality that matches the better with the environment where they will be released. This information is relevant for promoting and preserving physiological and behavioral diversity in captive Greater rhea populations and taking into account the personality of these birds in management plans for its conservation.