Stress response assessment during translocation of captive breed Greater Rheas into the wild

LÉCHE ALVINA; VERA CORTEZ, M; DELLA COSTA, N.; NAVARRO, J.L:; MARIN, R. H.; MARTELLA, M.B.

Journal of Ornithology

Springer

Año: 2016 vol. 157 p. 599 - 607

2193-7206

Translocation is an extensively used conservation tool that involves animals´ exposure to stressful situations that may influence the post release survival. In this study, 20 Greater Rheas (Rhea americana) adults hatched and reared in captivity were translocated to a wildlife refuge. After transport and before release, animals were kept in pens at the liberation site to make a "soft-release" strategy. Fecal glucocorticoid metabolites (FGM) were monitored during Pre-transportation, Post-transportation and Pre-release, and Post-release phases as an indicator of the stress of translocation and acclimation to the new environment. During Pre transportation phase, FGM levels found were consistent with the baseline concentrations described for this species for males and females, respectively. On Day 1 after transportation, FGM levels were increased in both sexes returning to baseline values during the maintenance in the pens. Although the handling and transportation triggered an acute stress response, the41 procedures utilized and the soft release in pens allowed rheas to quickly reestablish baseline FGM levels.After release into the novel wildlife refuge, FGM levels were increased again and remained similarly increased during the following two month of the study. Findings suggest a strong chronic stress response, probably triggered by a combination of many factors (i.e. novelty, attacks from predators, social interactions, human related disturbances such as poaching, vehicular noise, hunting dogs) that may reduce the bird´s ability to solve new challenging situations, especially the illegal hunting pressure that seems to be a significant threat in this species.