Transport and release procedures in reintroduction programs: stress and survival in grey partridges

• Published in: Animal conservation 2015-02, Vol.18 (1), p.62-72
• Main Authors: Jenni, L., Keller, N., Almasi, B., Duplain, J., Homberger, B., Lanz, M., Korner-Nievergelt, F., Schaub, M., Jenni-Eiermann, S.
• Format: Article
• Language: English
• Subjects: corticosterone; glucocorticoids; grey partridge; reintroduction; release procedure; Stress; Stress response; survival; translocation
• ISSN: 1367-9430; 1469-1795
• DOI: 10.1111/acv.12136

During translocations, stress, as measured by the increase of glucocorticoids, cannot be avoided, but has been suspected to exacerbate the vulnerability to many causes of mortality after release. Therefore, measures to reduce stress have been proposed, such as keeping animals in pens before release (soft release). In this study, we investigated two open questions in translocations: (1) whether stress caused by the translocation procedure has an effect on survival; (2) whether soft release allows recovering from stress induced by capture and transportation. Hand‐raised grey partridges showed a moderate adrenocortical response to transportation and kept the capacity to mount a stress response to a new acute stressor, partly by a decrease of corticosteroid‐binding globulin capacity. In contrast to studies demonstrating a pervasive effect of capture and transport by virtual elimination of a proper stress response, we demonstrated a robust stress response and a return of baseline levels to pre‐transport levels after 33 h of acclimatization. Possibly captive‐bred birds may be less sensitive to capture and transportation than wild‐caught birds. During the first month after release, birds held 33 h in release pens survived better when their corticosterone levels were lower. However, survival beyond the first month did not differ between birds held 9 or 33 h in acclimatization pens. Elevated glucocorticoids, as induced by the translocation procedure, likely affect short‐term survival after release. We recommend glucocorticoid stress levels be surveyed in an appropriate subsample and minimized during translocations.