Fat chance? Endangered penguin rehabilitation has mixed conservation outcomes

Abstract

Abstract Rehabilitation of sick or injured wildlife supports wild populations of threatened species by improving the health of individuals. Post‐release assessment of the efficacy of rehabilitation relies on re‐sighting and identification of both rehabilitated and comparable wild individuals. For species or age classes with naturally low survival rates and re‐sighting probabilities, evaluating the long‐term success of rehabilitation is challenging. We use a rehabilitation database in conjunction with a long‐term monitoring database to determine rehabilitation outcomes for yellow‐eyed penguin (Megadyptes antipodes) chicks across 10 breeding seasons. Although rehabilitated chicks fledged at a higher mass, their post‐fledging survival probability was lower (0.23 ± 0.10—0.47 95% CI) than that of healthy (>5 kg) wild‐fledging conspecifics (0.38 ± 0.26—0.51 95% CI), or even of underweight (<5 kg) chicks fledging naturally (0.28 ± 0.11—0.53 95% CI). Removing underweight chicks for rehabilitation did not improve parent survival to the following season nor did it influence future breeding propensity; c. 100% of parents subsequently attempted to breed regardless of previous breeding outcome or interventions. Most wildlife rehabilitation programmes assume that efforts are improving the conservation status of the species, but longer‐term implications must be tested to ensure that scarce resources are expended on the best possible conservation outcomes.

Keywords

• fledgling mass
• penguin
• rehabilitation
• survival