Body condition as a quantitative tool to guide hand‐rearing decisions in an endangered seabird

• Published in: Animal conservation Vol. 20; no. 5; pp. 471 - 479
• Main Authors: Morten, J. M., Parsons, N. J., Schwitzer, C., Holderied, M. W., Sherley, R. B.
• Format: Journal Article
• Language: English
• Published: London Wiley Subscription Services, Inc 01.10.2017
• Subjects: Adaptive management; Adults; African penguin; Aquatic birds; Body condition; body condition index; Chicks; Colonies; Confidence intervals; Conservation; Endangered & extinct species; Endangered species; Growth rate; Hand tools; Hand‐rearing; Individual rearing; Juveniles; Mathematical models; Molting; Moulting; Rare species; Rehabilitation; Reinforcement; Removal; Resource management; Resources; Seabird conservation; Seabirds; Spheniscus demersus; Survival; Wildlife; Wildlife conservation; Wildlife management; Wildlife rehabilitation
• ISSN: 1367-9430; 1469-1795
• DOI: 10.1111/acv.12338

The use of wildlife rehabilitation for conservation is growing, but quantitative criteria are rarely used to guide whether and when to remove animals from the wild. Since 2006, large numbers of African penguin Spheniscus demersus chicks have been abandoned annually when adults enter moult with dependent young still in the nest. As part of conservation initiatives for this endangered species, these chicks were collected and hand reared to fledging age. Post‐release survival has been well documented; in this study we develop models to predict survival of individuals during rehabilitation with the aim of improving hand‐rearing success and guiding the use of scarce resources. For 1455 chicks abandoned between 2008 and 2013, we assessed whether a chick body condition index (BCI) could predict outcome (death or release) and time spent in rearing. In addition, for a subset of 173 chicks in 2012, we assessed whether BCI at admission influenced chick growth rates during rehabilitation and examined whether the use of additional structural measurements and sex provided additional power to predict outcome. Models predicted an 82.9% (95% confidence interval: 73.3–89.5%) release rate for chicks admitted with a BCI >0, the proposed guideline for removal from colonies. This fell below 50% for BCIs < −1.05; 66% of chicks were admitted with BCIs between these thresholds. Adding bill length to BCI improved the relative model fit, but in both cases only ~70% of rehabilitation outcomes were correctly predicted. Chicks that grew more quickly were more likely to be released and, for those that were released, had lower BCI at admission suggesting compensatory growth. Chicks were generally removed at an appropriate time to ensure successful hand‐rearing. However, 32% were admitted in good condition, highlighting the importance of using adaptive management to guide wildlife rehabilitation and the allocation of conservation resources. Wildlife rehabilitation for conservation is growing, but few quantitative criteria exist to guide removal of animals from the wild. To reinforce declining populations, endangered African penguin Spheniscus demersus chicks abandoned when prey is scarce are collected and hand reared to fledging. Using data from 1455 chicks, we assessed whether body condition and other structural measurements could predict release rates. Our results identify clear body condition thresholds that colony managers can use to prioritize removal of chicks and allow rehabilitators to rapidly identify animals needing critical attention. Most chicks were removed at an appropriate time, but 32% were admitted in good condition and may still have faired well in the wild, highlighting the value of using quantitative tools in wildlife rehabilitation.