New guidance on hand-rearing decisions for endangered penguin chicks

African penguin chicks. Photo credit: SANCCOB.

SOUTH AFRICA – Researchers have developed a model to provide guidance on the likelihood of abandoned African penguin chicks surviving after they are admitted to rehabilitation.

Developed by researchers from the Universities of Bristol, Exeter and Cape Town, the Southern African Foundation for the Conservation of Coastal Birds (SANCCOB) and Bristol Zoological Society, it is the first model of its kind.

The use of rehabilitation for conservation is growing worldwide, with many research papers monitoring the success of individuals after their release. Rearing chicks that are unlikely to survive naturally could significantly contribute to the conservation of threatened bird species such as the African penguin.

Once an adult penguin begins to moult it is no longer waterproof, so can no longer feed its chick. A scarcity of prey leads to slow growth rates and can cause chicks not to fledge in time. The chicks are abandoned if the adults start to moult before the chick fledges.

Every year, abandoned African penguin chicks are hand-reared by SANCCOB and released back into the wild. Abandoned chicks would not survive without intervention.

Penguin chick being checked over. Photo credit: SANCCOB.

This 'chick bolstering project' is an important conservation action for these endangered birds. It aims to bolster the African penguin population while methods to establish new colonies near high prey abundance are developed.

Decisions of whether and when to remove animals from the wild rarely use quantitative criteria. Where such criteria are assessed, there have been few studies to investigate whether they effectively predict rehabilitation outcomes.

In this new study, published this month in Animal Conservation, researchers investigate whether a body condition index (mass correcting for structural size), other structural measurements and sex can predict rehabilitation outcome.

Joanne Morten from the University of Bristol's School of Biological Sciences, lead author of the research, said, "Using data from over 1,400 chicks rescued over six breeding seasons, we identified clear body condition thresholds that colony managers can use to prioritise the removal of chicks.

"These thresholds also allow the rehabilitators to rapidly identify individuals in need of critical attention."

African penguin colony managers are currently using the body condition index to guide removal. This study demonstrates its effectiveness, with only 2.3 percent of chicks admitted with a body condition index so low there was a less than 50 percent chance of survival.

Miss Morton said, "However, almost a third of chicks admitted may well have survived naturally. Hand-reared African penguin chicks are just as successful as their naturally-reared counterparts, but we don’t want to cause undue stress and use resources unnecessarily.

"The body condition thresholds identified in this study can be used to guide future management strategies, and can be rapidly incorporated.

"The body condition index uses mass and bill length, two measurements that are easy and quick, minimising handling stress.

"This is an extremely useful guide which, when used in conjunction with nest monitoring, can effectively identify chicks that have been abandoned. This tool could be useful, not just to the endangered African penguin, but other species where chicks can be successfully hand-reared."

Journal citation
Morten, J.M.,  Parsons, N.J., Schwitzer, C., Holderied, M.W. & Sherley, R.B. (2017). Body condition as a quantitative tool to guide hand-rearing decisions in an endangered seabird. Animal Conservation. doi: 10.1111/acv.12338

Source
New guidance on hand-rearing decisions for endangered penguin chicks [press release], 17 February 2017, University of Bristol