Comparison of moult phenology of African penguins Spheniscus demersus at Robben and Dassen islands
Abstract
Dassen and Robben islands are approximately 50 km apart, and currently support the largest and third largest populations of African penguins Spheniscus demersus respectively. At both islands, moult is the most synchronised and seasonal activity of the annual cycle. The main difference in moult phenology between the two islands is the degree of synchronisation. The peak moult period at Dassen Island is broader (less synchronous) than at Robben Island. At both islands, juvenile penguins moulted less synchronously than adults. Juvenile moult was less synchronous at Dassen Island than at Robben Island. Interannual variation in moult phenology was similar at Robben and Dassen islands. Island-level moult phenology was more synchronous in the year following the Treasure spill than was the case after the Apollo Sea spill. This was attributed to the larger number and proportion of birds that were affected by the Treasure spill. The temporal duration of the disruption to moult phenology was also greater following the Treasure spill, especially at Robben Island. Moult counts provide a relatively reliable method of estimating the size of the adult population at Robben Island, but not at Dassen Island where the large number of birds moulting away from the shoreline results in the population size being significantly underestimated. Although the number of active nest sites continued to increase up until 2004 at both islands, the numbers of adult moulters counted declined by 55% between 2003…
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The need to exploit a predictable food source during summer - not the fledging of chicks - appears to determine the timing of moult in African penguins.
“and the need to exploit a predictable food source during summer – not the fledging of chicks – appears to determine the timing of moult in African penguins [24], [49].”
From Hand-Rearing, Release and Survival of African Penguin Chicks Abandoned Before Independence by Moulting Parents (2014) · cites this paper as [49]
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- Authors
- Wolfaardt, A., Underhill, L., & Crawford, R.
- ORCID
- Crawford, RJM
- Venue
- African Journal of Marine Science
- Publisher
- Informa UK Limited
- Published
- 2009-04
- Volume
- 31
- Issue
- 1
- Pages
- 19-29
- ISSN
- 1814-232X (ISSN-L)
- 1814-2338
- OpenAlex
- W2038986302
- Cited by
- 11
- References
- 48
- Citations by year
- 2026: 1 · 2025: 1 · 2022: 1 · 2019: 1 · 2014: 2 · 2013: 1
- FWCI
- 0.88
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- African Journal of Marine Science (publishedVersion)
- Open University of Cape Town (University of Cape Town) (submittedVersion)
- Funders
- Earthwatch Institute
- Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
- Topics
- Physical Sciences › Environmental Science › Ecology › Avian ecology and behavior
- Physical Sciences › Environmental Science › Ecology › Marine animal studies overview
- Physical Sciences › Environmental Science › Ecology › Animal Ecology and Behavior Studies
- Keywords
- African penguin, Spheniscus demersus, moult phenology, interannual variability, oil spills, population size estimation, nest site availability, food availability, Robben Island, Dassen Island
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