Collapse of South Africa’s penguins in the early 21st century

  • RJM Crawford
  • R Altwegg
  • BJ Barham
  • PJ Barham
  • JM Durant
  • BM Dyer
  • D Geldenhuys
  • AB Makhado
  • L Pichegru
  • PG Ryan
  • LG Underhill
  • L Upfold
  • J Visagie
  • LJ Waller
  • PA Whittington

Abstract

The number of African penguins Spheniscus demersus breeding in South Africa collapsed from about 56 000 pairs in 2001 to some 21 000 pairs in 2009, a loss of 35 000 pairs (>60%) in eight years. This reduced the global population to 26 000 pairs, when including Namibian breeders, and led to classification of the species as Endangered. In South Africa, penguins breed in two regions, the Western Cape and Algoa Bay (Eastern Cape), their breeding localities in these regions being separated by c. 600 km. Their main food is anchovy Engraulis encrasicolus and sardine Sardinops sagax, which are also the target of purse-seine fisheries. In Algoa Bay, numbers of African penguins halved from 21 000 pairs in 2001 to 10 000 pairs in 2003. In the Western Cape, numbers decreased from a mean of 35 000 pairs in 2001–2005 to 11 000 pairs in 2009. At Dassen Island, the annual survival rate of adult penguins decreased from 0.70 in 2002/2003 to 0.46 in 2006/2007; at Robben Island it decreased from 0.77 to 0.55 in the same period. In both the Western and Eastern Cape provinces, long-term trends in numbers of penguins breeding were significantly related to the combined biomass of anchovy and sardine off South Africa. However, recent decreases in the Western Cape were greater than expected given a continuing high abundance of anchovy. In this province, there was a south-east displacement of prey around 2000, which led to a mismatch in the distributions of prey and the western breeding localities of penguins.

Keywords: African penguin, diet, numbers breeding, numbers moulting, Spheniscus, survival

African Journal of Marine Science 2011, 33(1): 139–156

Author Biographies

RJM Crawford
Oceans and Coasts, Department of Environmental Affairs, Private Bag X2, Rogge Bay 8012, South Africa; Animal Demography Unit, University of Cape Town, Rondebosch 7701, South Africa; Marine Research Institute, University of Cape Town, Rondebosch 7701, South Africa
R Altwegg
Animal Demography Unit, University of Cape Town, Rondebosch 7701, South Africa; Marine Research Institute, University of Cape Town, Rondebosch 7701, South Africa; South African National Biodiversity Institute, Private Bag X7, Claremont 7735, South Africa
BJ Barham
Penguin Datasystems, 2 Cotham Place, Bristol, BS6 6QS, UK
PJ Barham
Animal Demography Unit, University of Cape Town, Rondebosch 7701, South Africa; Marine Research Institute, University of Cape Town, Rondebosch 7701, South Africa; HH Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
JM Durant
Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biology, University of Oslo, PO Box 1066, Blindern, 0316 Oslo, Norway
BM Dyer
Oceans and Coasts, Department of Environmental Affairs, Private Bag X2, Rogge Bay 8012, South Africa
D Geldenhuys
Cape Nature, Private Bag X29, Rondebosch 7701, South Africa
AB Makhado
Oceans and Coasts, Department of Environmental Affairs, Private Bag X2, Rogge Bay 8012, South Africa
L Pichegru
Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch 7701, South Africa
PG Ryan
Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch 7701, South Africa
LG Underhill
Animal Demography Unit, University of Cape Town, Rondebosch 7701, South Africa; Marine Research Institute, University of Cape Town, Rondebosch 7701, South Africa
L Upfold
Oceans and Coasts, Department of Environmental Affairs, Private Bag X2, Rogge Bay 8012, South Africa
J Visagie
Cape Nature, Private Bag X29, Rondebosch 7701, South Africa
LJ Waller
Animal Demography Unit, University of Cape Town, Rondebosch 7701, South Africa; Marine Research Institute, University of Cape Town, Rondebosch 7701, South Africa; Cape Nature, Private Bag X29, Rondebosch 7701, South Africa
PA Whittington
East London Museum, PO Box 11021, Southernwood 5213, South Africa; Department of Zoology, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031, South Africa
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Articles

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eISSN: 1814-2338
print ISSN: 1814-232X