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Cited by 64Avian ecology and behaviorMarine animal studies overviewAnimal Ecology and Behavior Studies

Trends of African penguin Spheniscus demersus populations in the 20th century

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Crawford, R. J. M., Williams, A. J., Hofmeyr, J. H., Klages, N. T. W., Randall, R. M., Cooper, J., Dyer, B. M., Chesselet, Y.·1995·South African Journal of Marine Science
DOI 10.2989/025776195784156403
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Abstract

The entire nesting population of African penguins Spheniscus demersus was about 575 000 adults at the start of the 20th century. Numbers halved by the 1950s and continued to fall to about 220 000 by the late 1970s and about 180 000 by the early 1990s. In Namibia, there has been a 30% reduction since the late 1970s, the most severe declines being in the south, where colonies continue to decrease. Populations at Mercury, lchaboe and Halifax islands now appear to be stable. In South Africa, numbers fell by 17% between the late 1970s and early 1990s, with especially severe decreases near Saldanha Bay and at Dassen and Dyer islands. These decreases have been arrested, except at Dyer Island. Three new colonies were established in the Western Cape in the early 1980s and supported about 10 000 adult birds in 1994. At islands in Algoa Bay, numbers of adults increased by nearly 30 000 between the late 1970s and the early 1990s, with large increases at St Croix and Bird islands. Ongoing deterioration in the status of the species is being driven by the trends at Dyer Island and off southern Namibia, the causes of which must be investigated.

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  • In the Western Cape, penguins breed from February to September and predominately moult between September and January, once chicks have fledged.

    “In the Western Cape, penguins breed from February to September [23] and predominately moult between September and January, once chicks have fledged [24].”

    From Hand-Rearing, Release and Survival of African Penguin Chicks Abandoned Before Independence by Moulting Parents (2014) · cites this paper as [23]

    Citation [24] is attached to the moulting claim, not the February–September breeding claim. The section “Seasonal pattern of breeding off western South Africa” (page unavailable) says most birds at Robben Island moult in December, supporting a peak within the stated period. It does not establish a September–January moulting period across the Western Cape or say that moulting occurs once chicks have fledged. (LLM, conf=0.84)

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Cites

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Research works printed but not linked: 15

  1. BERRUTI. A. 1986 -The predatory impact of feral cats Felis catliS and their control on Dassen Island. S. Afr. J. Antarcl. Res. 16(3): 123-127.
  2. CRAWFORD, R. J. M. and H. G. v. D. BOONSTRA 1994- Counts of moulting and breeding jackass penguins Sphenisclis demerslI.I' -a comparison at Robben Island, 1988-[993. Mal'. Omitlwl. 22(2): 213-219.
  3. CRAWFORD. R. J. M .• BOONSTRA. H. G. v. D., DYER, B. M. and L. UPFOLD 1995b -Recolonization of Robben Island by African penguins. 1983-1992. In Tile Penguin.
  4. CRAWFORD. R. J. M., DYER. B. M. and R. K. BROOKE 19'14 -Breeding nomadism in southern African seabirds -con- straints, causes and conservation. Ostrich 65(2): 231-246.
  5. CRAWFORD. R. J. M. and P. A. SHELTON 1981 -Population trends for some southern African seabirds related to fish availability. In Proceedings (!t'the Symposium on Birds of the Sea and Shore. 1979.
  6. Cooper. J. (Ed.). Cape Town: African Seabird Group: 15-41.
  7. CRAWFORD. R.'J. M .. WILLIAMS. A. 1.. RANDALL. R. M .. RANDALL. B. M., BERRUTI. A. and G. J. B. ROSS 1990 -Recent population trends of jackass penguins Sphen;scus demersus off southern Africa. BioI. Con.I'£"T. 52(3): 229-243.
  8. DUFFY, D. C. BERRUTI. A., RANDALL, R. M. and J. COOPER 1984 -Effects of the 1982-3 warm water event on the breeding of South African seabirds. S. A.ti: .I. Sci. 80(2): 65-69.
  9. FROST. P. G. H., SIEGFRIED. W. R. and J. COOPER 1976- Conservation of the jackass penguin (Sl'heniscus demersus (L)). Bioi. Com-en'. 9(2): 79-99.
  10. HOCKEY. P. A. R. and J. HALLINAN 1981 -Effect of human disturbance on the breeding behaviour of jackass penguins SphenisClIs demer.HIS. S. Afr. .I. Wilel/. Res. 11(2): 59-62.
  11. LOUTIT. R. and D. BOYER 1985 -Mainland breeding by jack- ass penguins SphenisClIs demerslIs in South West Africa/ Namibia. Cormorant 13(1): 27-30.
  12. RANDALL, R. [M.I and B. [M.I RANDALL 1986 -The Kapodistrias affair -another oiling incident affecting sea- birds. 80kmakierie 38(2): 37-40.
  13. RANDALL, R. M., RANDALL, B. M., COOPER, J., LA COCK, G. D. and G. J. B. ROSS 1987 -Jackass penguin Spheniscl/s demersl/s movements, inter-island visits, and settlement. .I. Fld 01'11.58(4): 445-455.
  14. SHAUGHNESSY, P. D. 1980 -Influence of Cape fur seals on jackass penguin numbers at Sinclair Island. S. Afr . .I. Wifd/. Res. ]0(1): 18-21.
  15. VAN TONDER, M. W. P. 1990 -Onlangse sensusse op die Kaapse brilpikkewyn. SphenisClls demersl/s te Boulders- strand vir die proklamering van 'n pikkewynreservaal. Nature Conservation Diploma dissertation, Cape Techni- kon: 22 pp.

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Authors
Crawford, R. J. M., Williams, A. J., Hofmeyr, J. H., Klages, N. T. W., Randall, R. M., Cooper, J., Dyer, B. M., & Chesselet, Y.
ORCID
Venue
South African Journal of Marine Science
Publisher
National Inquiry Services Center (NISC)
Published
1995-12
Volume
16
Issue
1
Pages
101-118
ISSN
0257-7615 (ISSN-L)
DOI
10.2989/025776195784156403
OpenAlex
W2088224522
Cited by
63
References
0
Citations by year
2024: 2 · 2022: 3 · 2021: 1 · 2020: 1 · 2019: 1 · 2018: 2 · 2017: 1 · 2016: 1 · 2015: 2 · 2014: 7 · 2013: 2 · 2012: 3
FWCI
1.72
Type
journal article
Language
en
Open access
Locations
South African Journal of Marine Science (publishedVersion)
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, population decline (ecology), population trends, seabird colonies, nesting population, Algoa Bay, conservation status

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