Page 165 - Atlas Sea Birds Ver1

2.2.4.4 Breeding sites of seabirds from south of the West Coast
National Park to Paarl

Authors: JL Visagie, L Upfold, RJM Crawford, BM Dyer, M Masotla, M van Onselen, and AB Makhado

Abstract:
Twelve seabird species have bred at eight localities in South Africa from south of the West Coast National Park to Paarl Waste Water
Treatment works. They are: African Penguin (Spheniscus demersus), Leach’s Storm Petrel (Hydrobates leucorous or Oceanodroma
leucorhoa), Great White Pelican (Pelecanus onocrotalus), Cape Cormorant (Phalacrocorax capensis), Bank Cormorant (P. neglectus),
White-breasted Cormorant (P. lucidus), Crowned Cormorant (Microcarbo coronatus), Kelp Gull (Larus dominicanus), Hartlaub’s Gull
(Chroicocephalus hartlaubii), Grey-headed Gull (C. cirrocephalus), Greater Crested Tern (Thalasseus bergii) and Caspian Tern (Hydro-
progne caspia). The region includes Dassen Island, which was the centre of unsustainable harvesting of African Penguin eggs. Numbers
of adult-plumaged penguins at Dassen Island decreased by 90% from c. 1.45 million in 1910 to c. 0.14 million in 1967, when collections
of eggs ceased. Subsequent trends in penguins were driven by food availability, a decrease of which in the 21st century led to only 2,500
pairs breeding at the island in 2022. There were long-term decreases in numbers of Cape and Bank cormorants at Dassen Island, which
were also attributed to decreased food availability. Great White Pelicans and Leach’s Storm Petrel colonised Dassen Island in c. 1955 and
1997, respectively. Pelicans fed on the chicks of several seabird species at the island and likely contributed to a decrease in numbers of
Kelp Gulls breeding there. Farther south the Koeberg Nuclear Power Station provided additional breeding space for six seabird species.

Introduction:
Twelve seabird species have bred along west South Africa from south of the West Coast National Park to Paarl Waste Water Treatment
works. They are: African Penguin (Spheniscus demersus), Leach’s Storm Petrel (Hydrobates leucorous or Oceanodroma leucorhoa),
Great White Pelican (Pelecanus onocrotalus), Cape Cormorant (Phalacrocorax capensis), Bank Cormorant (P. neglectus), White-breasted
Cormorant (P. lucidus), Crowned Cormorant (Microcarbo coronatus), Kelp Gull (Larus dominicanus), Hartlaub’s Gull (Chroicocephalus
hartlaubii), Grey-headed Gull (C. cirrocephalus), Greater Crested Tern (Thalasseus bergii) and Caspian Tern (Hydroprogne caspia).
The breeding took place at eight localities, which are shown in Figure 1 and briefly described below. For each locality, records of breed-
ing by the different species were collated for all years having information. When multiple counts were obtained for a species in a given
year, the maximum was shown on the relevant table. ‘√’ signifies that breeding occurred at a locality but the numbers were not ascertained;
‘?’ that breeding may have taken place. A short summary of methods used to obtain the estimates of numbers breeding is given in the
chapter ‘Introduction to Seabird Breeding Localities’.
In 1998, Dassen Island was considered a globally Important Bird Area. In addition to its seabirds, it then held c. 5% of the overall popu-
lation of African Black Oystercatcher (Haematopus moquini) (Barnes 1998).

Sources of information for species and numbers
breeding: The estimates of numbers of seabirds breed-
ing at the eight localities were from the following sources:
African Penguin (Frost et al. 1976, Shelton et al. 1984,
Crawford et al. 1995b, 2007b, 2011, 2013a, Sherley et al.
2020); Leach’s Storm Petrel (Underhill et al. 2002, Craw-
ford et al. 2007c); Great White Pelican (Crawford et al.
1995a), Cape Cormorant (Cooper et al. 1982, Crawford et
al. 2007a, 2016); Bank Cormorant (Cooper 1981, Crawford
et al. 1999, 2008, 2015, Crawford 2007); White-breasted
Cormorant (Brooke et al. 1982, Crawford 2007, Crawford
et al. 2013b); Crowned Cormorant (Crawford et al. 1982b,
2012, Crawford 2007); Kelp Gull (Crawford et al. 1982a,
2009, Whittington et al. 2016); Hartlaub’s Gull (Williams
et al. 1990, Crawford and Underhill 2003, Crawford et al.
2007c); Grey-headed Gull (Brooke et al. 1999, McInnes Die Skeiding (photo L Upfold)
and Allan 2011); Greater Crested Tern (Cooper et al. 1990,
Crawford 2009) and Caspian Tern (Cooper et al. 1992). Details of numbers of pairs in different years are given on
These observations were updated by unpublished records the following table. The Caspian Tern nest observed on 4
of South Africa’s Department of Forestry, Fisheries and the November 2014 had one egg.
Environment (DFFE).

Die Skeiding Year Kelp Caspian Tern
Coordinates: 33.3201 S, 18.1867 E Gull
Description: A pan to the north of Yzerfontein that is suf-
ficiently flooded in some years to form islets where birds 1981 3
may breed. 2013 68 0
Conservation status: It is not protected. 2014 118 1
Species and numbers breeding: Up to 118 pairs of Kelp 2016 80 0
Gull and one Caspian Tern pair have nested at the site. 2018 0 0

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