Page 401 - Atlas Sea Birds Ver1

Kemper et al. (2007) considered that 2,126 pairs bred in Conservation
the same region, with an additional 60 pairs at Ilha dos
Tigres in southern Angola. From 2008–2012, Crawford Twenty-eight sites held > 1% of the most recent estimate
et al. (2013) estimated that 1,542 pairs bred around the of the coastal population of White-breasted Cormorants
entire coast of South Africa. From 2018–2022, the sum of between Luanda in Angola and South Africa’s border with
maxima recorded at coastal sites between north Namibia Mozambique (Table 2). Three were in Angola: Ilha Sao João
and South Africa’s border with Mozambique was 1,627 pairs da Cazanga, Ilha dos Pássaros, and Ilha dos Tigres. Eight
(Table 2). were in Namibia: MÖwe Bay, Die Oase, Huab River lagoon,
The sum of the most recent estimates made at all colonies 10 km south of Toscanini, Mile 4 Saltworks, Seal and Pen-
between Luanda and South Africa’s border with Mozam- guin islands, and Southern Mining Pond S4, although more
bique was 1,825 pairs, of which 210 were in Angola, 535 recent information is needed to confirm the status of MÖwe
in Namibia and 1,105 in South Africa (Table 2). The sums Bay, Die Oase, 10 km south of Toscanini, and Seal Island.
of maximum counts at individual colonies observed in five Seventeen of the sites were in South Africa: Rocher Pan,
decadal periods were 2,572 pairs in the 1970s, 2,160 pairs Velddrif Saltworks, Berg River mouth, Hannas Bay Rock,
in the 1980s, 1,521 pairs in the 1990s, 2,147 pairs in the Stompneus Bay Rocks, Meeuw Island, Cape Point, Stony
2000s, and 2,264 pairs in the 2010s (Table 2). These totals Point, Dyer Island, Springfield Soutpan, De Mond Estuary,
will be influenced by the extents of surveys in different pe- Mosselbank in De Hoop Nature Reserve, Jahleel and St
riods, with incomplete coverage underestimating numbers, Croix islands, Bridle Drift Dam, Durban quarry, and Lake
and within-period movements of White-breasted Cormo- St Lucia. Three of the sites, Ilha Sao João da Cazanga,
rants between breeding sites (Crawford 2005, Martin and Mile 4 Saltworks, and Lake St Lucia, had more than 100
Whittington 2024) possibly resulting in overestimation of pairs, and therefore were thought particularly important for
abundance. the southern African coastal population of White-breasted
The sum of the most recent estimates made at colo- Cormorants. Lake St Lucia (233 pairs) had 13% of the most
nies (1,825 pairs) may be the best approximation of the recent coastal population.
coastal population of White-breasted Cormorants in Human disturbance at breeding sites (Martin and Ran-
Angola, Namibia, and South Africa in c. 2020, because dall 1987, Crawford 2005) and loss of suitable nesting
several northern sites were not surveyed in 2018–2022. habitat (e.g. Crawford et al. 2018, Allan 2024, Bowker and
However, it should be borne in mind that values from the Allan 2024, Makhado et al. 2024, Martin and Whittington
1980s contributed c. 13.5% of the most recent estimate of 2024) are probably the greatest threats to southern Africa’s
numbers breeding, from the 1990s c. 1.5%, from the 2000s coastal White-breasted Cormorants. During 1985–1994,
c. 12%, and from 2010–2022 c. 73%; c. 27% of values 124–224 pairs of White-breasted Cormorant bred at Red-
providing the most recent estimate derive from counts made house Saltpans in the Swartkops River valley (Martin and
more than 12 years previously (Table 2). A value of 1,825 Randall 1987). From 2000, the nests there were regularly
pairs in 2020 suggests a decrease from the 2,186 pairs raided by people removing eggs and chicks. This resulted
of 1995–2006 (Kemper et al. 2007) and of > 28% over in White-breasted Cormorants abandoning the colony by
a period of 41 years from the 2,524 pairs of 1977–1981 the end of 2003 (Martin and Whittington 2024). It is possi-
(Brooke et al. 1982), especially as the earlier assessments ble that some of the White-breasted Cormorants relocated
did not cover the northern and eastern portions of the to the Coega Saltpans, where they bred in 2003–2004 and
region. Previously, numbers breeding at islands in South 2007–2008, and to the St Croix group of islands (Craw-
Africa’s Western Cape had decreased from at least 300 ford et al. 2009). White-breasted Cormorants bred again
pairs in 1956 to 191 pairs in 1978 (Brooke et al. 1982). at Redhouse Saltpans in 2009 and then moved to Bar
Great Cormorants attained sexual maturity at 3–5 years, None Saltpans, also in the Swartkops River valley, from
occasionally 2 years (Del Hoyo et al. 1992). Annual survival 2010–2017. The Redhouse and Bar None saltpans ceased
of White-breasted Cormorants was 0.27 in year 1, 0.58 in to operate during 2018 and dried out. From 2018–2022 no
year 2 and 0.78 in year 3 (Skead 1980). Given an average White-breasted Cormorants bred in the Swartkops River
age at first breeding (A) = 4 y, adult survival (φ ) = 0.78 valley. In 2022, the Redhouse Saltpans were re-filled with
α
(it may be higher) and generation length (G) = A + (1 / (1 − freshwater (Martin and Whittington 2024). White-breast-
φ )) (Birdlife International 2000), G = 8.5 years (or more). ed Cormorants were displaced from Jahleel Island in the
α
In KwaZulu-Natal, White-breasted Cormorants fledged an 2000s by human disturbance (BMD unpubl.). Two sites in
average of 1.6 chicks per nest (Olver and Kuyper 1978). the greater Durban area and one at Richards Bay were
Breeding success of Great Cormorants may increase with rendered unsuitable for breeding by urban or industrial
experience (Bregnballe 2006). development (Allan 2024, Bowker and Allan 2024). White-
The decrease of > 28% over 41 years, or 4.8 G, between breasted Cormorants stopped breeding at Marcus Island
1979 and 2020 was equivalent to > 15% in 3 G, which is 10 years after that island was joined to the mainland by a
less than the 30% required for classification as Vulnerable causeway (Makhado et al. 2024). At Geyser Island, White-
(VU, IUCN 2022). Therefore, the listing of LC for White- breasted Cormorants were displaced from their breeding
breasted Cormorants in Namibia and South Africa should site by Cape Fur Seals (Arctocephalus pusillus pusillus)
be retained. However, further monitoring should be under- (Crawford 2005).
taken to better understand the present rate of change of In KwaZulu-Natal, breeding failures by White-breasted
the population. It would also be useful to know whether Cormorants were mainly due to eggs and chicks falling
numbers of White-breasted Cormorants breeding inland in from nests in storms or being kicked out of nests during
southern Africa are changing. changeovers (Olver and Kuyper 1978). At islands, plat-

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