Page 350 - Atlas Sea Birds Ver1

et al. 2016) and 3G = 27.75 years. Cook (2015) used a
slightly shorter G = 8.67 years but did not describe its
derivation.
There was a decrease of c. 64,000 pairs (24%) in the
overall population of Cape Cormorants, from 250,000 pairs
in 1978/79 to 189,000 pairs in 2020/21, a period of 42
years or 4.5 G. This is equivalent to a decrease of c. 16% in
3G, which is less than the lower threshold of 30% required
for categorisation as Vulnerable (VU, IUCN 2022). Hence
the species should no longer be regarded as Threatened.
However, given that in 2020/21 half the species population
resided at one site in Angola and that numbers in Namibia
and South Africa remained depressed, it would be prudent
to regard it as Near Threatened.
The Namibian population decreased by 95,500 pairs
(65%) from 143,000 pairs in 1978/79 to c. 50,000 pairs
in 2020/21, a rate equivalent to 43% in 3G. This meets
Juvenile Cape Cormorants (photo M van Onselen) the lower threshold of ≥ 30% for classification as VU but
not that of ≥ 50% for consideration as EN. The South
15,000 pairs at Malgas Island, and 11,000 pairs at African population decreased by 86,000 pairs (83%) from
Vondeling Island (Table 1). 104,000 pairs in 1978/79 to 18,000 in 2021/22 (4.65G),
The overall population of Cape Cormorants was a rate equivalent to 53.5% in 3G. This rate is sufficiently
of the order of 100,000 pairs in 1956/57, increased to high to warrant continued classification as EN. If, for South
c. 250,000 pairs in 1978/79, but reverted to c. 100,000 pairs Africa, the sum of the most recent counts (28,000 pairs)
in 2005/06 (Crawford et al. 2007). The sums of maxima is used instead of the 2021/22 count as an index of the
at sites were c. 108,000 pairs in 2013–2017 and present population, the decrease of 73,000 pairs (73%)
c. 234,000 in 2018–2022 (Table 2). However, there may in 4.5G, from 1978/79 to 2020/21, is equivalent to 49% in
be considerable inter-seasonal movements of Cape 3G, marginally below the 50% required for classification as
Cormorants between breeding sites (Crawford et al. 1994), EN. However, the mean of the two rates (51%) supports
so sums of maxima across several years may overestimate retention of an EN classification.
abundance. In 2020/21, the total of counts at sites was
c. 189,000 pairs (Table 2). The total of the most recent Important Bird and Biodiversity Areas
counts made at each site was c. 187,000 pairs, of which
> 99% was contributed by observations made between Important Bird and Biodiversity Areas (IBAs) are identified
2010 and 2022 (Table 2). This is similar to the estimate for through the use of specific criteria. Criterion A1 is that
2020/21 and suggests that, following a decrease of c. 60% ‘the site is known or thought regularly to hold significant
between the 1970s and early 2000s, by 2020 the overall numbers of a Globally Threatened species’ (BirdLife
breeding population had recovered to c. 75% of its level in International 2020). Guidelines for the application of
the 1970s. The recent increase was almost entirely due to IBA criteria recommend that to meet A1 a site must
growth at the northernmost site of Ilha dos Tigres, which in support at least 15 individuals (the equivalent of 5 Pairs/
2020/21 held half of the overall population of the species. Reproductive Units) of a species classified as EN, or
In Namibia, about 143,000 pairs of Cape Cormorant 30 individuals (the equivalent of 10 Pairs/Reproductive
bred in 1978/79, which fell to c. 85,000 pairs in 1992/93, Units) of a species classified as VU (BirdLife International
c. 50,000 pairs in 2004/05 (Crawford et al. 2007), and 2020). Although the Cape Cormorant is thought to no
c. 50,000 pairs in 2020 (Table 2). Counts for 2021/22 longer be globally threatened, Ilha dos Tigres, which
were incomplete. holds c. 50% of the overall population, is undoubtedly of
In South Africa, about 104,000 pairs bred in 1978/79, considerable importance for the species and, since the
c. 73,000 pairs in 1992/93, c. 50,000 pairs in 2004/05 Namibian and South African populations both continue
(Crawford et al. 2007), c. 57,000 pairs from 2010–2014 to decrease and meet criteria for regional classification
(Crawford et al. 2016), c. 44,000 in 2020/21 (Table 2), and as VU and EN respectively, other sites holding ≥ 10 pairs
c. 18,000 in 2021/22 (Table 1). The total of the most recent should also be considered important breeding sites for
counts at colonies was c. 28,000 pairs (Table 2). the species. There are 20 such sites in Namibia and 26 in
In 2015, Cape Cormorants were classified as Endangered South Africa, making 46 in total (Table 2). However, more
(EN) in Namibia (Kemper and Simmons 2015) and in South recent observations are needed to confirm that, in Namibia,
Africa (Cook 2015). In 2022, they were classified as EN by Die Oase, Terrace Bay, Sandwich Harbour, Hollamsbird
the International Union for Conservation of Nature (IUCN, Island, the Sylvia Hill environs, Oyster Cliffs, North Head,
BirdLife International 2022). Dolphin Head, and Devil’s Islet continue to hold sufficient
Generation length (G) for Cape Cormorants may be numbers of breeding birds to meet the IBA criterion.
calculated as A + 1 ⁄ (1 – ϕ ), where A is age at first breeding If ‘Super Sites’ are defined as those supporting ≥ 1% of
α
and ϕ is adult survival (BirdLife International 2000). Then, the population, at present seven sites would qualify as such:
α
given A = 3 years (when food is plentiful, some birds may Ilha dos Tigres in Angola; Mile 4 platforms and Ichaboe and
breed at two years; Crawford et al. 2001) and ϕ = 0.84 per Possession islands in Namibia; and Jutten, Dassen, and
α
annum (Crawford et al. 1992b), G = 9.25 years (Crawford Dyer islands in South Africa (Table 2). However, given the

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