Page 376 - Atlas Sea Birds Ver1

3.7 Numbers, trends, status, and conservation of Bank Cormorant
(Phalacrocorax neglectus)

Authors: DB Tom, PA Bartlett, RJM Crawford, J-A Delport, BM Dyer, R Jones, L Upfold, and AB Makhado

Abstract:
The Bank Cormorant (Phalacrocorax neglectus) is endemic to the Benguela ecosystem and has bred at 59 sites between Hollamsbird
Island in Namibia and Quoin Rock in South Africa, of which 19 are in Namibia and 40 in South Africa. However, by 2022 breeding had
ceased at 18 sites, so that only 41 colonies remained extant. Sums of maxima at sites decreased by 80% over 42 years from 8,672 pairs in
1978–1980 to 1,742 pairs in 2020–2022. Generation length (G) for Bank Cormorants was ≥ 7.5 years; hence the decrease was equivalent
to ≥ 43% in 3G and met IUCN’s Red List criterion A2 for classification as Vulnerable (VU). In 2020–2022, Namibia had 68% of the overall
population and South Africa 32%. Based on the most recent counts at breeding sites, the three largest colonies were at Mercury Island
(54% of the species’ population), Groot Paternoster Rocks (5%), and Ichaboe Island (3%). Eleven sites in Namibia and 15 in South Africa
held ≥ 10 pairs and so met criterion A1 for an Important Bird and Biodiversity Area for a VU species.
Introduction:
Bank Cormorants (Phalacrocorax neglectus) are endemic to the Benguela upwelling ecosystem, where they have bred at 59 sites between
Hollamsbird Island in Namibia and Quoin Rock in South Africa (Figure 1). Of these, 19 are in Namibia and 40 in South Africa. Farther north,
birds in breeding plumage were observed undertaking courtship displays at the mouth of the Swakop River, Namibia, but no breeding was
confirmed at that site (Williams 1987).
This chapter collates information on numbers breeding at the different sites in order to examine trends in the Bank Cormorant population.
It assesses the Red List status of, identifies Important Bird and Biodiversity Areas (IBAs) for, and summarises threats to the species.

Numbers contributed 92% of the sum of most recent counts, from the
2000s 5%, and from the 1990s the balance of 3% (Table
Counts of nests or breeding pairs of Bank Cormorants 2), so estimates for most of the population were obtained
were collated from Rand (1952, 1963), Shaughnessy in the past 13 years. The decrease in 2020–2022, after a
(1980), Cooper (1981), Williams (1987), Williams and Dyer period of apparent stabilisation, is of concern and should
(1990), Crawford et al. (1999, 2008, 2015, 2018), Bartlett be confirmed by ongoing monitoring.
et al. (2003), Du Toit et al. (2003), Kemper et al. (2007),
AEWA (2015), and Roux and Kemper (2015), as well as Population trends and conservation status
from unpublished records of Namibia’s Ministry of Fisheries
and Marine Resources and South Africa’s Department Across a period of 42 years, the overall population of
of Forestry, Fisheries and the Environment. Maximum Bank Cormorants decreased by 80% from 8,672 pairs in
numbers breeding annually at each site are shown in Table 1978–1980 (Crawford et al. 1999) to 1,742 pairs in 2020–
1. 2022 (Table 2). Generation length (G) for the species was
Previously published estimates of numbers of Bank calculated as: G = A + (1 / (1 − ϕ )), where A is age at
α
Cormorants breeding in Namibia and South Africa in first breeding and φ is adult survival (Birdlife International
α
different periods (Cooper 1981, Crawford et al. 1999, 2015, 2000). The mean age at first breeding of Bank Cormorants
Kemper et al. 2007, AEWA 2015) are shown in Table 2. Also was 2.5 years (Crawford et al. 2001). Adult survival has
shown are estimates for two recent 3-year periods (2017– not been measured but, from comparison with other
2019 and 2020–2022), which were obtained by summing cormorants, was thought to be at least 80% p.a. (Crawford
the maximum values recorded at each colony in those et al. 1991, Crawford and Cooper 2005). An estimate of
periods, and for five decadal periods (1970s, 1980s, 1990s, adult survival for the species should be made from ringing
2000s, and 2010s) that were similarly derived. About 8,672 and recapture records to obtain a firmer appraisal of G.
pairs of Bank Cormorants bred from 1978–1980 (Crawford
et al. 1999). This value excluded unoccupied nest mounds
at breeding areas. Cooper’s (1981) estimate included
unused nests and was accordingly 350 pairs more. About
8,650 pairs bred in the 1970s and 1980s and c. 8,200 in
the 1990s (Table 2). However, numbers breeding fell to
c. 4,900 pairs in 1995–1997 (Crawford et al. 1999). Sums
of maxima at sites suggested that c. 4,300 pairs bred in
the 2000s and 4,400 in the 2010s (Table 2), levels about
half of those for the 1970s–1990s. The estimate of c. 2,850
pairs by Kemper et al. (2007) was probably too low and
that of c. 3,650 pairs by AEWA (2015) more correct. Sums
of maxima were 3,682 pairs for 2017–2019 and 1,742 pairs
for 2020–2022 (Table 2), suggesting the overall population
is still decreasing. The total of the most recent counts
obtained at colonies was 1,632 pairs, which is 94% of Bank Cormorants breeding on old jetty at Robben Island (photo
the total for 2020–2022 (Table 2). Data from 2010–2022 L Upfold)

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