Page 336 - Atlas Sea Birds Ver1

ousted from Quoin Rock by a growing colony of Cape Fur
Seals (Arctocephalus pusillus pusillus) (Rand 1963, Brooke
1984). They moved to Seal Island (False Bay) but growth
of the seal herd at that island and disturbance by sealers
caused them to leave it for Dassen Island (Rand 1963,
Crawford et al. 1995). It is likely that the few pairs that bred
at Vondeling Island in 2001 and 2005, and at Jutten Island
in 2012 were from Dassen Island. The breeding attempts at
Vondeling Island coincided with colonisation of that island
by Cape Fur Seals (Seakamela et al. 2024), and, because
Great White Pelicans fed on chicks of threatened, endemic
seabirds (Mwema et al. 2010), their colonisation of Jutten
Island was discouraged (Makhado et al. 2024). Numbers of
pelicans breeding in southwest South Africa grew from 20–
A White Pelican feeding a chick (photo L Upfold) 30 pairs in the early 20 century to > 500 pairs in 1993. This
th
increase was attributed to an increased number of coastal
1949, after construction of the platform was completed in
1939 (Berry et al. 1973, Berry 1975). Colonisation of the waterbodies, some stocked with introduced fish, availability
platform appeared to have resulted from former breeding of agricultural offal as food, and lack of disturbance at their
islands at Sandwich Harbour becoming unsuitable nesting Dassen Island breeding sites (Crawford et al. 1995). The
sites through their joining the mainland and so providing growth continued to a maximum of 834 pairs in 2004; then
access for mammalian predators (Crawford et al. 1981). numbers fell to 250–450 pairs from 2010–2021 (Figure 3), it
Pelicans nested at Sandwich Harbour until 1947 (Berry and was thought mainly as a result of a decrease in agricultural
Berry 1975). Between 2000 and 2004, pelicans again bred offal (Kemper et al. 2007). At Dassen Island, Great White
in small numbers on islands inaccessible to predators at Pelicans also ate chicks of Kelp Gulls (Larus dominicanus),
Sandwich Harbour but breeding ceased when those islands causing a decrease in the number and density of Kelp
disappeared (Simmons 2015). The numbers of pelicans Gull nests at the island, and therefore that food source
breeding at Bird Rock Platform decreased substantially (Crawford et al. 2009).
from 524 pairs in 1967 to about eight pairs from 2006 to At Lake St Lucia, Great White Pelicans bred at Lane
2020 (Figure 2). It is possible that at the start of the present and Bird islands, Selley’s Lakes, and North False Bay,
century some pelicans moved to other localities in the interchanging between these sites (Bowker and Downs
region, such as Ilha dos Tigres and Hardap Dam. 2008a, Fox et al. 2024). Maxima observed at these localities
In Namibia, in 2015 the population of Great White were 2,500 pairs at Lane Island in 2011, 2,200 pairs at Bird
Pelicans was c. 3,000–4,000 birds (Simmons 2015), which Island in 2002, 2,668 pairs at Selley’s Lakes in 1998, and
was a noticeable decrease from the 6,600 adults that bred 1,000 pairs at North False Bay in 2021 (Table 1). There
there in 1971 (Berry et al. 1973, Crawford et al. 1981). was high variability in the overall numbers breeding at Lake
In southwest South Africa, Great White Pelicans were St Lucia, especially after the 1970s (Figure 4). There was
assumed to have bred at Robben Island in the 1600s but also high variability in breeding success. From 1950–2005,
they were not recorded to have done so later (Brooke 1983). breeding was not attempted or failed in 23 (41%) of the
They nested at Dyer Island from c. 1869 to 1919 (Brooke 56 potential breeding seasons. Six (23%) of the failures
1984), at Quoin Rock from 1894 to 1902, at Seal Island were due to flooding of the nest sites (Bowker and Downs
(False Bay) from 1930–1956, and at Dassen Island from 2008a). Failure also occurred as a result of drying out of
1956to at least 2022 (Crawford et al. 1995, Visagie et al. the lake, which linked islands to the mainland and allowed
2024). Persecution of pelicans by guano collectors at Dyer access by mainland predators (Bowker and Downs 2008b).
Island led to cessation of their breeding there and they were Bowker and Downs (2008a) noted that under abnormal

500
800
400
600
PAIRS 300 PAIRS

400
200

200
100

1955 1961 1967 1973 1979 1985 1991 1997 2003 2009 2015 1971 1976 1981 1986 1991 1996 2001 2006 2011 2016

Figure 2. Numbers (pairs) of Great White Pelicans breeding at Figure 3. Numbers (pairs) of Great White Pelicans breeding at
Bird Rock Platform, 1956–2020 Dassen Island, 1971–2021

330