Page 176 - Atlas Sea Birds Ver1

expenditure to cool in the sea is less than would be re- penguins were taken from the island to prevent their
quired for birds moulting inland. becoming oiled, so that c. 22,000 grown penguins were
Cape Cormorants nested on an old jetty, walls of the har- removed from Robben Island (Crawford et al. 2000). The
bour and a platform deployed northwest of the island in clean birds were transported to and released at Cape
2004 and 2005 to mitigate loss of breeding space during Recife, about 700 km east of Robben Island. Most of
repair of the harbour’s long arm, Bank Cormorants on the these translocated birds returned to Robben Island, often
jetty and harbour walls and White-breasted Cormorants on rapidly. Three birds tracked by satellite after translocation
the platform. Half a century earlier White-breasted Cormo- took 15–21 days to return to their home colonies (Barham
rants bred at the island in 1950 and 1951 (Brooke 1983). et al. 2006). By the time they did so the beaches had been
Crowned Cormorants nested in trees and bushes, in the cleared of oil (Crawford et al. 2000). Since most chicks at
latter case often in a heronry. Gulls and terns nested on the island were orphaned through removal of their parents,
the ground, including in former quarries. Localities used by about 2,640 chicks were taken from Robben Island for
Hartlaub’s Gull and Greater Crested Tern for breeding from captive rearing and subsequent release. It is thought that
1989–1993 were mapped by Crawford et al. (1994) and c. 3,000 chicks died at Robben Island before they could be
showed that sites often changed between breeding sea- rescued (Crawford et al. 2000).
sons. Levels of human disturbance at sites likely influenced In spite of the massive impact of the Treasure spill on
their use for breeding by these two seabirds (Crawford and Robben Island’s penguins, growth of the colony continued
Kroese 2000). until 2004. The rapid increase of penguins at the island
Three metric tons of seabird guano were collected from after recolonisation was assisted by immigration of first-time
the long arm of Murray’s Bay harbour in 1990 and two breeders from other colonies, notably Dyer Island (Whit-
metric tons in 1992 (Tom et al. 2024). tington et al. 2005), and a high availability of food (sardine
Conservation status: Robben Island was declared a Sardinops sagax and anchovy Engraulis encrasicolus) at
National Historical Monument in 1995 and is managed by the turn of the century (Underhill et al. 2006). The decrease
Robben Island Museum, primarily for the historical and cul- in penguins after 2004 followed a shift to the southeast in
tural value of the site (Barnes 1998). the distribution of sardine and anchovy (Crawford et al.
Species and numbers breeding: Numbers of pairs of dif- 2011) and a reduced availability of these prey species to
ferent seabird species that bred annually at Robben Island epipelagic predators off South Africa’s west coast (Craw-
are shown on the following table applicable to this island. ford et al 2019). Survival of adult penguins at Robben Is-
African Penguins bred at Robben Island from as land decreased after a collapse of South Africa’s sardine
early as 1620 and did so until the late 1700s, when hunting stock in the early 2000s (Sherley et al. 2014a) and was
of penguins for their oil likely brought about extinction of the negatively related to the biomass of sardine (Robinson
colony (Crawford et al. 1995a). They recolonised the island et al. 2015, Crawford et al. 2022) and an index of food
at its northwest in 1983, when nine pairs were observed availability (Crawford et al. 2019). Reproductive success
breeding under bushes. The breeding area of penguins of penguins at the island was negatively related to the
subsequently expanded considerably as the colony grew biomass of sardine and anchovy (Cury et al. 2011). The
and its distribution was mapped by Crawford et al. (1995a), chick fledging period was negatively correlated with prey
Crawford and Dyer (2000) and Sherley et al. (2014b). Num- abundance (Sherley et al. 2013). During the decrease
bers breeding increased steadily from 1983 to a maximum of the penguin colony the area it occupied did not shrink
of c. 7,800 pairs in 2004, apart from decreases of c. 500 markedly; rather the density of nests decreased (Sherley
pairs between 1994 and 1995, following the loss of 1,200 et al. 2014b). At Robben and Dassen islands, closures of
birds after the Apollo Sea oil spill in 1994 (Crawford et al. the purse-seine fishery for sardine and anchovy within the
1999b), and of 1,100 pairs between 2002 and 2003. penguins’ primary foraging range increased their breeding
In June 2000, oil washed ashore at Robben Island productivity and often reduced parental foraging efforts,
after the Treasure spill to the north of the island. The oil indicating that the fishery was competing with the birds
covered beaches used by penguins to leave from and for food (Sydeman et al. 2021).
return to the island and all penguins crossing the beaches Great White Pelicans were assumed have bred at
were oiled. Robben Island in 1604, 1607 and 1610 but there are no
About 14,825 oiled penguins were caught at the island more recent records of them nesting at the island (Brooke
for cleaning and rehabilitation. Additionally, 7,161 unoiled 1983). The population in the Western Cape has moved

A view across Robben Island (photo L Upfold) The Robben Island quarry (photo L Upfold)

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