Page 152 - Atlas Sea Birds Ver1

In 1903 and 1905, 32,800 African Penguin eggs fledgling mortality rate. However, because seals learned to
were collected at Malgas Island (Makhado et al. 2024). avoid the boat used for their removal, it was not possible to
Conservation status: The island falls within WCNP. remove all the seals that killed gannet fledglings and some
Species and numbers breeding: Eleven seabird species mortality continued. The seals that inflicted the mortality
have bred at Malgas Island. Their numbers are given were all sub-adult males, with an average age of < 5 years
on the following table applicable to this island. Numbers of (Makhado et al. 2006). Attempts have also been made to
African Penguin at the island decreased from c. 2,500 remove seals killing gannets ashore.
pairs in 1956 to just two pairs in 2022. About 25,000 Great White Pelicans have eaten gannet and cormorant
pairs of Cape Gannet bred at the island in 1956. This chicks at the island, especially smaller individuals (Picheg-
increased to > 50,000 pairs in five seasons between 1989 ru et al. 2007, de Ponte Machado 2010), although active
and 1998 but ten fell to c. 20 000 pairs in 2018. More than management put in place by South African National Parks
14,000 pairs of Cape Cormorant bred at the island in since 2008 drastically reduced this impact (Sherley et al.
1956 but fewer than 5,000 pairs did so since 1993. In 2019). Kelp Gulls took 10–70% of the gannet colony’s egg
1990, almost 200 pairs of Bank Cormorant bred at the production between 2012 and 2018 (Sherley et al. 2019),
island but this dropped to only five pairs in 2021, when most of which was after gannets had been displaced from
one pair also bred on top of nearby Needle Rock (BMD nests by seals (BMD pers. obs.). Some damage-causing
pers. obs.). Scarcity of good quality food was likely a Kelp Gulls were culled (AK unpublished information).
main driver of all these decreases (Pichegru et al. 2007, White-breasted Cormorants were last recorded breed-
Crawford et al. 2008, 2011, 2016, 2019, 2022, Grémillet ing at the island in 1926, whereas 46–162 pairs of Crowned
et al. 2008, 2016, Mullers et al. 2009, Cury et al. 2011, Cormorant have bred at the island since 1989 but ≤ 75
Moseley et al. 2012, Cohen et al. 2014, Sherley et al. 2017). pairs since 2014. Numbers of Kelp Gulls breeding at the
Additionally, seals caught adult gannets at their nests on the island increased after the 1980s, attaining a maximum of
island (Crawford and Cooper 1996) and, in the 2017/18 213 pairs in 2011. Maxima of 1,357 pairs of Hartlaub’s Gull
breeding season, such attacks caused the abandonment and 2,130 pairs of Greater Crested Tern bred at the island
of c. 10% of the island’s gannet colony (Sherley et al. 2019). but only solitary pairs of Grey-headed Gull and Caspian
In the early 2000s, seals inflicted unsustainable mortality Tern were recorded. Hartlaub’s Gull and Greater Crested
on gannet fledglings leaving to sea around the island Tern show substantial nomadism between breeding
(Makhado et al. 2006). In 2007, 61 seals that preyed on localities but Caspian Tern changes localities less
gannet fledglings were culled, significantly reducing the frequently (Crawford et al. 1994).
Numbers (pairs) of different seabird species breeding at Malgas Island, 1648–2021

African Cape Gannet Crowned Kelp Gull Greater
Year Penguin Cape Cormorant Bank Cormorant White- breasted Cormorant Cormorant Hartlaub’s Gull Grey- headed Gull Crested Tern Caspian Tern

1648 √
1924 min 1
1925 min 1 1
1926 min 2 2
1929 4
1947 24
1956 2500 25040 14547 102 40
1967 31450 1861 57
1969 28020 5538 62
1977 146 84 350 1
1978 28168 8708 85 0 15 26
1979 1022 453 121 0 57 9 0
1980 30170 6 110 0 55
1981 140 0 65
1982 32940 104 0 59
1983 25510 94 0 71
1984 28570 170 0
1985 28200 21 106 0 56 42
1986 39720
1987 142 41580 79 0 78 0 0
1988 42200 3067 0 39 7 11 0
1989 101 54320 0 164 0 93 21 0 0
1990 118 29690 571 194 0 132 20 59 0
1991 80 44640 5362 119 0 119 56 610 44
1992 99 43280 1199 125 0 108 46 11 0

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