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SEABIRDS
GENERAL INFORMATION
Southern Africa is an important area for seabirds as the coastal waters are rich in nutrients and forage species (such as
sardines) and the islands provide valuable nesting sites for a diversity of species. According to the WWF, South Africa is
the fourth most important coastal state, in terms of seabird range, following New Zealand, Australia and Chile. It is also
an extremely important area in terms of seabird conservation and management as 15 of the 24 endangered albatross and petrel
species forage in our coastal waters. Albatrosses are some of the biggest birds in the world, and their giant wingspan (up
to 3.5m in some species) allows them to travel vast distances, often more than 7000km for a non-breeding animal, in search
of food.
BIOLOGY
Many seabird species have very conservative life-history strategies, meaning they are long-lived, slow to breed and have
delayed sexual maturity. In fact, many seabirds are more similar to mammals in terms of life-history than they are to other
bird species. For instance, albatrosses and petrels can live longer than 60 years, they lay only one egg per year and some
species only breed once every second year and most species only start breeding after 10 years of age. These characteristics
make their populations very vulnerable to human-induced sources of mortality (e.g., pollution, bycatch), and a few
mortalities may lead to significant population declines.
FEEDING
Seabirds are opportunistic scavengers, meaning they eat and swallow anything they encounter. However, seabirds do prefer
certain diets and albatrosses and petrels mostly feed on squid, small fish and crustaceans. Kelp gulls are voracious
predators and will kill the chicks of many other seabird species. Some smaller albatrosses and petrels can dive to depths of
>10m in search of food, but most albatrosses are limited to the surface as their giant wing span prevents them from
diving. Albatrosses feed during the day while petrels feed during both day and night.
THREATS
Seabirds are one of the most threatened groups of animals in the world. According to the WWF, 19 of 21 species of albatross,
one species of giant petrel and four small petrel species are threatened with extinction. This is primarily due to
mortalities associated with fishing vessels where seabirds are accidentally killed in vast numbers. This is known as
bycatch. Other threats include pollution, habitat degradation, hunting, human disturbance and introduced predators (e.g.,
rats and mice) which prey on nesting birds.
CONSERVATION
Many fishermen are now required by law to implement bird bycatch mitigation measures - measures intended to reduce the
numbers of birds caught and killed in fishing operations. These include the use of bird scaring lines (or tori lines), sink
rate specifications (the rate at which longline gear sinks) using weighted gear and setting gear at night when bird numbers
are lower. Other conservation measures include the eradication of introduced predators on nesting islands and the
regeneration of valuable habitat.
A list of some common and uncommon bird species in South African waters:
Species
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Conservation Status (IUCN Red List, 2006)
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Image
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Wandering Albatross (Diomedea exulans)
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Vulnerable
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Northern Royal Albatross
(Diomedea sanfordi)
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Endangered
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© XLerate
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Shy Albatross (Thalassarche cauta)
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Near Threatened
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© Mjobling
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Black-browed Albatross (Thalassarche melanophrys)
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Endangered
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© David (no surname available)
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Yellow-nosed Albatross (Thalassarche chlororhynchos)
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Endangered
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© Steven Chown
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Cape Gannet (Malgas) (Morus capensis)
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Vulnerable
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© Rene Navarro
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Northern Giant Petrel (Macronectes halli)
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Near Threatened
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Southern Giant Petrel (Macronectes giganteus)
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Vulnerable
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© Ealdgyth
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White-chinned Petrel (Procellaria aequinoctialis)
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Vulnerable
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© Mjobling
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Cape Petrel (Daption capense)
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Near Threatened
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Great Shearwater (Puffinus gravis)
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Least Concern
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© Patrick Coin
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Sooty Shearwater (Puffinus griseus)
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Near Threatened
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© Mike Baird
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Flesh-footed Shearwater (Puffinus carneipes)
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Least Concern
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© Duncan Wright
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Sub-Antarctic Skua (Catharacta Antarctica)
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Least Concern
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© Doug McVeigh
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Kelp Gull (Larus dominicanus)
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Least Concern
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Cory's Shearwater (Calonectris diomedea)
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Near Threatened
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© Tom Allmandinger
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Other sources of information:
Wikipedia
Avian Demography Unit
Birdlife International
Birdlife South Africa
IUCN Red List
© 2008 Dyer Island Conservation Trust
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