- Morus capensis
Sula capensis
Identification
Adult
- Mostly white
- Black flight feathers
- Black tail
- Buffy on head
- Narrow stripe from bill down center of chin and throat
The all black tail separates the adult from Northern Gannet and Australian Gannet, but it would be difficult to separate from Masked Booby.
Distribution
Their breeding habitat is restricted to southern Africa in three islands off Namibia and three islands off South Africa. They normally nest in large and dense colonies on flat islands or on flat ledges of the steeply sloping Mercury Island off Namibia. The world population was estimated in 1996 to number about 340,000 birds, with 12% in Namibia and 88% in South Africa. The largest colony of this bird, with over 140,000 birds, is found on Malgas Island, South Africa.
The non-breeding range of Cape gannets extends from the coastal waters off the Gulf of Guinea on the west coast of Africa, to Mozambique on the east coast.
Taxonomy
This is a monotypic species[1].
Habitat
They seldom occur farther offshore than 100 km, though records of birds more than 200 km offshore exist for both the Atlantic and Indian Oceans.
Behaviour
Cape Gannets are powerful fliers, using mainly a flap-gliding technique, which is more energy consuming than the dynamic-soaring favoured by albatrosses.
Diet
As all gannets, they are fish-eating birds that plunge-dive from considerable height.
Breeding
The hatchling is black, naked and blind, it weighs only about 70 grams, but within three weeks its body mass is one third of that of an adult. At eight weeks the chick outweighs the adult, and this remains so until it becomes a fledgling at 95-105 days of age.
Status
The Cape Gannet is listed in the 2007 IUCN Red List as Vulnerable due to the very small breeding range, the decline in fish stocks in its foraging waters, and the impact of pollution (Birdlife International, 2007).
Numbers of Cape Gannets at the Namibian islands have declined considerably between 1956 and 2000 from 114,600 to 18,200 breeding pairs respectively, an 84% decrease in less than fifty years. This contrasts with the trends at the South African islands where numbers have increased about 4.3 times during the same period, from 34,400 to 148,000 breeding pairs.
References
- Clements, JF. 2009. The Clements Checklist of Birds of the World. 6th ed., with updates to December 2009. Ithaca: Cornell Univ. Press. ISBN 978-0801445019.
- BirdLife International (2007)
Recommended Citation
- BirdForum Opus contributors. (2024) Cape Gannet. In: BirdForum, the forum for wild birds and birding. Retrieved 29 May 2024 from https://www.birdforum.net/opus/Cape_Gannet
External Links
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