This species is listed as Vulnerable since it has a very small breeding range on just six islands, and over-exploitation of its prey by human fisheries - compounded by pollution - is causing a continuous decline in the quality of surrounding waters for foraging.
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: #http://www.aerc.eu/DOCS/Bird_taxa_of _the_WP15.xls#.
Christidis, L.; Boles, W. E. 2008. Systematics and taxonomy of Australian birds. CSIRO Publishing, Collingwood, Australia.
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.
SACC. 2006. A classification of the bird species of South America. Available at: #http://www.museum.lsu.edu/~Remsen/SACCBaseline.html#.
Sula capensis Dowsett and Forbes-Watson (1993)
Distribution and populationMorus capensis
84-94 cm. Sleek, mainly white seabird. Black tail, primaries and secondaries. Pale yellow head. Immature dark brown, mottled paler, and shows increasing amounts of adult plumage after first year. Similar spp. Adult Masked Booby Sula dactylatra has white head, adult Northern Gannet Morus bassanus has white tail and secondaries, adult Australasian Gannet S. serrator has only four, occasionally more, black central tail feathers. Voice Usually silent at sea. Rasping arrah arrah is most common call at colonies.
breeds at just six islands: Bird (Lambert's Bay), Malgas and Bird (Algoa Bay), South Africa
, and Mercury, Ichaboe and Possession, Namibia
. Historically it bred on four more islands (Kemper et al
. 2007). Outside the breeding season, adults are generally sedentary but young range east to KwaZulu-Natal, Angola, Mozambique and Tanzania, and regularly north as far as Nigeria, but usually within 100 km of land. In 1996, the global population numbered c.173,000 breeding pairs: 153,000 (88.4%) in South Africa, the balance in Namibia. The total breeding population in 2004-2006 was c.150,000 pairs (Kemper et al
. 2007). Exchange occurs between breeding localities. Although the numbers breeding at South African islands increased between 1956 and 1996, the Namibian population declined massively. The total breeding population has decreased by 1.14% per year over the 49 years between 1956-1957 and 2005-2006, equivalent to 36% over 39 years (Kemper et al
. 2007). Over a 50 year period, numbers at the three Namibian colonies fell by 85-98%, with greater proportional decreases in the south (Crawford et al.
2007). The colony at Lambert’s Bay increased between 1956-57 and 2003-04, but attacks by Cape Fur Seal Arctocephalus pusillus
on birds on nests caused abandonment of the whole colony in 2005-05 (Crawford et al.
2007). The colony at Possession Island now numbers only 750 pairs, and may soon be lost. Population justification
The total breeding population in 2004-2006 was c.150,000 pairs.Trend justification
The total breeding population declined by 1.14% per year over the 49 years between 1956-1957 and 2005-2006 (Kemper et al. 2007), equivalent to c.47% over 60.6 years (three 20.2-year generations).EcologyBehaviour
This species is not strictly migratory and the majority of birds remain within 500km of their breeding site year round (del Hoyo et al.
1992), some (mainly adult males) continuing to use the breeding grounds as roosting sites throughout the non-breeding season (Nelson 2005). However some adults disperse up to 3300 km from the breeding colonies, moving along the African coast for about 3 months during the non-breeding season (Hockey et al.
2005; Nelson 2005). Juveniles disperse northwards in April (del Hoyo et al.
1992, Nelson 2005), travelling up to 4000 km towards the equator (Nelson 2005) where they may remain for over a year (Nelson 2005), returning to breed around four years of age (Makhado et al.
2006). Breeding occurs between September and April in large colonies of up to 5000 pairs (Nelson 2005), although it will also nest in much smaller groups (Nelson 2005). Large foraging aggregations occur around trawling vessels (del Hoyo et al.
1992). Individuals can travel as much as 450 km in a day in search of food (Mullers 2009). Habitat
This species is strictly marine. Breeding
It prefers to nests on flat or gently sloping open ground on offshore islands (Hockey et al.
2005), but will also use island cliffs as well as man-made structures such as guano platforms (Nelson 2005). Non-breeding
It most often forages within 120km of the shore (Adams and Navarro 2005), particularly frequenting areas where purse-seine netting occurs (Nelson 2005), but occasionally wanders further offshore over the continental shelf (del Hoyo et al.
1992) where it benefits from the discards of deep-water stern trawlers (Nelson 2005). Diet
It feeds mainly on shoaling pelagic fish (del Hoyo et al.
1992) such as anchovy Engraulis capensis
, sardine Sardinops sagax
or saury Scomberesox saurus
, as well as offal discarded by fishing boats including demersal fish (Hockey et al.
2005). In South Africa fluctuations in the contribution of E. capensis
and S. sagax
in the diet match the changing abundance of the species (Crawford and Dyer 1995, Crawford et al.
2007). Breeding site
The nest consists of a mound with a cup-shaped depression in its centre (Nelson 2005). It is made from guano, vegetation and other matter that can be scraped together (Hockey et al.
2005). Where no such material is available, eggs are laid on bare ground (Hockey et al.
2005). . Threats
Food shortage, following the collapse of the Namibian sardine fishery, has been the main cause of declines. In Namibia anchovies only temporarily and partially replace sardines in the diet when the latter becomes scarce (Crawford et al.
2007). In both Namibia and South Africa, the numbers of Cape gannets breeding were significantly related to the biomass of epipelagic fish prey (Crawford et al.
2007). Oil-spills are also a serious threat: c.5,000 M. capensis
were oiled during an incident in 1993. Guano collection may decrease breeding success, as it inhibits some birds from laying (through human disturbance and lack of quality nesting habitat through excessive removal of guano) and reduces the effective breeding season (Kemper et al.
2007). The Cape Fur Seal Arctocephalus pusillus
displaced M. capensis
from Hollam's Bird Island and killed 27,000 fledglings over the course of three breeding seasons on Malgas Island, equating to a 25% reduction in the size of the colony and threatening the sustainability of the population (Makhado et al.
2006). They also caused the abandonment of a colony at Lambert's bay in 2005/2006 (Crawford et al.
2007), although historically a programme to discourage seals on Mercury Island was largely effective (Harrison et al.
1997). Other threats include predation by Great White Pelicans Pelecanus onocrotalus
which are a significant threat on chicks in Malgas Island (Mullers 2009), by-catch during longline fishing, exploitation for food in southern Angola, nesting habitat degradation by excessive guano removal and flooding of nests during storms (Kemper et al
. 2007). Conservation Actions Underway
In South Africa, Lambert's Bay and Bird Island are nature reserves and Malgas Island is within West Coast National Park. In Namibia, the three breeding islands are administered by the Ministry of Fisheries and Marine Resources. All six islands have been identified as Important Bird Areas (IBAs) (Barnes 1998)
. Oiled birds are rehabilitated with success in South Africa, and the species is protected by law.Conservation Actions Proposed
Carry out surveys to obtain an up-to-date population estimate. Conduct regular surveys to monitor population trends. Develop and implement a sustainable, coordinated fisheries plan for the region. Develop measures to prevent oilspills from illegal cleaning of ship tanks. Consider the potential culling of individual seals that are inflicting excessive mortality on, or causing extensive disturbance to, threatened colonies (Crawford et al.
Related state of the world's birds case studies
Adams, N.J. and Navarro, R.A. 2005. Foraging of a coastal seabird: flight patterns and movements of breeding Cape gannets Morus capensis. African Journal of Marine Science 27(1): 239-248.
Barnes, K. N. 1998. The Important Bird Areas of southern Africa. BirdLife South Africa, Johannesburg.
Barnes, K. N. 2000. The Eskom Red Data Book of birds of South Africa, Lesotho and Swaziland. BirdLife South Africa, Johannesburg.
Crawford, R.J.M. and Dyer, B.M. 1995. Responses by four seabird species to a fluctuating availability of Cape anchovy (Engraulis capensis) off South Africa. Ibis 127: 329-339.
Crawford, R.J.M., Dundee, B.L., Dyer, B.M., Klages, N.T.W., Meyer, M.A. and Upfold, L. 2007. Trends in numbers of Cape gannets (Morus capensis), 1956/1957-2005/2006, with a consideration of the influence of food and other factors. ICES Journal of Marine Science 64(1): 169-177.
del Hoyo, J.; Elliot, A.; Sargatal, J. 1992. Handbook of the Birds of the World, vol. 1: Ostrich to Ducks. Lynx Edicions, Barcelona, Spain.
Harrison, J. A.; Allan, D. G.; Underhill, L. G.; Herremans, M.; Tree, A. J.; Parker, V.; Brown, C. J. 1997. The atlas of southern African birds. BirdLife South Africa, Johannesburg.
Hockey, P. A. R.; Dean, W. R. J.; Ryan, P. G. 2005. Roberts birds of southern Africa. Trustees of the John Voelcker Bird Book Fund, Cape Town, South Africa.
Kemper, J.; Underhill, L. G.; Crawford, R. J. M.; Kirkman, S. P. 2007. Revision of the conservation status of seabirds and seals breeding in the Benguela Ecosystem. In: Kirkman, S. P. (ed.), Final Report of the BCLME (Benguela Current Large Marine Ecosystem), pp. 325-342.
Makhado, A.B., Crawford, R.J.M. and Underhill, L.G. 2006. Impact of predation by cape fur seals Arctocephalus pusillus pusillus on Cape gannets Morus capensis at Malgas Island, Western Cape, South Africa. African Journal of Marine Science 28(3-4): 681-687.
Mullers, R. 2009. Cape Gannet threatened with extinction. Available at: #http://www.wildlifeextra.com/go/news/cape-gannet090.html#.
Nelson, J. B. 2005. Pelicans, cormorants and their relatives. Pelecanidae, Sulidae, Phalacrocoracidae, Anhingidae, Fregatidae, Phaethontidae. Oxford University Press, Oxford, U.K.
Further web sources of information
Australian Govt - Action Plan for Australian Birds 2000 - Recovery Outline
Explore HBW Alive for further information on this species
Search for photos and videos, and hear sounds of this species from the Internet Bird Collection
Text account compilers
Anderson, O., Calvert, R., Ekstrom, J., Malpas, L., Pilgrim, J., Robertson, P., Taylor, J.
IUCN Red List evaluators
Butchart, S., Symes, A.
BirdLife International (2014) Species factsheet: Morus capensis. Downloaded from
http://www.birdlife.org on 24/09/2014.
Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from
http://www.birdlife.org on 24/09/2014.
This information is based upon, and updates, the information published in BirdLife International (2000)
Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004)
Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.
To provide new information to update this factsheet or to correct any errors, please email BirdLife
To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.
Additional resources for this species