Situated on the Atlantic coast about 150 km north of Cape Town, this small island lies in Lambert’s Bay harbour extremely close to shore. A concrete causeway that forms the fishing harbour has linked the island to the mainland since 1959. Rising to only 7.6 m a.s.l., the island is rocky and virtually devoid of vegetation. The exotic plant Malva parviflora used to be quite common but has not been present since the late 1970s.
Historically, Bird Island was dominated by African Penguin Spheniscus demersus and was devoid of breeding Cape Gannet Morus capensis. It would appear that the gannets first colonised the island in 1912; today it is one of only six localities where they breed. The Cape Gannets form a single undivided colony in the centre of the island. Breeding numbers have fluctuated dramatically: the population declined steadily between 1956 and 1967, but by 1971 it had recovered and by 1981 it was 50% larger than it had been in 1971. Numbers of breeding birds have continued to increase since the early 1980s. When reviewed against the counts conducted for the first southern Africa IBA directory, current numbers suggest that the gannet population has continued to grow.
Cape Cormorant Phalacrocorax capensis has also nested extensively on the island, occasionally reaching a total of 61 000 birds. African Penguin numbers halved between the late 1970s and early 1990s and have subsequently dwindled to a handful of breeding birds. During the IBA assessment it was noted that African Penguin no longer breeds on the island. The decline in numbers is mirrored across the species’ range and many conservation and research organisations are attempting to reverse this trend.
Crowned Cormorant Phalacrocorax coronatus, Kelp Gull Larus dominicanus and occasionally Swift Tern Sterna bergii breed on the outlying rocks. Kelp Gulls have also stopped breeding on the island and have shifted to nearby factory roofs to nest, possibly to find safety from terrestrial predators. Bank Cormorant Phalacrocorax neglectus ceased breeding in 1997 and now only a few individuals roost on the island. Hartlaub’s Gull Larus hartlaubii and various tern species roost in large numbers.
Globally threatened species are Cape Gannet (9 000 breeding pairs; figures for this and the following species from Crawford et al. 2012 and CapeNature census counts), Crowned Cormorant (25 individuals), Cape Cormorant (200 individuals and 30 breeding pairs) and African Black Oystercatcher Haematopus moquini (two individuals). Species reaching the congregatory criteria threshold are Cape Gannet (approximately 6% of the global population) and Kelp Gulls (53 breeding pairs).
The global Cape Gannet population decreased some 50% between 1956 and 1980. The collapse was attributed to the fall in pilchard Sardinops sagax stocks, the gannet’s primary food source. Despite the global decline, the Bird Island colony has been increasing since the 1970s, which correlates with the local recovery of pilchard stocks in the Western Cape. Recent data, from counts conducted by CapeNature, suggest that the population continues to increase, with higher numbers than were estimated in 1998 (Barnes 1998).
African Penguin and Cape Cormorant are thought to have been affected by competition with commercial fisheries, especially purse-seining for surface-shoaling fish such as anchovy Engraulis capensis and pilchard, which are their primary prey. A recommendation was made that marine reserves with a radius of 25 km should be created around important breeding islands, with commercial fishing banned or restricted in these zones. However, in many cases this has not been implemented. Declining fish stocks in the seas around Bird Island represent a major threat to the bird populations. The collapse of African Penguin and other seabird breeding colonies on South Africa’s west coast has been attributed to competition with commercial fisheries. This threat may continue to have a negative impact on the gannet and cormorant populations in the future. Both African Penguins and Bank Cormorants no longer breed on the island and have therefore been removed from the IBA species list.
In addition to being affected by overfishing, Cape Gannet and African Penguin are susceptible to human disturbance. In the past, visitors to Bird Island disturbed birds at the edge of the colony and caused chicks to desert their nests. The area open to the public was fenced in 1974 and a high-tech viewing facility erected in 1998 has recently been upgraded by CapeNature. Visitors now rarely disturb seabirds.
Although it is thought that the causeway built from the mainland has had little effect on the island’s biota, several alien species have colonised the island. The house rat Rattus rattus has been present since 1966 and is thought to prey on Cape Cormorant eggs and scavenge nestlings and adults. Unfortunately, the causeway has meant that cats and dogs have open access to Bird Island and they regularly harm and eat birds.
An additional threat comes from Cape fur seals Arctocephalus pusillus, which kill Cape Gannet fledglings. This activity is mostly restricted to young, rogue male seals. The mortality rate for the gannets from this aberrant behaviour is between 11 and 15% of the population. A similar issue affects birds at Dyer Island (SA120), where the mortality rate is estimated to be higher. CapeNature officials are aware of this threat and specific rogue seals are occasionally culled if they kill gannet fledglings. In 2006, a higher than usual number of seals were involved and the killing or wounding of many birds caused the entire Cape Gannet colony to abandon the island. After the rogue seals responsible for the killing had been culled, conservation officials worked with a local artist to design a decoy that could be used to attract birds back to the island. This intervention proved successful and over the following weeks almost the entire colony of thousands of birds returned to Bird Island to begin breeding.
A similar threat has arisen in recent years from Kelp Gulls that feed on the eggs of Cape Gannets. CapeNature has been monitoring the situation since 2006 and a recent increase in the loss of gannet eggs to gulls has necessitated a strategic culling programme that targets rogue individuals involved in this behaviour.
Large sea swells have been known to occasionally wash birds and/or nests off the island. This is not a regular occurrence and does not represent a major threat to the bird colonies. Chronic pollution is a threat that is both unpredictable and difficult to control. It occurs when tankers break open, wash their tanks, dump cargo or pump bilge, resulting in the spillage of crude oil or other pollutants into the ocean. African Penguins are particularly susceptible to these events and a single oil disaster can severely affect populations.
Bird Island has been declared a CapeNature nature reserve and proclaimed as such under the NEM:PAA. The island therefore receives a high level of long-term, formal protection and management from the provincial conservation authority.
Simply designating a conservation area is often not enough, however, and Cape Nature officials actively manage this IBA to improve it for the birds. Their actions include the culling of rogue Cape fur seals and Kelp Gulls identified as individuals that prey on the birds. The culling is conducted in partnership with DEA: Oceans and Coasts Division and the low level required does not impact on the Cape fur seal population. Nesting posts with breeding platforms have been erected on the island to attract cormorants back to breed there.
These activities are part of the comprehensive Protected Area Management Plan developed by CapeNature for all its nature reserves. Reviews of individual management plans are held every five years and allow for public participation, including that of BirdLife South Africa, which is able to provide input to the plan and ensure that it takes the reserve’s avifauna into account. Recent upgrades to the tourism infrastructure at Bird Island include a bird hide and an interactive museum.
Adams NJ. 1991. Patterns and impacts of oiling of African Penguins Spheniscus demersus 1981–1991. Biological Conservation 68: 35–41.
Branch WR. 1991. The herpetofauna of the offshore islands of South Africa and Namibia. Annals of the Cape Provincial Museum (Natural History) 18: 205–225.
Broekhuysen GJ, Liversidge R, Rand RW. 1961. The South African Gannet Morus capensis 1. Distribution and movements. Ostrich 32: 1–19.
Brooke RK, Cooper J, Shelton PA, Crawford RJM. 1982. Taxonomy, distribution, population size, breeding and conservation of the White-breasted Cormorant, Phalacrocorax carbo on the southern African coast. Gerfaut 72: 189–220.
Brooke RK, Prins AJ. 1986. Review of alien species on South African offshore islands. South African Journal of Antarctic Research 16: 102–109.
Cooper J. 1981. Biology of the Bank Cormorant, Part 1: Distribution, population size, movements and conservation. Ostrich 52: 208–215.
Cooper J, Berruti A. 1989. The conservation status of South Africa’s continental and oceanic islands. In: Huntley, BJ (ed.), Biotic diversity in southern Africa: concepts and conservation. Cape Town: Oxford University Press. pp 239–253.
Cooper J, Brooke RK. 1986. Alien plants and animals on South African continental and oceanic islands: species richness, ecological impacts and management. In: Macdonald, IAW et al. (eds), The ecology & management of biological invasions in southern Africa. Cape Town: Oxford University Press.
Cooper J, Hockey PAR, Brooke RK. 1983. Introduced mammals on South and South West African islands: history, effects on birds and control. In: Cooper J (ed.), Proceedings of the Symposium on Birds of the Sea and Shore, 1979. Cape Town: African Seabird Group. pp 179–203.
Cooper J, Williams AJ, Britton PL. 1984. Distribution, population sizes and conservation of breeding seabirds in the Afrotropical region. ICBP Technical Publication No. 2.
Crawford RJM. 1995. Conservation of southern Africa’s breeding seabirds. Birding in Southern Africa 47: 106–109.
Crawford RJM, Boonstra HGvD, Dyer BM, Upfold L. 1995a. Recolonisation of Robben Island by African Penguins, 1983–1992. In: Dann P et al. (eds), The penguins. Australia: Surrey Beatty. pp 333–363.
Crawford RJM, Cooper J, Dyer BM. 1995b. Conservation of an increasing population of Great White Pelicans Pelecanus onocrotalus in South Africa’s Western Cape. South African Journal of Marine Science 15: 33–42.
Crawford RJM, Cooper J, Shelton, PA. 1982a. Distribution, population size, breeding and conservation of the Kelp Gull in southern Africa. Ostrich 53: 164–177.
Crawford RJM, David JHM, Williams AJ, Dyer BM. 1989. Competition for space: recolonising seals displace endangered, endemic seabirds off Namibia. Biological Conservation 48: 59–72.
Crawford RJM, Dyer BM. 1995. Responses by four seabird species to a fluctuating availability of Cape Anchovy Engraulis capensis off South Africa. Ibis 137: 329–339.
Crawford RJM, Dyer BM, Brooke RK. 1994. Breeding nomadism in southern African seabirds – constraints, causes and conservation. Ostrich 65: 231–246.
Crawford RJM, Dyer BM, Kotze PGH, McCue S, Meyer MA, Upfold L, Makhado AB. 2012. Status of seabirds breeding in South Africa in 2011. Cape Town: Department of Environmental Affairs, Branch Oceans & Coasts.
Crawford RJM, Shelton PA. 1978. Pelagic fish and seabirds interrelationships off the coasts of South West and South Africa. Biological Conservation 14: 85–109.
Crawford RJM, Shelton PA. 1981. Population trends for some southern African seabirds related to fish availability. In: Cooper J (ed.), Proceedings of the Symposium on Birds of the Sea and Shore, 1979. Cape Town: African Seabird Group. pp 15–41.
Crawford RJM, Shelton PA, Brooke RK, Cooper J. 1982b. Taxonomy, distribution, population size and conservation of the Crowned Cormorant Phalacrocorax coronatus. Gerfaut 72: 3–30.
Crawford RJM, Shelton PA, Cooper J, Brooke RK. 1983. Distribution, population size and conservation of the Cape Gannet Morus capensis. South African Journal of Marine Science 1: 153–174.
Crawford RJM, Williams AJ, Hofmeyer JH, Klages NTW, Randall RM, Cooper J, Dyer BM, Chesselet Y. 1995c. Trends in African Penguin Spheniscus demersus populations in the 20th century. South African Journal of Marine Science 16: 101–118.
Crawford RJM, Williams AJ, Randall RM, Randall RM, Berruti A, Ross GJB. 1990. Recent population trends in Jackass Penguins Spheniscus demersus. Biological Conservation 52: 229–243.
Frost PGH, Siegfried WR, Cooper J. 1976. Conservation of the Jackass Penguin (Spheniscus demersus). Biological Conservation 9: 79–99.
Furness RW, Cooper J. 1982. Interactions between breeding seabird and pelagic fish populations in the southern Benguela region. Marine Ecology Progress Series 8: 243–250.
Hockey PAR. 1983. The distribution, population size, movements and conservation of the African Black Oystercatcher Haematopus moquini. Biological Conservation 25: 233–262.
Hockey PAR, Hallinan J. 1981. Effects of human disturbance on the breeding of Jackass Penguins Spheniscus demersus. South African Journal of Wildlife Research 11: 59–62.
Jarvis MJF. 1971. Interactions between man and the South African Gannet Sula capensis. Ostrich suppl. 8: 497–513.
Jarvis MJF, Cram DL. 1971. Bird Island, Lambert’s Bay, South Africa: an attempt at conservation. Biological Conservation 3: 269–272.
Morant PD, Cooper J, Randall RM. 1981. The rehabilitation of oiled Jackass Penguins Spheniscus demersus, 1970–1980. In: Cooper J (ed.), Proceedings of the Symposium on Birds of the Sea and Shore, 1979. Cape Town: African Seabird Group. pp 267–301.
Randall RM, Randall BM, Bevan J. 1980. Oil pollution and penguins – is cleaning justified? Marine Pollution Bulletin 11: 234–237.
Shelton PA, Crawford RJM, Cooper J, Brooke RK. 1982. Distribution, population size and conservation of the Jackass Penguin Spheniscus demersus. South African Journal of Marine Science 2: 217–257.
Siegfried WR. 1982. Ecology of the Jackass Penguin Spheniscus demersus, with special reference to conservation of the species. National Geographic Society Research Reports 14: 597–600.
Summers RW, Cooper J. 1977. The population, ecology and conservation of the African Black Oystercatcher Haematopus moquini. Ostrich 48: 28–40.
Williams AJ. 1995. Lambert’s Bay Bird Island. In: Petersen W, Tripp M (eds), Birds of the south-western Cape and where to watch them. Cape Town: Southern Birds 20. SAOS and the Cape Bird Club. pp 128–131.
Wilson RP, Wilson MTP, Duffy DC. 1988. Contemporary and historical patterns of African Penguin Spheniscus demersus: distribution at sea. Estuarine, Coastal and Shelf Science 26: 447–458.