Behaviour Adults of this species are mostly sedentary, although some seasonal movement occurs between breeding and non-breeding habitats⁴, within a 15km range⁵. Breeding occurs from September to April, with a peak from November to February^3,4. It breeds slightly later in Namibia than in South Africa^3,4. Juveniles either disperse at independence, moving up to 150km from their natal site to areas with high adult density^3,4, or migrate up to 2000km to one of five nursery areas⁴. These return to their natal area after 2-3 years⁴. The species breeds and forages solitarily^4,5,but roosts communally in groups of up to 200 in the non-breeding season^4,5. Habitat Breeding Offshore islands and sandy beaches are favoured as breeding habitats⁴. It rarely breeds on mainland rocky shores^4,5. Non-breeding The species forages exclusively in the intertidal zone^4,5 and is found on mainland rocky and sandy shores during the non-breeding season, being less frequent in estuaries, lagoons and coastal pans^3,4. It tends to roost on promontaries with good all-round visibility⁴. Nurseries occur in both sheltered bays and open rocky shores⁴. Diet Its diet includes primarily bivalves such as limpets and mussels, but also polychaetes, whelks and crustaceans^3,4,5. Breeding site The nest is a scrape in sand where possible, but on rocky subtrata shells are built up to form a lip^3,4,5, or eggs are laid on bare rock^3,4. The nest is usually situated within 30m of the high water mark^4,6, often beside a disruptive object such as a rock or clumps of kelp^4,8. The clutch-size ranges from one to three eggs, but is usually two. The incubation period is 27-39 days, followed by a fledging period of 35-40 days; pairs rear one or two chicks. Fledging success is 0.3-0.6 young per pair per year on predator-free offshore islands, but is lower on the mainland. There is evidence that breeding productivity has increased on the west coast since 1980, following the invasion of the Mediterranean mussel Mytilus galloprovincialis. Age of first breeding is three years in females, and probably four years in males. The species is known to live for over 18 years³.

Red List Category

Red List Criteria

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Justification

History

• 2006
  Near Threatened
• 2004
  Near Threatened
• 1988
  Near Threatened

The population is estimated at 5,000-6,000 individuals (T. Dodman in litt. 2002 to Wetlands International 2002).

The peak of the breeding season coincides with peak coastal recreational activities and the resulting disturbance reduces breeding success⁷. Off-road vehicles are a particular problem, as they churn up beaches, run over nests and crush eggs, and kill young hiding in vehicle tracks. In addition, people on beaches can keep adults off nests for extended periods, overheating eggs and killing embryos, and predation of eggs and chicks by domestic dogs can be a problem⁷. Disturbance also leads to the predation of eggs and chicks by Kelp Gulls Larus dominicanus⁸. On sections of the coastline undisturbed by humans, natural predators (e.g. mongoose) take many nests. The mainland is likely to prove a population sink for surplus birds from near-shore islands, with breeding productivity too low to sustain coastal populations. Coastal development is thought to have caused declines in some areas³. The c.30% of the total population that is found on offshore islands is threatened by the introduction of mammalian predators³.

Conservation Actions Underway
On most near-shore islands, population sizes have been stable or increased recently due to either improved management, e.g. the cessation of guano-scraping during the 1980s, and/or a change in diet from indigenous limpets and mussels to invasive mussels such as Mytilus galloprovincialis (e.g. at Robben Island, South Africa)¹. Recreational vehicles have been banned from the Overberg coast since February 2002⁸. The national Oystercatcher Conservation Programme (OCP) has been raising public awareness concerning the species and its needs, and has been generating local community involvement it its conservation⁸.

Conservation Actions Proposed
Monitor population trends and annual breeding success. Study local rates of predation. Create disturbance-free areas on beaches. Protect areas of coastal habitat. Design measures to prevent the introduction of mammalian predators to breeding islands.