DISTRIBUTION, POPULATION-SIZE AND CONSERVATION OF THE SWIFT TERN STERNA-BERGII IN SOUTHERN AFRICA

The Swift Tern Srerna bergii occurs commonly in coastal southern Africa, with a nonbreeding distribution extending the length of the southern African coast and into southern Angola. The known nonbreeding distribution of the nominate subspecies S. b. bergii extends from Swakomund, Namibia to Kosi Bay, Natal, South Africa. In Natal its nonbreeding distribution overlaps with that of the subspecies S. b. enigma. The species very rarely occurs inland or far out to sea. The breeding distribution of the nominate subspecies extends from Swakopmund to Algoa Bay, eastern Cape, South Africa. Twenty-two breeding localities are known in southern Africa, but usually only six to seven are occupied. in any one year. Most breeding localities are marine islands where Swift Terns often breed in muted colonies with Hartlaub’s Gulls Lorus hartloubii. In 1984 a complete breeding census estimated a breeding population of 4835 pairs. However, 6088 pairs were counted at only three localities in 1988. The size of the annual breeding population varies by a factor of as much as 1, 6; although the overall size of the adult population is thought to be reasonably stable with no temporal trends evident. Thirteen breeding localities which are legally proclaimed nature reserves supported 72% of the 1984 breeding population. Existing and perceived threats to the Swift Tern are discussed in detail. To improve further the conservation status of the Swift Tern in southern Africa, it is recommended that: Unprotected breeding localities be proclaimed reserves, also protecting those not on islands with adequate fences; feral cats be removed from breeding islands where they are present; and fisherman be educated to release entangled terns and not to discard lines and nets. © 1990 Taylor and Francis Group, LLC.