Breeding biology of the White-fronted Plover (Charadrius marginatus) in the south-western cape, South Africa

Summary

A small breeding population of White-fronted Plovers Charadrius marginatus was studied at Langebaan Lagoon, South Africa, between 1974 and 1977. Adults maintained territories throughout the year though territory holders sometimes joined flocks of non-territorial birds, usually outside the breeding season. Territories included sections of sand dune and beach where nests were located, and an area of intertidal sand flat where the birds fed. The species is monogamous and mates are usually faithful to each other for long periods. Divorce was recorded and two birds whose mates disappeared, presumed dead, did not lose their territories. Eggs were found between June and January (eight months). A minimum of two to four days elapsed between the laying of the first and second egg. The mean clutch size was 2·1 eggs and the most frequent clutch was two. Incubating birds moulted some tertials, tail and body feathers. Incubation was shared by the sexes and lasted 26 or 27 days (one record). Breeding success was low, and is believed to be due to predation of eggs by mongooses and Bokmakierie shrikes. Two pairs each produced a minimum of five clutches in one season. The presence of roosting and feeding flocks of non-territorial plovers was tolerated when the flooding tide forced these birds into the territories of breeding birds. The annual survival rate of adults with territories was 0·8757 and the average expectation of further life was 7·5 years. Aspects of the breeding biology of White-fronted and Ringed Plovers are compared. It is suggested that the high predation rate of eggs may have influenced the evolution towards a relatively small clutch.