The status of the Damara Tern in the Eastern Cape, South Africa

Abstract

The Eastern Cape population of the Damara Tern Sternula balaenarum was estimated to be 25-29 pairs in the 2008/09 and 2009/10 breeding seasons. The population appears to be stable and has probably increased slightly since the early 1990s. An eastward shift of the majority of nest sites in the Alexandria dunefields of 5-10 km was recorded since the early 1990s. Breeding Damara Terns caught at night and colour-flagged in the Alexandria dunefields averaged 12% heavier than the average mass of birds handled in Namibia and egg masses ranged from 11% to 22% heavier than 21 fresh egg masses recorded in Namibia. Adult Damara Terns caught at night while incubating, were ringed and marked with coloured leg-flags. All chicks located were also ringed and leg-flagged. A stable isotope analysis of scapular feathers suggested that breeding adults from the Eastern Cape may moult in similar areas to the Namibian population, i.e. West Africa. Small numbers of Damara Terns were recorded during the winter in the Eastern Cape. Although these included no colour-flagged birds, the numbers of birds marked were probably too low to draw any definite conclusions regarding the origin of over-wintering Damara Terns.

Seabirds of the Benguela Ecosystem: Utilisation, Long-Term Changes and Challenges

“…In South Africa, in addition to shifts to the south and east of the three 'guanoproducing' seabirds reported in the previous section, there were decreased proportions of birds breeding in the north and increases in the south for Bank Cormorant P. neglectus, White-breasted Cormorant P. lucidus, Crowned Cormorant Microcarbo coronatus, Kelp Gull Larus dominicanus, Greater Crested (Swift) Tern Thalasseus bergii and Damara Tern Sternula balaenarum [29][30][31][32][33][34][35]. There is little or no competition by White-breasted and Crowned Cormorants, Kelp Gulls and Damara Terns with fisheries for forage resources [36], so environmental change may have influenced the redistributions of the seabirds [33].…”