Damara tern (Sterna balaenarum)
|French:||Sterne des baleiniers|
|Size||Length: 23 cm (2)|
|Weight||46 - 52 g (2) (3)|
Classified as Near Threatened (NT) on the IUCN Red List (1).
A typical small tern in appearance, the Damara tern has a white body, pale grey back, yellowish to dusky legs and a black beak. In breeding plumage the species has a black cap, which extends onto the nape (back of the neck), but outside of the breeding season this becomes more mottled grey-black, and the forehead turns white. Juveniles have a buff crown, a dark band through the eye and across the nape, grey flight feathers, and brown wing-coverts with dark edging (2) (4). Although quite similar in appearance to the little tern, Sterna albifrons, the Damara tern can be distinguished by a longer, slightly decurved beak, which does not turn yellow during the breeding season, as well as a paler grey back, and a stockier body shape (4) (5). The call of the Damara tern is a high-pitched tsit-tsit or a harsh, rapid kid-ick (4).
The Damara tern is found in its highest densities along the Namibian coastline, where an estimated 98 percent of the population nests (6), with smaller numbers occurring in South Africa and southern Angola. At the end of the breeding season the birds disperse north, being recorded along the coastal waters of Democratic Republic of the Congo, Congo, Gabon, Cameroon, Nigeria, Benin, Togo, Ghana, and Ivory Coast (2) (4).
The Damara tern breeds on gravel and stony plains, dunes and salt pans, up to three kilometres inland to avoid predators such as jackals that often frequent outer beaches (2). Feeding takes place in inshore waters of bays, estuaries, lagoons and salt pans, as well as in the surf zone (2) (6).
Hovering over the water before plunge-diving to catch its prey, the Damara tern feeds mainly on small fish, such as mullet and anchovy, and on small squid (2). Breeding occurs between late September and late February, but can extend to as late as May (3), with one, or rarely two, eggs being laid into a small scrape on open ground, the adult birds preferring locations that provide good visibility (4). The egg hatches after an incubation period of between 18 and 23 days, and the vulnerable chick is well camouflaged to match its surroundings, with white below and fawn above, speckled with black. The chick leaves the nest at just two days old, crouching motionless to blend in with its surroundings and so avoid detection by predators. Fledging occurs around 20 days later, but the chick is dependent on the adult birds for another two and a half months (2) (3) (4).
The Damara tern’s feeding areas are under threat from dredging, land reclamation and hotel construction (2) (4), while its breeding sites are threatened by human disturbance, in the form of off-road vehicles, which can destroy nests, and other human activity on beaches, particularly as this often coincides with the species’ breeding season (4). One of the largest known breeding colonies, Caution Reef, south of Swakopmund in Namibia, currently suffers considerable human disturbance (4), which has been found to reduce breeding success (6). Large-scale mining operations have also caused some disturbance, affecting feeding due to sediment discharge causing increased water turbidity (3).
The Damara tern is listed under Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMS), which aims to conserve migratory species throughout their range (7). It is also listed under the associated Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA), which calls upon parties to engage in a range of conservation actions to help protect and conserve bird species that are dependent on wetlands for at least part of their annual cycle (8). Other proposed conservation measures include protecting breeding sites from development, pollution and human disturbance, and creating ‘disturbance-free’ areas on nesting beaches (4). An example of one such successful measure is at the Damara tern’s breeding site at Caution Reef, Namibia, where the use of information boards and barriers to exclude off-road vehicles has resulted in a doubling of the number of chicks successfully hatched (6).
As a result of its habit of nesting in loose colonies in some fairly remote areas of the Namib Desert coastline, the Damara tern has proved difficult to count and study in the past (9). The global population is believed to be fairly small, but further monitoring may be needed to identify any population trends. If found to be undergoing a decline, the Damara tern may qualify for upgrading to a higher threat category on the IUCN Red List in the future (4).
For more information on the conservation of migratory waterbirds, see:
African-Eurasian Waterbird Agreement:
For more information on the conservation of coastal habitats and species in Namibia, see:
Namibian Coast Conservation and Management project (NACOMA):
For more information on this and other bird species please see:
- BirdLife International:
Authenticated (29/06/09) by Justine Braby, PhD Student, Animal Demography Unit, Department of Zoology, University of Cape Town.
- Coverts: small feathers concealing the bases of larger flight feathers, usually on the wings or tail.
- Flight feathers: the feathers at the end of the wing, involved in flight.
- Incubation: the act of incubating eggs; that is, keeping them warm so that development is possible.
IUCN Red List (July, 2014)