The Damara tern (Sternula balaenarum) is a small seabird belonging to the family Laridae, which includes gulls, terns, and skimmers. It is one of the smallest tern species and is endemic to the southern African coastline.
Taxonomy and Etymology
The Damara tern was first described by Swedish zoologist Johan August Wahlberg in 1892. Its scientific name, Sternula balaenarum, translates roughly to "little tern of whales," potentially referring to its coastal habitat where whales might also be found. It is part of the Sternula genus, which comprises several species of small terns often referred to as "little terns" or "fairy terns."
Description
The Damara tern is a tiny, delicate tern, typically measuring about 23 cm (9 inches) in length with a wingspan of approximately 44 cm (17 inches) and weighing around 60-70 grams. Adults in breeding plumage exhibit a pale grey back and wings, with white underparts. Their most distinctive features include a black cap extending down to the nape, a prominent white forehead, and a small, slender black bill. The legs are dark grey to black. In non-breeding plumage, the black cap becomes mottled with white, and the white forehead becomes less distinct, blending more into the cap. Juveniles resemble non-breeding adults but may have some dusky markings on their upperparts and a less defined cap.
Habitat and Distribution
The Damara tern is a coastal species, primarily found along the arid and semi-arid coastlines of southwestern Africa. Its breeding range extends from central Angola southwards through Namibia to the Western Cape province of South Africa. It prefers sandy or gravelly beaches, salt pans, and estuarine mudflats for nesting, often choosing areas with sparse vegetation or open, undisturbed stretches of sand. During the non-breeding season, these terns disperse somewhat, but generally remain within the Benguela current region, occasionally recorded further north along the Angolan coast or even to the Congo. They are strictly marine birds, rarely venturing far inland.
Diet and Foraging
The diet of the Damara tern consists almost exclusively of small fish, particularly larval and juvenile fish species, which they catch by plunge-diving from a low height or by surface-skimming. They typically forage in shallow coastal waters, estuaries, and lagoons, often in areas where upwellings bring nutrients and small fish close to the surface. Their foraging strategy involves hovering briefly before diving head-first into the water to snatch their prey. Insects may occasionally supplement their diet, especially when foraging near estuaries or tidal pools.
Breeding
Damara terns are ground-nesting birds, typically breeding in loose colonies or as solitary pairs. The breeding season usually runs from November to March, coinciding with the austral summer. They construct a simple scrape in the sand, often in areas with small pebbles or shell fragments, which helps camouflage the nest. Typically, one or two (rarely three) eggs are laid. The eggs are cryptically coloured, usually pale grey or buff with dark spots, blending in well with the surroundings. Both parents share incubation duties, which last about 18-22 days. The chicks are precocial, meaning they are covered in down and able to move shortly after hatching. Fledging occurs after approximately 18-20 days, but the young remain dependent on their parents for food for some time thereafter. Breeding success is highly dependent on undisturbed nesting sites and adequate food availability.
Conservation Status and Threats
The Damara tern is classified as Near Threatened by the International Union for Conservation of Nature (IUCN). Its population is relatively small, estimated to be between 10,000 and 20,000 mature individuals, and is thought to be undergoing a slow decline. The primary threats to the Damara tern include:
- Habitat Loss and Degradation: Coastal development, mining activities (especially for diamonds), tourism, and human disturbance (such as off-road vehicles) destroy or degrade their critical nesting habitats.
- Predation: Eggs and chicks are vulnerable to predation by natural predators like gulls, jackals, and raptors, as well as introduced predators like domestic cats and dogs.
- Climate Change: Changes in ocean currents, prey availability, and increased frequency of extreme weather events (e.g., storms and high tides) can impact breeding success and survival.
- Oil Spills and Pollution: As a coastal species, they are susceptible to the impacts of marine pollution, including oil spills.
Conservation efforts focus on protecting key breeding sites through the establishment of protected areas, monitoring populations, reducing human disturbance, and managing predator control where necessary.