Chlidonias hybrida (Whiskered tern) 

Witbaardsterretjie [Afrikaans]; Witwangstern [Dutch]; Guifette moustac [French]; Weißbart-seeschwalbe [German]; Gaivina-de-faces-brancas [Portuguese]

Life > Eukaryotes > Opisthokonta > Metazoa (animals) > Bilateria > Deuterostomia > Chordata > Craniata > Vertebrata (vertebrates)  > Gnathostomata (jawed vertebrates) > Teleostomi (teleost fish) > Osteichthyes (bony fish) > Class: Sarcopterygii (lobe-finned fish) > Stegocephalia (terrestrial vertebrates) > Tetrapoda (four-legged vertebrates) > Reptiliomorpha > Amniota > Reptilia (reptiles) > Romeriida > Diapsida > Archosauromorpha > Archosauria > Dinosauria (dinosaurs) > Saurischia > Theropoda (bipedal predatory dinosaurs) > Coelurosauria > Maniraptora > Aves (birds) > Order: Charadriiformes > Family: Laridae  > Genus: Chlidonias

Chlidonias hybrida (Whiskered tern)

Whiskered tern in non-breeding plumage, Gauteng. [photo Gerhard Theron ©]

Chlidonias hybrida (Whiskered tern)  Chlidonias hybrida (Whiskered tern)

Whiskered tern in breeding plumage. [photo Callie de Wet ©]

Whiskered tern in breeding plumage, Gauteng. [photo Gerhard Theron ©]

Distribution and habitat

Occurs discontinuously from western Europe to eastern China and Russia south to Australia and sub-Saharan Africa, where it is largely absent from the lowland forest of the DRC and West Africa. Here it is locally fairly common in northern Namibia (including the Caprivi Strip), northern and eastern Botswana, western and southern Zimbabwe, southern Mozambique and central and south-western South Africa. It generally prefers natural wetlands, especially vleis, marshes and river flood plains with emergent vegetation, mainly breeding on temporary marshes and farm dams.

Distribution of Whiskered tern in southern Africa, based on statistical smoothing of the records from first SA Bird Atlas Project (© Animal Demography unit, University of Cape Town; smoothing by Birgit Erni and Francesca Little). Colours range from dark blue (most common) through to yellow (least common). See here for the latest distribution from the SABAP2.  

Predators and parasites

Movements and migrations

Breeding summer migrant to north-central Namibia, Zimbabwe, the South African highveld, the Western Cape and the Eastern Cape. It is largely resident in Botswana, north-western Zimbabwe and the tropical lowlands of Mozambique and KwaZulu-Natal.

Food 

It mainly eats small fish, amphibians including Arum lily frogs (Hyperolius horstockii) plucked from Arum lilies (Zantedeschia aethiopica), insects and other invertebrates. It does most of its foraging in loose flocks, flying up wind, 2-4 metres above water.

Breeding

  • Monogamous colonial nester, breeding in colonies of 5-30, rarely 60-80 pairs spread 2-20 metres apart. It is an opportunistic breeder, with laying dates often synchronised within the colony, as they all lay straight after heavy rain.
  • The nest (see image below) is built by both sexes, consisting of an untidy floating structure of plant stems, leaves and sometimes grass, which an be either flat or higher and more bulky depending on environmental conditions.
Chlidonias hybrida (Whiskered tern) Chlidonias hybrida (Whiskered tern)

Whiskered tern at its nest with chicks, Wakkerstroom, South Africa. [photo Warwick Tarboton ©]

Close-up of Whiskered tern chick, Wakkerstroom, South Africa. [photo Warwick Tarboton ©]

  • Egg-laying season is from October-April, peaking from January-March in most of southern Africa excluding the Western Cape, where egg-laying is mainly from October-February, peaking from October-November.
  • It lays 1-3 eggs, which are incubated by both sexes for about 20 days.
  • The chicks can swim soon after hatching, taking to the water if predators before returning once the danger passes. The adults are aggressive in defence of their young, often attacking and dive bombing intruders such as humans. They fledge at about 20-27 days old, soon after which they start to practice foraging, although still regularly returning to the nest to be fed.

Threats

Not threatened, although cattle can be a major breeding disturbance, often causing the abandonment of nests by breeding pairs.

References

  • Hockey PAR, Dean WRJ and Ryan PG 2005. Roberts - Birds of southern Africa, VIIth ed. The Trustees of the John Voelcker Bird Book Fund, Cape Town. 

 

 

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