Giant ibis  (Thaumatibis gigantea)

This huge ibis has a large, curved bill and a distinctive repeated, loud, ringing call sounding like ‘a-leurk a-leurk', mainly used at dawn and dusk. The adult is dark with a naked, grey head and upper neck. There are dark bands across the back of the head and shoulder area and the pale silvery-grey wing tips also have black crossbars. The beak is yellowish-brown, the legs are orange, and the eyes are dark red. Juveniles have short black feathers on the back of the head down to the neck. Their bills are shorter and their eyes are brown (2).

With a remaining population of fewer than 250 birds, the giant ibis is found only in northern Cambodia and the extreme southern tip of Laos. It was previously found in southern Vietnam and southeast and peninsular Thailand, but is now extinct in these countries (2).

Primarily inhabits the northern Cambodian open dipterocarp forest. This bird feeds in wetlands (more abundant during the rainy season) but also in the grasslands during the dry season (3).

With so few birds remaining, and no current research projects focussing on this species, not much is known of the breeding biology of the giant ibis. It is thought to nest in trees, and is known to wander widely in response to seasonal water-levels and human disturbance. Individuals, pairs or small groups of birds feed together, probing into soft mud, or foraging on dry land during the dry season. They consume mainly invertebrates, particularly locusts and cicadas, as well as crustaceans, small amphibians, small reptiles (2), and seeds (4).

Continuing deforestation and wetland drainage for agriculture has led to widespread habitat loss for the giant ibis, although much suitable but unoccupied habitat still remains. This suggests that hunting and human disturbance may be the most serious threats to the giant ibis (2).

The giant ibis gains official protection from its presence in Xe Pian National Biodiversity Area in Laos, and in Lomphat Wildlife Sanctuary, Cambodia. Both Laos and Cambodia are running a campaign to reduce the hunting of large water birds and the giant ibis is illustrated on public awareness material. Surveys to monitor the giant ibis' population and distribution have been proposed, as well as research to discover their breeding habits and requirements (2). The creation of further protected areas has been recommended (2), and captive breeding will be considered. Crucially, gun ownership must be further controlled, following the success of such schemes in Laos (4).

For further information on the giant ibis see:

• BirdLife International. (2001) Threatened Birds of Asia: the BirdLife International Red Data Book. BirdLife International, Cambridge, UK.

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