Giant Ibis
(Thaumatibis gigantea)
The Giant Ibis is a huge, striking ibis, unique by virtue of its being the largest member its family. This species is Cambodia’s national bird, and owing to its rarity and exceptional size holds near-mythical status for bird-watchers, naturalists and conservationists. This species’ range is now much reduced; having historically inhabited vast areas of mainland south-east Asia, the Giant Ibis now has an extremely small, declining population, concentrated in Cambodia. It also occurs in extreme southern Laos and has been sighted in Vietnam. Already extinct in Thailand, it is thought to be on the verge of extinction in other localities within its current range. It has been classified as critically endangered based on the likelihood of continued decline, predominantly due to the effects of human disturbance and hunting.
Urgent Conservation Actions
Accurate measure of population size, research into bird movements and juvenile survival, protection of nesting sites and development of education and public awareness campaigns.
Northern Cambodia and extreme southern Laos. A sighting was also recorded in Vietnam in 2004.
Weighing in at a staggering 4,200g, the Giant Ibis is the largest of all the world’s ibises.
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Media from ARKive
Arkive video - Giant ibis - overview
Arkive image - Giant ibis
Arkive image - Giant ibis at a temporary waterhole
Arkive video - Giant ibis adults and chick at nest
Arkive video - Giant ibis chick begging for food, adult feeds it
Arkive image - Giant ibises at a temporary waterhole
Arkive image - Giant ibis at water
Arkive video - Giant ibis feeding
Arkive image - Giant ibis feeding
Arkive video - Giant ibis - feeding
Arkive image - Group of giant ibis at waterhole, foraging
Arkive image - Giant ibises in habitat
Evolutionary Distinctiveness
Order: Ciconiiformes
Family: Threskiornithidae
The order Ciconiiformes comprises the wading birds, and traditionally grouped together the flamingos, ibises, spoonbills, herons and storks. Members of this clade are under debate, but it is believed that the family Threskiornithidae should remain within this order. The family has 34 members, which are split into the ibises and spoonbills. The large size of the Giant Ibis makes it unique among the Threskiornithidae. At one time this species was considered to be most closely related to the Red-naped Ibis (Pseudibis papillosa), and was assigned to the Pseudibis genus accordingly. However, recent studies advise against removing this distinctive ibis from its specialised genus without further anatomical study. The Giant Ibis is the sole representative of the monotypic genus Thaumatibis.
The tree below shows the evolutionary relationships between this species and all other birds. The colours of the tree indicate EDGE scores with the red shades indicating the higher priority species; the bright red leaves correspond to the top 100 EDGE bird species. Further information on every species can be found by zooming in to its leaf on the tree.
Weight: 4,200g
The Giant Ibis is a huge bird. The head and neck of the adult are bald, the skin being grey in colour. It possesses a long, down-curved, yellow-brown beak and red eyes. Across the nape of the neck and shoulders, there are narrow dark bands, whilst the secondary feathers on the body have silvery grey tips with black cross bars. The strong legs are orange. The juvenile differs from the adult in that it has a shorter beak, brown eyes and black feathers on the back of the head. It can be identified from its call, which makes an ‘a-leurk, a-leurk’ ringing sound which is typically heard at dawn and dusk.

The Giant Ibis has a varied diet consisting of invertebrates (particularly locusts and cicadas), crustaceans, small amphibians and reptiles, and seeds. It forages using its long, curved bill to probe into cracks and feel for food deep in the mud or water. Slit-like nostrils are situated at the base of the bill allowing continued breathing whilst the bird’s bill is submerged. In flight, the bird stays low, seldom rising above the tree canopy. Like all ibises, this species is diurnal and prefers to feed in damp substrates, relying on the soft mud around seasonal pools (known as ‘trapeangs’ in Khmer) to survive. These pools are often dug by large animals such as water buffalo.  In response to local disturbance and seasonal water-level changes, the bird will range widely to find its preferred feeding conditions. In the absence of damp, submerged habitats, the bird will forage in dry areas. A shy bird, this species nests in trees, often more than 5km from human habitation. They live in singles, pairs or small groups and tend to nest away from villages in deciduous forests located close to grassland and pools.

This ibis is found in the lowlands, living in swamps, marshes, paddy-fields, open wooded plains, humid clearings, and pools within deciduous dipterocarp lowland forest. It is also found along wide rivers.
The Giant Ibis is predominantly found in northern and north-eastern Cambodia, where it has a large range, but is relatively rare. A tiny population also persists in the extreme southern tip of Laos and in 2004 a sighting was also reported in Yok Don National Park, Vietnam. Historically, the species inhabited vast ranges throughout mainland South-East Asia, but it is now extinct in Thailand, where the last sighting occurred in 1913.
Population Estimate
230 pairs
Population Trend
Critically Endangered

The decline of the species is primarily due to destruction of habitat, human disturbance and possibly hunting. Wetlands are being drained for agriculture and lowland deciduous dipterocarp forests are being cleared to make way for rubber, sugar cane, cassava and teak plantations. The Giant Ibis is sensitive to human presence. This becomes a problem in the dry season when humans gather at available watering holes, discouraging the ibises from using them. Disturbance at feeding sites, agricultural expansion and hunting, as well as loss of breeding habitat, all contribute to the shrinking population. Recent studies also suggest that nest predation by mammalian carnivores, such as the common palm civet and yellow-throated marten, may be having a huge impact on the Giant Ibis population.  A decline in the number of large grazing animals, particularly wild water buffalo, has also been cause for concern, as these birds rely on the pools and wallows dug by the buffalo as feeding sites.

Conservation Underway
In Cambodia, the highest density populations are found in northern Cambodia (especially the Preah Vihear Protected Forest) and north-eastern Cambodia (e.g. Western Siem Pang); whilst smaller populations are found in other conservation areas within the same landscapes (Kulen Promtep Wildlife Sanctuary in northern Cambodia, and Lomphat Wildlife Sanctuary and the Mondulkiri Protected Forest in north-eastern Cambodia). Efforts are underway by the Wildlife Conservation Society (WCS), BirdLife International and the World Wide Fund for Nature (WWF) to establish these conservation areas. Nests of Giant Ibis are located and fitted with anti-predator belts as recommended by Keo et al. (2009). Campaigns in Cambodia are underway to increase awareness about the plight of this iconic bird. The Wildlife Conservation Society and the Sam Veasna Centre for Wildlife Conservation (SVC) have established an ibis ecotourism project at Tmatboey in Kulen Promtep Wildlife Sanctuary. This seems to be proving effective in engaging local communities in conservation and supporting their development by providing them with income from visiting tourists. In Laos, the species can be found (seasonally) in one National Biodiversity Conservation Area (NBCA) and one proposed NBCA.
Conservation Proposed
A study in 2008 by Dr. Omaliss Keo outlined several conservation issues to be addressed. The location of all the feeding and breeding grounds need to be identified and then protected. Many of the seasonal wetlands and pools that the Giant Ibis uses are not currently protected – this is something that needs to be rectified as a matter of urgency. Known and potential nesting trees need to be fitted with anti-predator belts and prey animal abundance needs to be monitored, particularly in the dry season. Further research on breeding season habitat use needs to be undertaken, as does that on juvenile survival rates. The movement of birds outside protected areas also needs to be recorded using satellite telemetry and an accurate population size needs to be calculated. Further steps in terms of public and government engagement need to be made, particularly across northern and north-eastern Cambodia, where the bird is resident. Ecotourism that provides jobs for local communities also needs to be encouraged.
Anon. 2003. Endangered species rediscovered in Yok Don National Park, Dak Lak province. The Babbler: BirdLife in Indochina 2(2): 12-13.

Arkive (2013) Giant ibis (Thaumatibis gigantea) facts. Downloaded from www.Arkive.org on 22/01/2013

BirdLife International (2013) Species factsheet: Thaumatibis gigantea. Downloaded from http://www.birdlife.org on 22/01/2013.

BirdLife International (2012) Thaumatibis gigantea. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. www.iucnredlist.org. Downloaded on 22 January 2013.

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

del Hoyo, J., Elliott, A. and Sargatal, J. eds. (1992). Handbook of the Birds of the World. Vol. 1. Barcelona: Lynx Edicions. 72-506.

Eames, J. C., Nguyen Duc Tu, Le Trong Trai, Dang Ngoc Can, Ngo Van Tri, Hoang Duc Dat, Thai Ngoc Tri & Nguyen Thi Thu He (2004) Final biodiversity report for Yok Don National Park, Dak Lak Province, Vietnam: Creating protected areas for resource conservation using landscape ecology (PARC) Project VIE/95/G31&031. Government of Vietnam (FPD)/UNOPS/UNDP/Scott Wilson Asia-Pacific Ltd./ Environment and Development Group and Forest Renewable Resources Ltd., Hanoi.

Keo, O. (2008a) Ecology and conservation of the Giant Ibis Thaumatibis gigantea in Cambodia. BirdingASIA 9: 100-106.

Keo, O. (2008b) Ecology and conservation of Giant Ibis in Cambodia. PhD Thesis. University of East Anglia, UK.

Keo, O., Collar, N. J. and Sutherland, W. J. (2009) Nest protectors provide a cost-effective means of increasing breeding success in Giant Ibis Thaumatibis gigantea. Bird Conservation International 19(1): 77-82.
Text compiled by Michelle Harrison. Factchecked by Tom Clements.

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