Giant Ibis Pseudibis gigantea Scientific name definitions

102–106 cm; c. 3515 g (one male) (1 Round, P. D. (1988). Resident Forest Birds in Thailand: their Status and Conservation. Monograph 2. International Council for Bird Preservation, Cambridge, UK. Close ). Unmistakable due to large size . Upperwing-coverts mainly silvery grey  , contrasting with darker body and flight-feathers. Narrow black stripes  across nape. Pseudibis davisoni is smaller and uniformly darker with whitish collar and white patch on inner wing-coverts. Juvenile has short grey feathers on hindcrown and hindneck, lacking dark bands on these plumage tracts; also has shorter bill and brown or blackish eyes (dark red in adults).

Once widespread in Indochina, range now much reduced; mostly confined to N Cambodia and extreme S Laos; recently recorded in Vietnam (2 Anon. (2003). Endangered species rediscovered in Yok Don National Park, Dak Lak province. The Babbler: BirdLife in Indochina 2(2): 12–13. Close ). Extinct in Thailand (3 BirdLife International (2013). IUCN Red List for birds. URL: http://www.birdlife.org (download Aug 2013). Close ).

Lowlands , occurring in lakes, swamps, seasonally flooded marshes, paddyfields (although recent study in Cambodia found no evidence of species using such habitats) (4 Wright, H.L., Collar, N.J., Lake, I.R., Vorsak, B. and Dolman, P.M. (2012). Foraging ecology of sympatric White-shouldered Ibis Pseudibis davisoni and Giant Ibis Thaumatibis gigantea in northern Cambodia. Forktail. 28: 93–100. Close ), wooded plains with patches of grassland (veals, many of which originate from historic rice cultivation, but the sward is typically taller than at recently abandoned paddies) (4 Wright, H.L., Collar, N.J., Lake, I.R., Vorsak, B. and Dolman, P.M. (2012). Foraging ecology of sympatric White-shouldered Ibis Pseudibis davisoni and Giant Ibis Thaumatibis gigantea in northern Cambodia. Forktail. 28: 93–100. Close ), humid clearings and pools (trapaengs) in deep semi-evergreen and dry dipterocarp forest. Compared to P. davisoni, present species is generally found at greater distances from human settlements throughout the year (9·9 km versus 8·3 km) (4 Wright, H.L., Collar, N.J., Lake, I.R., Vorsak, B. and Dolman, P.M. (2012). Foraging ecology of sympatric White-shouldered Ibis Pseudibis davisoni and Giant Ibis Thaumatibis gigantea in northern Cambodia. Forktail. 28: 93–100. Close ). Congregates at permanent waterholes during droughts (although trapaengs are also important in the wet season) and has been recorded using river channels during dry season (4 Wright, H.L., Collar, N.J., Lake, I.R., Vorsak, B. and Dolman, P.M. (2012). Foraging ecology of sympatric White-shouldered Ibis Pseudibis davisoni and Giant Ibis Thaumatibis gigantea in northern Cambodia. Forktail. 28: 93–100. Close ).

Presumably sedentary and largely resident, but apparently wanders widely in response to local disturbance and seasonal water-levels; records from peninsular Thailand in late 19th and early 20th centuries may have referred to migrants or vagrants.

Until recently, almost nothing known, but now subject to several studies in Cambodia. Stomach contents of one bird contained many crabs, but was also thought to consume locusts, cicadas and seeds (5 Thewlis, R.M. and Timmins, R.J. (1996). The rediscovery of Giant Ibis Pseudibis gigantea with a review of previous records. Bird Conservation International. 6(4): 317–324. Close ); however, initial study in Cambodia revealed that frogs (50% of all identified prey items) were particularly important (perhaps only later in dry season) (4 Wright, H.L., Collar, N.J., Lake, I.R., Vorsak, B. and Dolman, P.M. (2012). Foraging ecology of sympatric White-shouldered Ibis Pseudibis davisoni and Giant Ibis Thaumatibis gigantea in northern Cambodia. Forktail. 28: 93–100. Close ), followed by insects, mole-crickets and larvae, with eels constituting 3·5% of prey captured (6 Keo, O. (2008). Ecology and conservation of the Giant Ibis Thaumatibis gigantea in Cambodia. BirdingASIA. 9: 100–106. Close ), while crabs (4 Wright, H.L., Collar, N.J., Lake, I.R., Vorsak, B. and Dolman, P.M. (2012). Foraging ecology of sympatric White-shouldered Ibis Pseudibis davisoni and Giant Ibis Thaumatibis gigantea in northern Cambodia. Forktail. 28: 93–100. Close ) and fish also form part of diet (7 Eames, J.C. (2011). Feeding ecology of Giant Ibis Thaumatibis gigantea, Stung Treng province, Cambodia. BirdingASIA. 16: 98–100. Close ). The presence of frogs and mole-crickets appear to be the main driver in feeding habitat selection in the non-breeding season (6 Keo, O. (2008). Ecology and conservation of the Giant Ibis Thaumatibis gigantea in Cambodia. BirdingASIA. 9: 100–106. Close ). Probes with bill slightly agape (7 Eames, J.C. (2011). Feeding ecology of Giant Ibis Thaumatibis gigantea, Stung Treng province, Cambodia. BirdingASIA. 16: 98–100. Close ). Feeds  in pairs  or small flocks (up to 5–7 birds) (7 Eames, J.C. (2011). Feeding ecology of Giant Ibis Thaumatibis gigantea, Stung Treng province, Cambodia. BirdingASIA. 16: 98–100. Close ) in short wet grass (where searches for frogs, mole-crickets, insects and larvae) and shallow pools with extensive muddy fringes (with eels the main prey), usually relatively distant from villages, although this is perhaps as much due to the greater prevalence of frog and eel hunting near villages than direct human disturbance, while pools near villages are often partially drained for fishing, causing them to dry out quicker (6 Keo, O. (2008). Ecology and conservation of the Giant Ibis Thaumatibis gigantea in Cambodia. BirdingASIA. 9: 100–106. Close ). Compared to P. davisoni, which seems to prefer dry substrates for foraging, present species appears to shun such areas, although both species feed at the same waterholes with T. gigantea selecting prey with greater biomass (4 Wright, H.L., Collar, N.J., Lake, I.R., Vorsak, B. and Dolman, P.M. (2012). Foraging ecology of sympatric White-shouldered Ibis Pseudibis davisoni and Giant Ibis Thaumatibis gigantea in northern Cambodia. Forktail. 28: 93–100. Close ). Sometimes forages belly-deep in water (7 Eames, J.C. (2011). Feeding ecology of Giant Ibis Thaumatibis gigantea, Stung Treng province, Cambodia. BirdingASIA. 16: 98–100. Close ). In dry season, this species and P. davisoni are harassed by kleptoparasites such as Little Egret (Egretta garzetta), Chinese Pond-heron (Ardeola bacchus) and Ciconia episcopus (7 Eames, J.C. (2011). Feeding ecology of Giant Ibis Thaumatibis gigantea, Stung Treng province, Cambodia. BirdingASIA. 16: 98–100. Close ); more rarely Brahminy Kite (Haliastur indus) also attempts to steal food from T. gigantea (7 Eames, J.C. (2011). Feeding ecology of Giant Ibis Thaumatibis gigantea, Stung Treng province, Cambodia. BirdingASIA. 16: 98–100. Close ).

Repeated, loud  , ringing “a-leurk a-leurk” at dawn and dusk.

Until recently nothing was known concerning this species’ breeding ecology, but in recent years many nests have been found and studied, including 27 and 26 sites in 2004 and 2005, respectively, with 13 nests being used in both seasons (6 Keo, O. (2008). Ecology and conservation of the Giant Ibis Thaumatibis gigantea in Cambodia. BirdingASIA. 9: 100–106. Close ). Nest-trees in Cambodia were all of five species—Dipterocarpus intricatus, D. obtusifolius, D. alatus, Hopea odorata and Anisoptera costata—with two of these, D. intricatus and D. obtusifolius, accounting for 40 of the different nests found (6 Keo, O. (2008). Ecology and conservation of the Giant Ibis Thaumatibis gigantea in Cambodia. BirdingASIA. 9: 100–106. Close ). Nests  usually sited in crowns of trees and supported by at least three branches, generally > 4 km from the nearest village and within 1 km of pools and earthworm mounds (6 Keo, O. (2008). Ecology and conservation of the Giant Ibis Thaumatibis gigantea in Cambodia. BirdingASIA. 9: 100–106. Close ); nest itself does not seem to be described. Nests in wet season, commencing late Jun in Cambodia (8 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. Close ). Clutch usually, perhaps always, two eggs, probably laid at 1·5-day intervals, incubated 32 ± 1·16 days, with fledging taking 70 ± 4·64 days (8 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. Close ). Nest predation by common palm civets (Paradoxurus hermaphroditus) and/or yellow-throated martens (Martes flavigula) reported in Cambodia (seven of ten nestlings in five nests were predated in 2004) (8 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. Close ), and has led to the development of a predator-exclusion device (a smooth hard plastic belt fixed to the base of the nest-tree), which seems effective (6 Keo, O. (2008). Ecology and conservation of the Giant Ibis Thaumatibis gigantea in Cambodia. BirdingASIA. 9: 100–106. Close ) and costs just US$5 per nest (8 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. Close ), with the number of young fledged per nest 50% higher for protected nests than unprotected nests (8 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. Close ). Unsuccessful predation attempts on ibis nestlings by Large-billed Crow (Corvus macrorhynchos) and Changeable Hawk-eagle (Nisaetus cirrhatus) have also been observed in Cambodia (8 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. Close ). Family parties remain together for some time, perhaps even as long as next breeding season, with juveniles partially dependent on the adults for quite long periods (7 Eames, J.C. (2011). Feeding ecology of Giant Ibis Thaumatibis gigantea, Stung Treng province, Cambodia. BirdingASIA. 16: 98–100. Close ).

CRITICALLY ENDANGERED. Once widespread in Indochina, this large ibis is extremely sensitive to human disturbance and was not seen between 1964 and 1993. It is even now probably close to extinction, with an extremely small population that continues to suffer a rapid decline BirdLife International (2014) Species factsheet: Thaumatibis gigantea. Downloaded from http://www.birdlife.org on 22/12/2014. . Overall range covers 24,700 km² BirdLife International (2014) Species factsheet: Thaumatibis gigantea. Downloaded from http://www.birdlife.org on 22/12/2014. in N Cambodia and S Laos, with a fairly recent record from Yok Don National Park, Vietnam. Global population estimated at 115 pairs, and about 345 birds in 2012 BirdLife International (2014) Species factsheet: Thaumatibis gigantea. Downloaded from http://www.birdlife.org on 22/12/2014. . Some areas of high density in N Cambodia, including Preah Vihear Protected Forest and Kulen Promtep Wildlife Sanctuary (with 30–40 nests monitored annually) and Western Siem Pang Important Bird Area (possibly 40 pairs), with relatively low-density populations in Lomphat Wildlife Sanctuary, Seima Protection Forest, Mondulkiri Protected Forest and Phnom Prich Wildlife Sanctuary, and additional recent records from Veunsai proposed Protected Forest in Ratanakiri province BirdLife International (2014) Species factsheet: Thaumatibis gigantea. Downloaded from http://www.birdlife.org on 22/12/2014. . Formerly bred in C & SE Thailand, Cambodia, S Laos (though only two records prior to 1993) (5 Thewlis, R.M. and Timmins, R.J. (1996). The rediscovery of Giant Ibis Pseudibis gigantea with a review of previous records. Bird Conservation International. 6(4): 317–324. Close ) and S Vietnam, but seems always to have been uncommon and local throughout range; flocks of up to 40 birds in Cambodia in 1920s. In 1964 recorded on Cambodia–Laos border and thereafter went unrecorded (other than undocumented claim of small numbers at Dong Thap Muoi, an inland delta of the Mekong, Vietnam) until Feb–Mar 1993, when species was rediscovered in Xe Piane National Biodiversity Conservation Area, Laos (9 Anderson, G. (1993). Around the Orient: Laos expedition finds Giant Ibis. Bull. Oriental Bird Club. 17: 12–13. Close ), and was followed by additional records from the same general area in May 1995 and from Tonlé San, NE Cambodia, in Aug 1994, where species had long been speculated to persist (5 Thewlis, R.M. and Timmins, R.J. (1996). The rediscovery of Giant Ibis Pseudibis gigantea with a review of previous records. Bird Conservation International. 6(4): 317–324. Close ) and where local wildlife traders offered up to US$500 for a pair of this ibis (10 Pitches, A. (1997). Around the Orient: Over-harvesting of waterbird eggs curtailed. Bull. Oriental Bird Club. 26: 15. Close ); the species is also traded as food in Cambodia (11 Kohler, M. (2000). Conservation Fund: Survey for Sarus Crane and other threatened bird species in southern Kampong Thom province, Cambodia. Bull. Oriental Bird Club. 31: 15–16. Close ). Subsequently, in May 1996, recorded in Dong Khanthung Proposed Protected Area, Laos (12 Evans, T. D., H. C. Towll, R. J. Timmins, R. M. Thewlis, A. J. Stones, W. G. Robichaud, and J. Barzen (2000). Ornithological records from the lowlands of southern Laos during December 1995–September 1996, including areas on the Thai and Cambodian borders. Forktail 16:29–52. Close ), while a population of c. 45 individuals was found in Preah Vihear province , N Cambodia, in early 2001 (13 Pitches, A. (2001). Around the Orient: Giant Ibises found. Bull. Oriental Bird Club. 34: 47. Close ). Extinct in Thailand, with last confirmed record in 1913 and only five ever documented (5 Thewlis, R.M. and Timmins, R.J. (1996). The rediscovery of Giant Ibis Pseudibis gigantea with a review of previous records. Bird Conservation International. 6(4): 317–324. Close ). Loss of wetlands probably one of main causes of decline: conversion for agriculture of central valley of Chao Phraya thought to have been instrumental in extirpation from Thailand. Large-scale deforestation of lowland dry forest for agro-industry including rubber, cassava, wood pulp and teak plantations, recently recognized as greatest threat. Hunting is also a factor. Human population is increasing within species’ range, mostly through immigration from other provinces in Cambodia, while subsequent expansion of agriculture and increasing hunting pressure (large size makes it very vulnerable) and disturbance at feeding sites is causing loss of breeding habitat; a prolonged drought in the 2009–2010 dry season appeared to lower breeding success by c. 50%; and climate change may pose a long-term threat.