The giant ibis (''Thaumatibis gigantea''), the only species in the
monotypic
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''Thaumatibis'', is a wading
bird
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...
of the
ibis
The ibises () (collective plural ibis; classical plurals ibides and ibes) are a group of long-legged wading birds in the family Threskiornithidae, that inhabit wetlands, forests and plains. "Ibis" derives from the Latin and Ancient Greek word f ...
family,
Threskiornithidae
The family Threskiornithidae includes 36 species of large wading birds. The family has been traditionally classified into two subfamilies, the ibises and the spoonbills; however recent genetic studies have cast doubt on this arrangement, and hav ...
. It is confined to northern Cambodia, with a few birds surviving in extreme southern Laos and a recent sighting in
Yok Đôn National Park, Vietnam.
Habitat and range
The giant ibis is a lowland bird that occurs in
marsh
A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found at ...
es,
swamp
A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...
s,
lake
A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...
s, wide
river
A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...
s, flooded
plain
In geography, a plain is a flat expanse of land that generally does not change much in elevation, and is primarily treeless. Plains occur as lowlands along valleys or at the base of mountains, as coastal plains, and as plateaus or uplands ...
s and semi-open
forest
A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...
s as well as pools, ponds and seasonal water-meadows in denser
deciduous forest
In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, aft ...
. It generally is found in lowlands. One bird was collected in a
Malay
Malay may refer to:
Languages
* Malay language or Bahasa Melayu, a major Austronesian language spoken in Indonesia, Malaysia, Brunei and Singapore
** History of the Malay language, the Malay language from the 4th to the 14th century
** Indonesi ...
paddyfield
A paddy field is a flooded field (agriculture), field of arable land used for growing Aquatic plant, semiaquatic crops, most notably rice and taro. It originates from the Neolithic rice-farming cultures of the Yangtze River basin in sout ...
. Formerly the giant ibis was believed to breed in eastern Thailand, central and northern Cambodia, southern Laos and southern Vietnam. It was still fairly common in the
Mekong Delta
The Mekong Delta ( vi, Đồng bằng Sông Cửu Long, lit=Nine Dragon River Delta or simply vi, Đồng Bằng Sông Mê Kông, lit=Mekong River Delta, label=none), also known as the Western Region ( vi, Miền Tây, links=no) or South-weste ...
until the 1920s but is now almost depleted, with a small remnant population breeding in Cambodia, southern Laos and possibly in Vietnam.
Description
True to its name, it is the largest extant ibis species. Adults are long and weigh about .
[ Among standard measurements, the wing chord is , the ]tail
The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, r ...
is , the tarsus is and the culmen is . The adults have overall dark grayish-brown plumage with a naked, greyish 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, shorter bills and brown eyes.[
It has a loud, ringing call, frequently repeated around dawn or dusk, ''a-leurk a-leurk''.][
]
Life history
Very little is known of the giant ibis's life history. It eats aquatic invertebrate
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
s, eel
Eels are ray-finned fish belonging to the order Anguilliformes (), which consists of eight suborders, 19 families, 111 genera, and about 800 species. Eels undergo considerable development from the early larval stage to the eventual adult stage ...
s, crustacean
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...
s and small amphibian
Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terres ...
s and reptile
Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...
s. Insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...
s such as locust
Locusts (derived from the Vulgar Latin ''locusta'', meaning grasshopper) are various species of short-horned grasshoppers in the family Acrididae that have a swarming phase. These insects are usually solitary, but under certain circumstanc ...
s and cicada
The cicadas () are a superfamily, the Cicadoidea, of insects in the order Hemiptera (true bugs). They are in the suborder Auchenorrhyncha, along with smaller jumping bugs such as leafhoppers and froghoppers. The superfamily is divided into two ...
s are eaten regularly when abundant and seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...
s occasionally supplement the diet. Outside of the breeding season, frog
A frog is any member of a diverse and largely Carnivore, carnivorous group of short-bodied, tailless amphibians composing the order (biology), order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-f ...
s and mole-crickets appear to be perhaps the most significant prey types for giant ibises. They mainly forage in muddy substrate in shallow waters, though can feed at all depths in seasonal forest pools. Feeding flocks may consist of a breeding pair or small family group and have been observed mixing with black ibis
The red-naped ibis (''Pseudibis papillosa'') also known as the Indian black ibis or black ibis is a species of ibis found in the plains of the Indian Subcontinent. Unlike other ibises in the region it is not very dependent on water and is often f ...
es. Next to nothing is known of its breeding behaviour, but it nests in tree
In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
s, with a possible preference for ''Dipterocarpus
'' D. retusus'' in Köhler
''Dipterocarpus'' is a genus of flowering plants and the type genus of family Dipterocarpaceae.
''Dipterocarpus'' is the third-largest and most diverse genus among the Dipterocarpaceae. The species are well known for ...
'' trees.[ Usually, nests are located at least from human habitations, although the species is not especially shy around or fearful of humans unless persistently harassed or hunted.][ Females lay two eggs at the start of the rainy season, around June to September. ]Earthworm
An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. Th ...
s taken from their mounds in wet grasslands appears to be an important food source for nesting ibises of this species. In general, the species is residential but can wander widely for food or in response to disturbances. The giant ibis is generally territorial and may remain with a family group throughout the year. However, in the dry season, when they are not nesting, groups of up to seven individuals, sometimes likely unrelated, have been observed feeding together.
Status
The giant ibis is considered to be Critically Endangered on the IUCN Red List
The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...
. The primary causes seem to be drainage of wetlands for cultivation and the epidemic clear-cutting of forest for rubber, cassava, wood pulp and teak plantations in south-east Asia. Habitats may also face ravaging due to local human warfare. Increasing human populations in Cambodia have in turn lead to disturbance and further lowland deforestation
Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated d ...
. The ibis may be hunted for meat by people and eggs may be predated by the Asian palm civet
The Asian palm civet (''Paradoxurus hermaphroditus''), also called common palm civet, toddy cat and musang, is a viverrid native to South and Southeast Asia. Since 2008, it is IUCN Red Listed as Least Concern as it accommodates to a broad range ...
and the yellow-throated marten
The yellow-throated marten (''Martes flavigula'') is a marten species native to Asia. It is listed as Least Concern on the IUCN Red List due to its wide distribution, evidently relatively stable population, occurrence in a number of protected are ...
, with the species certainly unable to withstand sustained predation. A reduction in seasonal pools in forest, previously made by now depleted populations of megafauna
In terrestrial zoology, the megafauna (from Greek μέγας ''megas'' "large" and New Latin ''fauna'' "animal life") comprises the large or giant animals of an area, habitat, or geological period, extinct and/or extant. The most common threshold ...
(especially wild Asian water buffalo
The wild water buffalo (''Bubalus arnee''), also called Asian buffalo, Asiatic buffalo and wild buffalo, is a large bovine native to the Indian subcontinent and Southeast Asia. It has been listed as ''Endangered'' in the IUCN Red List since 198 ...
), may also negatively effect them. Local droughts, possibly related to global climate change
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
, have appeared to have further compromised the breeding habitat and behaviour of the species. Some conservation efforts have been undertaken, including protecting nests by the installation of metal belts that prevent predators from accessing them, but the protection of ideal habitat and the increasing human populations in Cambodia continues to be a vexing challenge. Increasing ecotourism
Ecotourism is a form of tourism involving responsible travel (using sustainable transport) to natural areas, conserving the environment, and improving the well-being of the local people. Its purpose may be to educate the traveler, to provide funds ...
in the region and education to local people is clearly required for the species to successfully recover from the brink of extinction.[ The current population is estimated at 100 pairs, with a total population (including young and juveniles) of fewer than 500 individuals. However, even these figures may be optimistic.] In 2018 the IUCN
The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
stated there were less than 200 mature individuals in the population.
References
*Hancock & Kushan, ''Storks, Ibises and Spoonbills of the World''. Princeton University Press (1992), .
External links
BirdLife species factsheet.
ARKive pics and videos
{{Taxonbar, from=Q931759
Threskiornithidae
Birds of Southeast Asia
Birds of Laos
Birds of Cambodia
Birds of Vietnam
Birds described in 1877
Taxa named by Émile Oustalet
National symbols of Cambodia