[order] CICONIIFORMES | [family] Ciconiidae | [latin] Leptoptilos dubius | [authority] Gmelin, 1789 | [UK] Greater Adjutant | [FR] Marabout argala | [DE] Grosser Adjutant | [ES] Marabu Argala | [NL] Indische Maraboe
Leptoptilos is a genus of very large tropical storks. Two species are resident breeders in southern Asia, and the Marabou Stork is found in sub-Saharan Africa. These are huge birds, typically 110?150 cm tall with a 210?250 cm wingspan. The three species each have a black upper body and wings, and white belly and undertail. The head and neck are bare like those of a vulture. The huge bill is long and thick. Juveniles are a duller, browner version of the adult. Leptoptilos storks are gregarious colonial breeders in wetlands, building large stick nests in trees. They feed on frogs, insects, young birds, lizards and rodents. They are frequent scavengers, and the naked head and neck are adaptations to this, as are those of the vultures with which they often feed. A feathered head would become rapidly clotted with blood and other substances when a scavenging bird’s head was inside a large corpse, and the bare head is easier to keep clean. Most storks fly with neck outstretched, but the three Leptoptilos storks retract their necks in flight like a heron. There is an ample fossil record of this genus. L. titan, which was hunted by prehistoric humans, was truly gigantic, and L. falconeri possibly was one of the most widespread storks worldwide during the Pliocene.
Huge, dark stork with very thick bill and pendulous neck-pouch. Pinkish naked head, white neck-ruff. Pale grey greater coverts and tertials contrasting with otherwise dark upperwing. Underwing-coverts paler than flight feathers. Juvenile has narrower bill than adult, denser head and neck-down and, initially, all dark wings. Similar spp. Lesser Adjutant L. javanicus is smaller, lacks neck pouch, has black greater coverts and tertials
Oriental Region : North India
While breeding in the dry season (October-May/June) it inhabits wetlands, nesting in tall trees, bamboo plantations and historically on cliffs. Breeding is thought to coincide with the dry season in order to take advantage of abundant prey as water levels recede. In north-east India, it occurs close to urban areas, feeding around wetlands in the breeding season, and dispersing to scavenge at rubbish dumps, abattoirs and burial grounds at other times. In Cambodia, it breeds in freshwater flooded forest and areas of dry forest with ephemeral pools, otherwise dispersing to seasonally inundated forest, carcass dumps, tall wet grassland, mangroves and intertidal flats
The species breeds in the dry season; birds congregate at the nesting areas from October onwards and lay eggs between November and January. The species breeds singly, semi-colonially or colonially in traditional arboreal sites which are sometimes used for many years, often in colonies mixed with other waterbirds, including Lesser Adjutant. Characteristically, adjutants of both species tend to place their nest on very tall trees. Of 278 clutches examined in Assam, all contained 2-3 white eggs. Similarly, at the Sittang valley colony most clutches contained three eggs, while those at the Needong Hills comprised 3-4 eggs. The incubation period is 28-30 days. In Assam, 61.3% of eggs in 278 clutches produced fledglings. Both sexes share nest building, incubation and feeding of the nestlings.Adults wil bring water to juveniles on the nest, either to cool them down or for them to drink.
The greater adjutant feeds by sweeping its bill under the surface of the water, or by probing into the substrate. It will consume carrion, fish, frogs, reptiles, crustaceans, large insects and even injured ducks. It is also known to feed in human refuse dumps, where it will take food from other scavengers, including vultures
copyright: Martin Kennewell
This wide-ranging and long-lived species has a very small population which is declining very rapidly. For these reasons it is classified as Endangered. Recent breeding failures in Assam (the species’s stronghold) provide cause for concern and need to be closely monitored.
Leptoptilos dubius was previously widespread and common across much of South and continental South-East Asia but declined dramatically during the first half of the 20th century. It is known to breed only in Assam, India (at least 650-800 birds, or more), and at the Tonle Sap lake (c. 75 pairs) and in Kulen Promtep Wildlife Sanctuary in the Northern Plains (c. 15-20 pairs), Cambodia. Recent records from Nepal, Bangladesh, and Thailand are presumed to refer to wanderers from India and Cambodia. Huge numbers once bred in Myanmar but there have been just two recent reports from Meinmahla Kyun in 1998 and Kachin State in 2006. There are no confirmed records from Laos in recent years. Breeding success in recent seasons has been extremely poor in Assam: the number of nests in colonies is declining sharply, but for unknown reasons. Available data suggests that Cambodian populations declined heavily in the decades up to and including the 1990s. By 2001, several breeding sites recorded in the 1990s had been abandoned. Since 2001 protection measures at two known breeding sites (Prek Toal on the Tonle Sap and Kulen Promtep in Preah Vihear) have led to a stabilisation of national population declines and possible minor recoveries
The greater adjutant was formerly found in South and Southeast Asia, but there are now just two small and separate breeding populations; one in Assam, India and one in Cambodia. A migratory bird, the greater adjutant also visits Viet Nam, Thailand and Burma when not breeding