Fr: Marabout argala
Ang: Greater Adjutant
All: Großer Adjutant
Esp: Marabú Argala
Ita: Marabù asiatico maggiore
Nd: Indische Maraboe
Sd: Större adjutantstork
Text by Nicole Bouglouan
Sources:
HANDBOOK OF THE BIRDS OF THE WORLD vol 1 by Josep del Hoyo-Andrew Elliot-Jordi Sargatal - Lynx Edicions - ISBN: 8487334105
A Field Guide to the Birds of South-East Asia by Craig Robson. New Holland Publishers. ISBN: 9781780090498
Animal Diversity Web (University of Michigan Museum of Zoology)
Wikipedia, the free encyclopaedia
THE HINDU - Endangered Greater Adjutant Stork finds secure home to breed
Canisius Ambassadors for Conservation
THE TRIBUNE - Assam village made famous by a bird
Greater Adjutant
Leptoptilos dubius
Ciconiiformes Order – Ciconiidae family
INTRODUCTION:
The Greater Adjutant is a huge, bulky stork of NE India and SE Asia. Like the Lesser Adjutant and the Marabou Stork, it has a huge, thick bill and bare skin on the head. The large wingspan allows the bird to soar easily, but it flies with retracted neck due to the heavy bill.
The name “adjutant” is derived from it stiff gait while walking on the ground.
The Greater Adjutant has very small population that is declining rapidly. This species is threatened by habitat destruction, pollution and persecution. It is currently classified as Endangered.
DESCRIPTION OF THE BIRD:
Biometrics:
Length: 120-152 cm
Wingspan: 250 cm
Weight: 7-11 kg (captive juvenile)
The Greater Adjutant in non-breeding plumage has bluish-grey upperparts contrasting with pale grey greater coverts and tertials. The tail is dark grey.
On the underparts, body and wing-coverts are whitish. The undertail feathers are blackish.
The naked head is pinkish like neck and pronounced drooping neck-pouch. We can see a white ruff around the base of the neck, and some dark hair-like feathering on head and neck.
The large, deep-based bill is dark at base, with pale horn mandible. The culmen is convex. The eyes are bluish-white. Legs and feet are dark grey. However, the legs often appear whitish, due to urohydrosis, in order to cool them with their dejections.
Male and female are similar.
The Greater Adjutant in breeding plumage has blackish face and forehead, whereas head and neck are redder. We can see an inflated hanging gular pouch and a reddish bulge at base of the rear neck. The upperparts are paler bluish-grey with silvery greater coverts and tertials. The neck pouch becomes bright saffron-yellow whereas the upper tibia is reddish.
The juvenile has narrower bill than adults and the eyes are brownish-blue to bluish-brown. Head and neck show denser hair-like feathering. The upperparts are duller. The wings are all-dark first, before to acquire a brown band across greater coverts and tertials.
RANGE:
The Greater Adjutant is found in E Nepal, N India and N Bangladesh and Indochina (mainly in Cambodia). It breeds only in Assam Valley, Bihar and Cambodia.
HABITAT:
The Greater Adjutant frequents freshwater marshes and pools, freshwater swamp forest and sometimes ricefields and open areas. The species occurs in lowlands, but it may occasionally reach 1500 metres of elevation in Nepal, in Himalayan foothills.
At other times, the birds can be seen foraging at urban disposal sites. They often gather around carcasses and at rubbish dumps in open fields but also near towns. It can be seen perched on houses and wandering about by markets for food.
CALLS AND SONGS:
The Greater Adjutant is often silent away from the nest. Like other Ciconiidae, it performs bill-clattering during the displays, but also produces low grunting, croaking and roaring sounds.
BEHAVIOUR IN THE WILD:
The Greater Adjutant feeds mainly at carcasses and often scavenges through garbage disposal areas. The digestive system of these large storks allows them to eat and swallow bones, giving them the name “hargila” (bone swallower).
However, the Greater Adjutant also forages in shallow, drying pools where it searches for insects, frogs, large fish, crustaceans, and sometimes injured ducks or waders.
It forages by using a tactile technique, holding its beak open underwater and waiting for passing prey between the open mandibles.
The Greater Adjutant is monogamous, but the pair bond does not always last for life. It is colonial nester. The males advertise their territories by perching on the nesting branch while performing bill-clattering with the bill upwards. If some females perch close to the males, they present some twigs as courtship, but they also adopt ritualized postures, holding the huge bill close to a potential mate or hiding her head under the chin. Both mates perform other displays together, especially up-down bobbing motions.
The Greater Adjutant usually disperses after breeding and it is locally migratory and subject to wandering movements. It was formerly more widely distributed in India and Bangladesh. It is a non-breeding visitor in Nepal. But current/former status is unclear.
The Greater Adjutant retracts its neck in flight, probably due to the heavy bill. The large wings allow the bird to soar easily.
REPRODUCTION OF THIS SPECIES:
The breeding season takes place between October-December and February in Burma, Cambodia and India.
The Greater Adjutant nests in colonies, but now more restricted to small colonies of less than 30 pairs and scattered solitary pairs. It shares these colonies with other species such as the Lesser Adjutant, the Asian Openbill and some pelicans. The colonies are established in large trees with sparse foliage, in order to make easier both landing and take-off for these large birds.
The stick nest is a large, bulky structure with a deep cup lined with fresh vegetation, placed in tree between 12 and 30 metres above the ground, and sometimes on rock ledges.
The female lays 2-3 white eggs, becoming stained some days later. Both adults incubate during 28-30 days. The chicks are fed by both parents during five months. They can fly in the vicinity of the colony about four months after hatching, but they are still fed by their parents for one month more.
PROTECTION / THREATS / STATUS:
The Greater Adjutant is threatened by habitat loss, both feeding and nesting habitats, through drainage of wetlands, disturbance, pollution and persecution, owing to its pest status. Reduction of open rubbish dumps with carcasses and foodstuffs is a significant threat for these scavengers.
The population has declined catastrophically with a recent estimation of 800/1,200 mature individuals, equating to 1,200/1,800 individuals. This population is rapidly decreasing.
The Greater Adjutant is currently classified as Endangered, in spite of legal protection within the range, and its presence in some protected national parks in Assam, India.
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