The lesser adjutant (Leptoptilos javanicus) is a large wading bird in the stork family Ciconiidae. Like other members of its genus, it has a bare neck and head. It is however more closely associated with wetland habitats where it is solitary and is less likely to scavenge than the related greater adjutant. It is a widespread species found from India through Southeast Asia to Java.
A large stork with an upright stance, a bare head and neck without a pendant pouch, it has a length of 87–93 cm (34–37 in) (outstretched from bill-to-tail measurement), weighs from 4 to 5.71 kg (8.8 to 12.6 lb) and stands about 110–120 cm (43–47 in) tall. The only confusable species is the greater adjutant, but this species is generally smaller and has a straight upper bill edge (culmen), measuring 25.8–30.8 cm (10.2–12.1 in) in length, with a paler base and appears slightly trimmer and less hunch-backed. The skullcap is paler and the upper plumage is uniformly dark, appearing almost all black. The nearly naked head and neck have a few scattered hair-like feathers. The upper shank or tibia is grey rather than pink, the tarsus measures 22.5–26.8 cm (8.9–10.6 in). The belly and undertail are white. Juveniles are a duller version of the adult but have more feathers on the nape. During the breeding season, the face is reddish and the neck is orange. The larger median wing coverts are tipped with copper spots and the inner secondary coverts and tertials have narrow white edging. The wing chord measures 57.5–66 cm (22.6–26.0 in) in length. Like others in the genus, they retract their necks in flight. In flight, the folded neck can appear like the pouch of the greater adjutant. Males and females appear similar in plumage but males tend to be larger and heavier billed.
Distribution and habitat
The lesser adjutant is often found in large rivers and lakes inside well wooded regions, in freshwater wetlands in agricultural areas, and coastal wetlands including mudflats and mangroves. It is found in India, Nepal, Sri Lanka, Bangladesh (A colony with about 6 nests and 20 individuals was discovered near Thakurgaon in 2011.), Myanmar, Thailand, Vietnam, Malaysia, Laos, Singapore, Indonesia and Cambodia. The largest population is in Cambodia. In India they are mainly distributed in the eastern states of Assam, West Bengal and Bihar. It may occur as a vagrant on the southern edge of Bhutan. They are extremely rare in southern India. In Sri Lanka, they are found in lowland areas largely within protected areas, though they also use forested wetlands and crop fields.
Behaviour and ecology
The lesser adjutant stalks around wetlands feeding mainly on fish, frogs, reptiles, large invertebrates, rodents, small mammals and rarely carrion. Location of prey appears to be entirely visual, with one observation of storks sitting on telegraphic poles apparently scanning a marsh for prey.
They are largely silent but have been noted to clatter their bill, hiss and moan at the nest. During one of the threat displays called the "Arching display" that is given in the presence of intruders, adults extend their neck and sometimes give a hoarse wail.
Courtship behaviour of the lesser adjutant is identical to other species of the Leptoptilos genus. During pair formation, female birds lift their heads in a scooping motion with bill-clattering (called the "Balancing Posture"). They are solitary except during the breeding season when they form loose colonies, never exceeding 20 nests in a single colony. The breeding season is February to May in southern India and November to January in north-eastern India, beginning as early as July. The nest is a large platform of sticks placed on a tall tree. The nest diameter is more than a metre and up to a metre deep. The clutch consists of two to four white eggs that are rapidly soiled during incubation. Incubation period is 28-30 days. In eastern Nepal, four colonies consisting of 61 nests were all built on the tree species Adina cordifolia and Bombax ceiba. Other tree species on which nests have been found in India and Myanmar include Alstonia scholaris and Salmalia malabarica with some nests located as high as 46 m. Nests have not yet been located in Sri Lanka, though young birds have been observed feeding in crop fields and in freshwater wetlands.
A lesser adjutant paired and hybridized with a painted stork at Dehiwala Zoo, Sri Lanka and at Kuala Lumpur Zoo. The hybrid young had plumage and bill-size of the adjutant, but stance and bill shape of the painted stork.
Captive in Vietnam (the bird in the water is a painted stork)
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