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.
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|size min.:||122||cm||size max.:||129||cm|
|incubation min.:||28||days||incubation max.:||30||days|
|fledging min.:||47||days||fledging max.:||52||days|
populations dwindle. The timing of breeding events varies geographically and fluctuates annually, but tends to coincide with the beginning of the dry season.
Colonies tend to be sited in clumps of tall trees with a thick undergrowth of bamboo, but the key factor appears to be the proximity of water: colonies are generally
surrounded by wetlands (6-100 cm deep), marshy land (2-50 cm deep), small or large waterholes (20-150 cm deep) and paddyfields (1-50 cm deep). In Assam, a full clutch contains 2-4 eggs. Nests in Myanmar usually contained 3-4 eggs. In Indonesia clutches of one egg are apparently common; however, in 1998 the number of young in nests was usually two and in one case three. The incubation period generally lasts 28-30 days, during which time parental duties are shared almost equally by both adults. After hatching, at which time the nestlings are weak and sparsely covered by thin grey down, the adults brood almost constantly for 12-14 days, the amount of time decreasing gradually after the first week, except if there is any rain before the fourteenth day after hatching, in which case brooding recommence. Both adults bring food to the nestlings.
Video Lesser Adjutant
copyright: Stefan Behrens
Leptoptilos javanicus has an extensive range across South and South-East Asia. Substantial populations remain only in India (mostly in Assam, with c.2000 birds, West Bengal and Bihar where 42 nests confirmed breeding in 2004), Indonesia (c.2000 in 1993, the majority on Sumatra) and Cambodia (1000 individuals or >300 pairs). Smaller breeding populations (<200 pairs) occur in Nepal (in 2003 c.50 birds were recorded in Royal Chitwan National Park: the national population was recently estimated at c.300 individuals following surveys in east, central and western Nepal), Sri Lanka, Bangladesh, Myanmar, Laos, Malaysia (c.500 individuals), Brunei, Vietnam and Thailand. It has been recorded in Bhutan but is thought to be extinct in China and in Singapore. Formerly common and widespread, it has declined dramatically across its range and has been extirpated from many areas in recent decades owing to persistent un-regulated harvesting of eggs and chicks at nesting colonies. However, some populations at least seem to be relatively stable, e.g. numbers in the Matang Mangrove Forest, Malaysia have remained relatively constant for 20 years. The current population estimate is 5000 birds, however, an increase in survey effort across much of the region has revised many national totals upwards. A recent analysis of Cambodian records estimated a national population of c.1870 pairs; precautionary interpretation of this figure suggests the previous national estimate of 1000 individuals should be revised upwards considerably to 2500-4000 individuals. Therefore, overall the global population may be considerably larger than previous estimates. Several threats are contributing to its decline, with their relative importance varying across its range. The loss of nest-sites through the felling of colony nest trees is a major threat, particularly in Assam. In many areas, drainage and conversion of wetland feeding areas, agricultural intensification, increased pesticide use and disturbance, and hunting and collection of eggs, chicks and adults are major threats. Coastal populations are threatened by large-scale development, including aquaculture and the clearance of mangroves. A recent, and very serious threat, recorded in Nepal and Cambodia is the practice of poisoning pools to catch fish, which leads to incidental mortality of this species.