Overview

Brief Summary

Biology

Gathering in compact colonies at the start of the dry season in October, the greater adjutant nests on large, widely branched trees with few leaves (4). It constructs a large platform of sticks with an outer layer of bamboo stems and lines this with leaves. Two to four eggs are laid between November and January. After 28 to 30 days, the eggs hatch, and the nestlings are cared for until April. At the start of the wet season, the greater adjutants migrate to northern India (3). 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 (3).
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Description

This huge stork has a naked pink head, a very thick yellow bill and a low-hanging neck pouch. The neck ruff is white and, other than the pale grey leading edge of each wing, the rest of the greater adjutant's body is dark grey. Juveniles have a narrower bill, thicker down on the head and neck and entirely dark wings (2).
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Distribution

Range Description

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 (Birdlife International 2001). It is known to breed in Assam, India (at least 650-800 birds, or more [Choudhury 2000]), and at the Tonle Sap lake (c.75 pairs) and in Kulen Promtep Wildlife Sanctuary in the Northern Plains (c.15-20 pairs), Cambodia (T. Clements in litt. 2007). The species was reported to be breeding in Bihar, India, in 2004, and a small breeding population was discovered in the state on the Ganga and Kosi river floodplains in 2006 (Mishra and Mandal 2009). The population there appears to be increasing, with at least 156 estimated in 2008 and over 300 individuals in 2011, up from 78 in 2007 (Mishra and Mandal 2009, Kahn 2011). 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 (G Chunkino in litt. 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 (Goswami and Patar 2006). Despite this, large flocks of a few hundred birds are still noted around the city of Guwahati, which may provide feeding areas for around half of the species's world population (Choudhury 2008). Available data suggest 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 (Clements et al. 2007a, b).

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Range

NE India (population ±300 birds 1992).

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Geographic Range

Greater adjutants (Leptoptilos dubius) are exceedingly rare in their range from Northern India to Indochina and may breed exclusively in the Brahmaputra Valley of Assam. In the early part of the 20th century, large breeding populations of greater adjutants were common throughout Northern India, Bangladesh, Nepal and Southern Vietnam.

Biogeographic Regions: oriental (Native )

  • Elliot, A., J. Del-Hoyo, D. Christie. 1992. Handbook of the Birds of the World. Vol 1: Ostrich to Ducks. Barcelona, Spain: Lynx Edicions.
  • Singha, H., A. Rahmani, M. Coulter, S. Javed. 2002. Nesting Ecology of the Greater Adjutant Stork in Assam, India. Waterbirds, 25(2): 214-220.
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Range

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 (3).
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Physical Description

Morphology

Physical Description

Greater adjutants are large birds, ranging in height from 120 to 152 cm with an impressive 250 cm wingspan. A long, thick yellow bill precedes the sparsely feathered, yellow to pink head and neck. The head is typically dappled with dark scabs of dried blood and characterized by the presence of a pendulous, inflatable gular pouch. The legs are naturally dark in color but frequently appear ashen due to regular defecation on the legs. When in flight, greater adjutants are recognizable by their white underside feathers and tendency to retract their necks like a heron. A mixture of white and gray feathers, which appear darker during the non-breeding season, adorn the rest of the body. Juvenile greater adjutants resemble adults, but have duller plumage and more feathers around the neck. The mass of these birds is unknown in the wild, but is estimated to be the heaviest of the storks.

Range length: 120 to 152 cm.

Average wingspan: 250 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: sexes alike; ornamentation

  • Rahmani, A., G. Narayan, L. Rosalin. 1990. Status of the Greater Adjutant (Leptoptilos dubius) in the Indian Subcontinent. Colonial Waterbirds, 13(2): 139-142.
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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
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 (Singha et al. 2003). 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.


Systems
  • Terrestrial
  • Freshwater
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Greater adjutants (Leptoptilos dubius) have been observed in a variety habitats including marshes, lakes and jheels (shallow expansive lakes) as well as dry grasslands and fields. These birds are most frequently associated with slaughter houses and refuse sites near human settlements and were formerly common on the streets and rooftops of Calcutta. They typically nest in large trees and rock pinnacles near human settlements.

Habitat Regions: tropical ; terrestrial

Terrestrial Biomes: savanna or grassland ; forest

Aquatic Biomes: lakes and ponds; temporary pools

Wetlands: marsh

Other Habitat Features: urban ; suburban ; riparian

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Inhabits wetland habitats, especially those that are partially dry and where fish are abundant, including lakes, swamps, river beds, stagnant pools and paddy fields (3).
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Trophic Strategy

Food Habits

In their native range, where they are primarily scavengers of large carrion, greater adjutants are known by the name "hargila," meaning bone swallower. They were once prevalent in Calcutta, where their tendency to consume human corpses left to rot in the streets was valued. One record indicates that a single greater adjutant effortlessly swallowed two buffalo vertebrae, measuring approximately 30 cm in length, in less than five minutes.  Greater adjutants are most commonly found scavenging in mixed flocks near human garbage dumps or large carcasses. They can also be seen foraging independently near drying pools where they hunt insects, frogs, large fish, crustaceans and injured waterfowl. When foraging, greater adjutants use a method of tactile foraging where they hold their beaks open underwater and patiently wait for a prey item to swim between the open mandibles.

Animal Foods: birds; mammals; amphibians; fish; carrion ; insects; aquatic crustaceans

Primary Diet: carnivore (Scavenger )

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Associations

Ecosystem Roles

Greater adjutants are important scavengers of large carrion and likely contribute to sanitation and disease control in the environment. Like many birds, greater adjutants are hosts to avian lice including Colpocephalum cooki and Ciconiphilus temporalis.

Ecosystem Impact: biodegradation

Commensal/Parasitic Species:

  • Price, R., J. Beer. 1965. A Review of Ciconiphilus Bedford (Mallophaga: Menoponidae). The Canadian Entomologist, 97/6: 657-666.
  • Price, R., J. Beer. 1965. The Colpocephalum (Mallophaga: Menoponidae) of the Ciconiiformes. Annals of the Entomological Society of America, 58/1: 111-131.
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Predation

No natural predators have been reported for this species. Unhealthy or young birds are likely preyed upon by local carnivores.

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Life History and Behavior

Behavior

Communication and Perception

Greater adjutants lack vocal muscles so they rely on unique behaviors and tactile forms of communication to interact with each other. Males often utilize beak clattering to advertise their territory and ward off other males. Males attract mates by presenting them with fresh twigs and later holding their beaks close to the female. Breeding pairs also perform head bobbing rituals that likely reinforce their pair-bond. Like all birds, greater adjutants perceive their environments through visual, auditory, tactile, and chemical stimuli.

Communication Channels: visual ; tactile ; acoustic

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Life Expectancy

Lifespan/Longevity

Although the longest lifespan of a captive greater adjutant was 43 years, the longevity of these birds in the wild remains unknown.

Range lifespan

Status: captivity:
43 (high) years.

  • Brouwer, K., M. Jones, C. King, H. Schifter. 1992. Longevity and breeding records of storks Ciconiidae in captivity. International Zoo Yearbook, 31/1: 131 - 139.
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Lifespan, longevity, and ageing

Maximum longevity: 43 years (captivity) Observations: One specimen lived 43 years in captivity (Brouwer et al. 1992).
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Reproduction

Other storks are known to be monogamous, but not always paired for life. It is thought that greater adjutants follow this mating system. Great adjutants are colonial nesters and will build many nests in the canopy of a single tree. Males claim suitable nesting branches and advertise their territory by perching on the branch with bills upward and exhibiting bill-clattering. When females perch nearby, males will present them with twigs as part of courtship. Courtship rituals consist more of courtship postures, where males will hold their beaks close to potential mates or tuck the females heads under their chins. Pairs also perform up-down bobbing motions together.

Greater adjutants nest in large, broad-limbed trees with sparse foliage. This choice of nesting tree is thought to facilitate landing and take-off for the large adult birds. Nests are constructed out of sticks and several pairs will often occupy the same tree. While females lay 3 eggs per season, an average of 2.2 chicks per pair are fledged successfully each year. Both parents participate in incubating eggs until they hatch after 28 to 30 days. Chicks fledge at 5 months of age.

Breeding interval: Greater adjutants breed once a year.

Breeding season: Greater adjtants breed during the dry season from October to June.

Average eggs per season: 3.

Range time to hatching: 28 to 30 days.

Average fledging age: 5 months.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)

Both male and female greater adjutants participate in nest building. After the eggs are laid, both parents also incubate the clutch for 28 to 30. The altricial chicks are cared for by both parents until they fledge at 5 months old.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Male, Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)

  • International Union for Conservation of Nature and Natural Resources. 2009. "The IUCN Red List of Threatend Species" (On-line). Accessed February 05, 2010 at http://www.iucnredlist.org/apps/redlist/details/144792/0.
  • Elliot, A., J. Del-Hoyo, D. Christie. 1992. Handbook of the Birds of the World. Vol 1: Ostrich to Ducks. Barcelona, Spain: Lynx Edicions.
  • Singha, H., A. Rahmani, M. Coulter, S. Javed. 2003. Surveys for Greater Adjutant Leptoptilos dubius in the Brahmaputra valley, Assam, India during 1994–1996. Forktail, 19: 146- 148.
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
EN
Endangered

Red List Criteria
A2bcd+3bcd+4bcd;C2a(ii)

Version
3.1

Year Assessed
2013

Assessor/s
BirdLife International

Reviewer/s
Butchart, S.

Contributor/s
Choudhury, A., Chunkino, G., Clements, T., Htin Hla, T., Li, Z. & Rahmani, A.

Justification
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.


History
  • 2012
    Endangered
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Current Listing Status Summary

Status: Endangered
Date Listed: 09/12/2011
Lead Region: Foreign (Region 10) 
Where Listed: Entire


For most current information and documents related to the conservation status and management of Leptoptilos dubius, see its USFWS Species Profile

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Many consider greater adjutants to be the most endangered stork in the world. Captive breeding programs have failed thus far, but efforts to protect natural habitats are active. Unfortunately, their tendency to nest near human settlements may prove fatal.

In the early part of the 20th century, the population size of greater adjutants is said to have numbered in the millions. They were common in Northern India, Bangladesh, Nepal and Southern Vietnam. Beginning in the mid 1980's the population began to decline heavily. Today an estimated 1,000 birds remain and likely breed only in the politically unstable Assam state of northern India. Populations are still declining and the IUCN red list lists greater adjutants as endangered.

Felling of large nesting trees, pollution of freshwater systems and a decline in the disposal of human corpses in public trash dumps are all thought to contribute to the rapid loss of this species. In Assam, recent reports of disease in this species also seems to be a contributing factor in its decline. Results of a survey of Assam residents revealed that only 30% of those polled knew greater adjutants are endangered. Greater community awareness of this unique species may help in its recovery.

CITES: no special status

IUCN Red List of Threatened Species: endangered

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Status

The greater adjutant is classified as Endangered (EN) on the IUCN Red List 2007 (1) and is listed under Schedule IV of the Wildlife Act 1972 (3).
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Population

Population
The total population is estimated to number 800-1,200 mature individuals, roughly equivalent to 1,200-1,800 individuals in total. This is based on estimates of 650-800 birds in Assam, India, plus 150-200 birds in Cambodia, as well as at least 156 birds in Bihar state, India, which may have dispersed from the Assam population.

Population Trend
Decreasing
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Threats

Major Threats
The key threats are direct exploitation, particularly at nesting colonies, habitat destruction, including some felling of nest-trees, and drainage, conversion, pollution and over-exploitation of wetlands. Additionally, the Indian population is threatened by reduced use of open rubbish dumps for the disposal of carcasses and foodstuffs. It has been suggested that recent nesting failures in Assam may be due to disease (Goswami and Patar 2006), which may have a negative impact upon the species in the future. Young birds may also become entangled in fishing nets and the species may suffer from the disturbance of arboreal animals, competition for nesting habitat from the Lesser Adjutant L. javanicus and the exacerbation of persecution levels owing to its pest status (Mishra and Mandal 2009). Poisoning of small wetlands to catch fish in the dry forests of northern and eastern Cambodia potentially poses a significant threat, and in Guwahati, India, pesticide use at open rubbish dumps where storks flocked to feed led to several mortalities in 2005.

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Loss of nesting habitat and feeding sites has had a huge impact on this stork species. Suitable wetland habitats have been cleared, drained, polluted with pesticides and disturbed by humans. Adult birds are hunted and chicks and eggs are collected for trade (3).
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Management

Conservation Actions

Conservation Actions
Conservation Actions Underway
In Assam, it occurs in Kaziranga, Manas and Dibru-Saikhowa National Parks. Since 1991, there have been conservation awareness programmes in Assam. In Nagaon district, Assam, Green Guards (a local NGO) had a project to protect nesting trees and rehabilitate chicks fallen from nests but this has now stopped (A. Choudhury in litt. 2012). In Cambodia, the breeding colony at Prek Toal is a core area of the Tonle Sap Biosphere Reserve. Greater Adjutants historically bred at other sites on the Tonle Sap, but these colonies were abandoned by 2001. Conservation actions to reduce chick and egg collection and other forms of disturbance to the breeding colony at Prek Toal have been in place since the late 1990s, with permanent teams of protectors employed since 2001. The small population in the Northern Plains is largely protected within Kulen Promtep Wildlife Sanctuary. Since 2001, c.95% of waterbird egg and chick collection has been prevented at Prek Toal. It is included in waterbird conservation awareness material in Laos and Cambodia.

Conservation Actions Proposed
Conduct further surveys in Cambodia, Myanmar and Bangladesh. Investigate seasonal movements and threats. Protect nesting and feeding-sites outside protected areas, and plant trees in suitable areas; the nest payment system in Cambodia may be a suitable model. Rewarding the owners of nesting trees may be a means to encourage pride in the conservation of the species (A.R. Rahmani in litt. 2012). Promote strict control of pesticide use around feeding areas. Continue and strengthen on-going conservation actions at the Prek Toal colony, Tonle Sap lake. Establish a wildlife protection office at Tonle Sap lake. Draft and enforce waterbird conservation legislation at Tonle Sap lake. Expand conservation awareness programmes and develop a structured captive breeding programme to support future reintroductions and population supplementation. Initiate a relief programme and promote alternative livelihoods to communities dependent on harvesting large waterbird colonies in Cambodia. Widely implement a policy of rescuing, rehabilitating and releasing chicks that fall from nests for natural reasons, such as during thunder storms (Singha and Rahmani 2006, Singha et al. 2006), and consider placing nets under nest-trees and conducting regular checks at colonies (Singha et al. 2006).

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Conservation

Whilst legally protected in India, Bangladesh, Burma, Thailand, Cambodia and Laos, and occurring in three National Parks in Assam, India, the greater adjutant still suffers from hunting and egg collection due to poor enforcement of protection. There has been some successful control of egg and chick collection following efforts by the Wildlife Protection Office Staff in Cambodia, which resulted in higher numbers of storks the following year. It has been proposed that the greater adjutant should be moved from Schedule IV to Schedule I of the Indian Wildlife Act of 1972 to give it greater priority. Effective land management is necessary for the survival of this species, particularly the control of pesticide use around feeding areas and the protection of feeding areas and nesting sites found outside protected areas. Further research into the seasonal movements of these birds and the threats that face them is also important (3).
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Relevance to Humans and Ecosystems

Benefits

Economic Importance for Humans: Negative

While greater adjutants pose no threat to humans they are often looked upon with disgust because of their general appearance, habit of defecating on their own legs, as well as diet of carrion.

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Economic Importance for Humans: Positive

Greater adjutants are valuable scavengers of discarded human waste, including unburied corpses as well as other large carrion. This service may have a role in preventing the spread of disease.

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Wikipedia

Greater Adjutant

The greater adjutant (Leptoptilos dubius) is a member of the stork family, Ciconiidae. Its genus includes the lesser adjutant of Asia and the marabou stork of Africa. Once found widely across southern Asia, mainly in India but extending east to Borneo, the greater adjutant is now restricted to a much smaller range with only two small breeding populations; one in India with the largest colony in Assam and the other in Cambodia. Populations disperse after the breeding season. This large stork has a massive wedge-shaped bill, a bare head and a distinctive neck pouch. During the day, they soar in thermals along with vultures with whom they share the habit of scavenging. They feed mainly on carrion and offal; however, they are opportunistic and will sometimes prey on vertebrates. The English name is derived from their stiff "military" gait when walking on the ground. Large numbers once lived in Asia, but have declined greatly, possibly due to improved sanitation, to the point of being endangered. The total population in 2008 was estimated at around a thousand individuals. In the 19th century, they were especially common in the city of Calcutta, where they were referred to as the "Calcutta adjutant". Known locally as hargila (derived from the Sanskrit word for "bone-swallower") and considered to be unclean birds, they were largely left undisturbed but sometimes hunted for the use of their meat in folk medicine. Valued as scavengers, they were once used in the logo of the Calcutta Municipal Corporation.

Description[edit]

The greater adjutant is a huge bird, standing tall at 145–150 cm (57–60 in). The average length is 136 cm (54 in) and average wingspan is 250 cm (99 in). While no weights have been published for wild birds, the greater adjutant is among the largest of living storks, with published measurements overlapping with those of the jabiru (Jabiru mycteria), saddle-billed stork (Ephippiorhynchus senegalensis) and marabou stork (Leptoptilos crumeniferus). Juvenile greater adjutant storks in captivity weighed from 8 to 11 kg (18 to 24 lb).[4] For comparison, the heaviest known wild stork was a marabou stork scaling 8.9 kg (20 lb).[5] The huge bill, which averages 32.2 cm (12.7 in) long, is wedge-like and is pale grey with a darker base. The wing chord averages 80.5 cm (31.7 in), the tail 31.8 cm (12.5 in) and the tarsus 32.4 cm (12.8 in) in length. With the exception of the tarsus length, the standard measurements of the greater adjutant are on average greater than that of other stork species.[6] A white collar ruff at the base of its bare yellow to red-skinned neck gives it a vulture-like appearance. In the breeding season, the pouch and neck become bright orange and the upper thighs of the grey legs turn reddish. Adults have a dark wing that contrasts with light grey secondary coverts. The underside of the body is whitish and the sexes are indistinguishable in the field. Juveniles are a duller version of the adult. The pendant inflatable pouch connects to the air passages and is not connected to the digestive tract. The exact function is unknown, but it is not involved in food storage as was sometimes believed. This was established in 1825 by Dr John Adam, a student of Professor Robert Jameson, who dissected a specimen and found the two layered pouch filled mainly with air.[7] The only possible confusable species in the region is the smaller lesser adjutant (Leptoptilos javanicus), which lacks a pouch, prefers wetland habitats, has a lighter grey skull cap, a straighter edge to the upper mandible and lacks the contrast between the grey secondary coverts and the dark wings.[8][9][10]

Like others storks, it lacks vocal muscles and produces sound mainly by bill-clattering, although low grunting, mooing or roaring sounds are made especially when nesting.[2][10][11] The bill-clattering display is made with the bill raised high and differs from that of the closely related African marabou which holds the bill pointed downwards.[8][12]

Taxonomy and systematics[edit]

"Gigantic Crane" from Latham's General Synopsis of Birds (1781–1801)

John Latham wrote about the bird found in Calcutta based on descriptions in Ives's Voyage to India published in 1773 and included an illustration in the first supplement to his General Synopsis of Birds. The illustration was based on a drawing in Lady Impey's collection and Latham called it the gigantic crane and included observations by an African traveller named Smeathman who described a similar bird from western Africa. Johann Friedrich Gmelin used Latham's description and described the Indian bird as Ardea dubia in 1789 while Latham later used the name Ardea argala for the Indian bird. Temminck used the name Ciconia marabou in 1824 based on the local name used in Senegal for the African bird and this was also applied to the Indian species. This led to considerable confusion between the African and Indian species.[13][14] The marabou stork of Africa looks somewhat similar but their disjunct distribution ranges, differences in bill structure, plumage, and display behaviour support their treatment as separate species.[15]

Most storks fly with their neck outstretched, but the three Leptoptilos species retract their neck in flight as herons do, possibly due to the heavy bill.[10] When walking on the ground, it has a stiff marching gait from which the name "adjutant" is derived.[8]

Distribution[edit]

This species was once a widespread winter visitor in the riverine plains of northern India, however their breeding areas were largely unknown for a long time until a very large nesting colony was finally discovered in 1877 at Shwaygheen on the Sittaung River, Pegu, Burma and it was believed that the Indian birds bred there.[16][17] This breeding colony, which also included spot-billed pelicans (Pelecanus philippensis), declined in size and entirely vanished by the 1930s.[18] Subsequently, a nest site in Kaziranga was the only known breeding area until new sites were discovered in Assam, the Tonle Sap lake and in the Kulen Promtep Wildlife Sanctuary. In 1989, the breeding population in Assam was estimated at about 115 birds[18][19][20][21] and between 1994 and 1996 the population in the Brahmaputra valley was considered to be about 600.[22][23] A small colony with about 35 nests was discovered near Bhagalpur in 2006.[1][24]

During the non-breeding season, storks in the Indian region disperse widely, mainly in the Gangetic Plains and sightings from the Deccan region are rare.[25] Records of flocks from further south near Mahabalipuram have been questioned.[18][26] In the 1800s, adjutant storks were extremely common within the city of Calcutta during the summer and rainy season. These aggregations along the Ghats of Calcutta however declined and vanished altogether by the early 1900s. Improved sanitation has been suggested as a cause of their decline.[9][10][27] Birds were recorded in Bangladesh in the 1850s, breeding somewhere in the Sundarbans, but have not been recorded subsequently.[28][29][30]

Behaviour and ecology[edit]

Photographic study of the "martial" gait by Eadweard Muybridge[31] (circa 1887)

The greater adjutant is usually seen singly or in small groups as it stalks about in shallow lakes or drying lake beds and garbage dumps. It is often found in the company of kites and vultures and will sometimes sit hunched still for long durations.[10] They may also hold their wings outstretched, presumably to control their temperature.[32] They soar on thermals using their large outstretched wings.[2]

Breeding[edit]

Greater adjutant stork in breeding plumage, perched near nest (Assam)

The greater adjutant breeds during winter in colonies that may include other large waterbirds such as the spot-billed pelican. The nest is a large platform of twigs placed at the end of a near-horizontal branch of a tall tree.[16] Nests are rarely placed in forks and an unobstructed top canopy allows the birds to fly easily from and to the nests. In the Nagaon nesting colony in Assam, tall Alstonia scholaris and Anthocephalus cadamba were favourite nest trees.[33] The beginning of the breeding season is marked by several birds congregating and trying to occupy a tree. While crowding at these sites, male birds mark out their nesting territories, chasing away others and frequently pointing their bill upwards while clattering them. They may also arch their body and hold their wings half open and drooped. When a female perches nearby, the male plucks fresh twigs and places it before her. The male may also grasp the tarsus of the female with the bill or hold his bill close to her in a preening gesture. A female that has paired holds the bill and head to the breast of the male and the male locks her by holding his bill over her neck. Other displays include simultaneous bill raising and lowering by a pair. The clutch, usually of three or four white eggs,[16] is laid at intervals of one or two days and incubation begins after the first egg is laid. Both parents incubate[34] and the eggs hatch at intervals of one or two days, each taking about 35 days from the date of laying. Adults at the nest have their legs covered with their droppings and this behaviour termed as urohidrosis is believed to aid in cooling during hot weather. Adults may also spread out their wings and shade the chicks. The chicks are fed at the nest for about five months.[35]

Feeding[edit]

An 1855 illustration depicting the stork hunting a snake

The greater adjutant is omnivorous and although mainly a scavenger, it preys on frogs and large insects and will also take birds, reptiles and rodents. It has been known to attack wild ducks coming within reach and swallowing them whole.[36] Their main diet however is carrion and like the vultures their bare head and neck is an adaptation. They are often found on garbage dumps and will feed on animal and human excreta.[37] In 19th-century Calcutta, they fed on partly burnt human corpses disposed along the Ganges river.[38] In Rajasthan, where it is extremely rare, it has been reported to feed on swarms of desert locusts (Schistocerca gregaria)[39] but this has been questioned.[26]

Parasites, diseases and mortality[edit]

At least two species of bird lice, Colpocephalum cooki[40] and Ciconiphilus temporalis[41] have been found as ectoparasites. Healthy adult birds have no natural predators, and the only recorded causes of premature mortality are due to the direct or indirect actions of humans; such as, poisoning, shooting, or electrocution when the birds accidentally fly into overhead electricity wires.[22] Captive birds have been found to be susceptible to avian influenza (H5N1) and high mortality was noted at a facility in Cambodia, with two-thirds of infected birds dying.[42] The longest recorded life span in captivity was 43 years.[43]

Status and conservation[edit]

Loss of nesting and feeding habitat through the draining of wetlands, pollution and disturbance, together with hunting and egg collection in the past has caused a massive decline in the population of this species. The world population was estimated at less than 1,000 individuals in 2008. The greater adjutant is evaluated as Endangered on the IUCN Red List of Threatened Species.[1]

Conservation measures have included attempts to breed them in captivity and to reduce fatalities to young at their natural nesting sites.[35][44] Nearly 15% of the chicks are killed when they fall off the nests and die of starvation, so some conservationists have used nets positioned below the nests to prevent injuries to falling young and then raising these fallen birds in enclosures for about five months before releasing them to join their wild siblings.[4]

In culture[edit]

A view of Calcutta in 1819 by R. Havell, Jr. based on James Baillie Fraser showing a large number of greater adjutants standing on the top of buildings

Aelian described the bird in 250 AD in his De Natura Animalium as the kila, a large bird from India with a crop that looks like a leather bag.[45] In Victorian times the greater adjutant was known as the gigantic crane and later as the Asiatic marabou. It was very common in Calcutta during the rainy season and large numbers could be seen at garbage sites and also standing on the top of buildings. Its local name hargila is derived from the Sanskrit hadda-gilla, which means "bone-swallower",[46] and John Latham used it to give the species the binomial name, Ardea argala.[47] At that time it was a belief that it was protected by the souls of dead Brahmins. The birds in Calcutta were considered to be efficient scavengers and an act was passed to protect them. Anyone who killed the bird had to pay a fine of fifty rupees.[48][49][50] The old emblem of the Calcutta Municipal Corporation included two adjutant storks facing each other.[51] Captured birds, probably from Calcutta reached menageries in Europe during this period.[52][53][54][55]

An Indian myth recorded by the Moghul emperor Babur was that a magic "snake-stone" existed inside the skull of the bird, being an antidote for all snake venoms and poisons.[8][56] This "stone" was supposed to be extremely rare as it could only be obtained by a hunter with great skill, for the bird had to be killed without letting its bill touch the ground in which case the "stone" would evaporate instantly. Folk-medicine practitioners believed that a piece of stork flesh chewed daily with betel could cure leprosy.[57]

References[edit]

  1. ^ a b c BirdLife International (2013). "Leptoptilos dubius". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013. 
  2. ^ a b c Blanford, W. T. (1898). The Fauna of British India, Including Ceylon and Burma. Birds. volume 4. Taylor and Francis, London. pp. 373–374. 
  3. ^ Jerdon, T. C. (1864). The Birds of India 3. George Wyman and Co, Calcutta. pp. 730–732. 
  4. ^ a b Singha, H.; Rahmani, A.R. (2006). "Ecology, population and conservation of greater adjutant Leptoptilos dubius in Assam, India". J. Bombay Nat. Hist. Soc. 103 (2&3): 264–269. 
  5. ^ CRC Handbook of Avian Body Masses by John B. Dunning Jr. (Editor). CRC Press (1992), ISBN 978-0-8493-4258-5.
  6. ^ Hancock, Kushlan & Kahl (1992). Storks, Ibises, and Spoonbills of the World. Academic Press. p. ?. ISBN 978-0-12-322730-0. 
  7. ^ Adam, John (1825). "A description of the Ciconia Argala or Adjutant bird of Bengal.". Trans. Med. Phys. Soc. I., Calcutta: 240–248. 
  8. ^ a b c d Ali, S.; S. D. Ripley (1978). Handbook of the birds of India and Pakistan 1 (2 ed.). Oxford University Press. pp. 105–107. ISBN 0-19-562063-1. 
  9. ^ a b Baker, E. C. S. The Fauna of British India, Including Ceylon and Burma. Birds. Volume 6 (2 ed.). Taylor and Francis, London. pp. 327–329. 
  10. ^ a b c d e Rasmussen, Pamela C.; Anderton, John C. (2005). Birds of South Asia: The Ripley Guide 2. Smithsonian Institution & Lynx Edicions. p. 64. 
  11. ^ Barooah, D. (1991). "Greater Adjutant Stork nesting in upper Assam". Newsletter for Birdwatchers 31 (1&2): 11. 
  12. ^ Blyth, E. (1861). "Notes on the Calcutta 'Adjutant' (Leptoptilus argala)". Ibis 3 (3): 268–270. doi:10.1111/j.1474-919X.1861.tb07459.x. 
  13. ^ Strickland, H. E. (1841). "Commentary on Mr. G R Gray's 'Genera of Birds', 1840". Annals and Magazine of Natural History 7: 26–41. doi:10.1080/03745484109442660. 
  14. ^ Bennett, E. T.; Harvey, W. (1835). The gardens and menagerie of the Zoological Society Delineated. Birds. Volume 2. Thomas Tegg and N. Hailes. pp. 273–278. 
  15. ^ Elliott, A. (1992). "Ciconiidae". In Del Hoyo, J.; Elliott, A.; and Sargatal, J. Handbook of the Birds of the World 1. Barcelona: Lynx Edicions. pp. 436–465. ISBN 8487334105. 
  16. ^ a b c Hume, A. O. (1890). The nests and eggs of Indian birds 3 (2 ed.). R. H. Porter, London. pp. 260–276. 
  17. ^ Bingham, C. T. (1878). "After the Adjutants". Stray Feathers 7: 25–33. 
  18. ^ a b c Rahmani, A. R., Narayan, Goutam; and Rosalind, Lima (1990). "Status of the Greater Adjutant (Leptoptilos dubius) in the Indian Subcontinent". Colonial Waterbirds (Waterbird Society) 13 (2): 139–142. doi:10.2307/1521582. JSTOR 1521582. 
  19. ^ Saikia, P.; Bhattacharjee, P. C. (1990). "Discovery of Greater Adjutant Stork nesting colonies outside the protected areas of Assam, India". Newsletter for Birdwatchers 30 (7&8): 3. 
  20. ^ Raj, M. (1990). "Adjutant Stork Leptoptilos dubius breeding in Nowgaon". Newsletter for Birdwatchers 30 (5&6): 8–9. 
  21. ^ Choudhury, A. (1993). "Nesting colonies of Greater Adjutant Storks in Nagaon and Sibsagar districts of Assam". Newsletter for Birdwatchers 33 (3): 47–48. 
  22. ^ a b Singha, H.; Rahmani, A. R.; Coulter, M. C.; Javed, S. (2003). "Surveys for Greater Adjutant Leptoptilos dubius in the Brahmaputra valley, Assam, India during 1994–1996". Forktail 19: 146–148. 
  23. ^ Oates, Eugene W. (1878). "Notes on the nidification of some Burmese birds, II". Stray Feathers 7: 40–52. 
  24. ^ Mishra A.; Mandal, J. N. (2009). "Discovery of a breeding ground of the Greater Adjutant Leptoptilos dubius and their conservation in the floodplains of Bihar, India". J. Bombay Nat. Hist. Soc. 106 (2): 190–197. 
  25. ^ Burton, R. G. (1921). "The adjutant stork and other matters". J. Bombay Nat. Hist. Soc. 28 (1): 287–288. 
  26. ^ a b Collar, N. J.; Andreev, J. V.; Chan, S.; Crosby, M. J.; Subramanya, S.; Tobias J. A., ed. (2001). Threatened birds of Asia: the BirdLife International Red Data book. BirdLife International, Cambridge. pp. 267–292. 
  27. ^ Dover, C.; Basil-Edwards, S. (1921). "A note on the habits of the Common Pariah Kite (Milvus govinda) and the Adjutant Stork (Leptoptilus dubius)". J. Bombay Nat. Hist. Soc. 27 (3): 633. 
  28. ^ Tytler, R. C. (1854). "Miscellaneous notes on the fauna of Dacca, including remarks made on the line of march from Barrackpore to that station". Ann. Mag. Nat. Hist. 2 (14): 168–177. 
  29. ^ Kahl, M. Philip (1987). "An Overview of the Storks of the World". Colonial Waterbirds (Waterbird Society) 10 (2): 131–134. doi:10.2307/1521251. JSTOR 1521251. 
  30. ^ Luthin, C. S. (1987). "Status of and conservation priorities for the World's stork species". Colonial Waterbirds (Waterbird Society) 10 (2): 181–202. doi:10.2307/1521258. JSTOR 1521258. 
  31. ^ Animal locomotion. The Muybridge work at the University of Pennsylvania. Method and results.. J B Lippincott Company, Philadelphia. 1888. p. 101. 
  32. ^ Kahl, MP (1971). "Spread-wing postures and their possible functions in the Ciconiidae". The Auk 88 (4): 715–722. doi:10.2307/4083833. 
  33. ^ Singha, Hilialjyoti; Rahmani, A. R.; Coulter, M. C.; Javed, S. (2002). "Nesting Ecology of the Greater Adjutant Stork in Assam, India". Waterbirds 25 (2): 214–220. doi:10.1675/1524-4695(2002)025[0214:NEOTGA]2.0.CO;2. ISSN 1524-4695. 
  34. ^ Singha, H.; Rahmani, A. R.; Coulter, M. C.; Javed, S. (2002). "Parental Investment In The Greater Adjutant Stork (Leptoptilos dubius) In The Brahmaputra Valley Of Assam, India". Malayan Nature Journal 56 (3): 239–264. 
  35. ^ a b Singha, H.; Rahmani, A. R.; Coulter, M. C.; Javed, S. (2003). "Breeding behaviour of the greater adjutant-stork Leptoptilos dubius in Assam, India". J. Bombay Nat. Hist. Soc. 100 (1): 9–26. 
  36. ^ Panday, Jamshed D. (1974). "Storks preying on live birds". J. Bombay Nat. Hist. Soc. 71 (1): 141. 
  37. ^ Irby, L. H. (1861). "Notes on birds observed in Oudh and Kumaon". Ibis 3 (2): 217–251. doi:10.1111/j.1474-919X.1861.tb07456.x. 
  38. ^ Strickland, H. E. (1846). "The birds of Calcutta, collected and described by Carl J. Sundevall (translated from Physiographiska sallskapets Tidskrift)". Annals and Magazine of Natural History 18: 87–94. 
  39. ^ Singh, Gurdas; Singh, Charan (1960). "The Adjutant Stork, Leptoptilos dubius(Gmelin), a destroyer of locusts in Rajasthan". J. Bombay Nat. Hist. Soc. 57 (1): 221–222. 
  40. ^ Price, R. D.; Beer J. R. (1965). "The Colpocephalum (Mallophaga: Menoponidae) of the Ciconiiformes" (PDF). Annals of the Entomological Society of America 58 (1): 111–131. 
  41. ^ Price, R. D.; Beer, J. R. (1965). "A Review of Ciconiphilus Bedford (Mallophaga: Menoponidae)". The Canadian Entomologist 97 (6): 657–666. doi:10.4039/Ent97657-6. 
  42. ^ Desvaux, S.; Marx, N.; Ong, S.; Gaidet, N.; Hunt, M.; Manuguerra, J.-C.; Sorn, San; Peiris, Malik; Van der Werf, Sylvie; Reynes, Jean-Marc (2009). "Highly pathogenic avian influenza virus (H5N1) outbreak in captive wild birds and cats, Cambodia". Emerging Infectious Diseases 15 (3): 475–478. doi:10.3201/eid1503.081410. PMC 2681101. PMID 19239769. 
  43. ^ Brouwer, K.; Jones, M. L.; King, C. E.; Schifter, H. (1992). "Longevity and breeding records of storks Ciconiidae in captivity". International Zoo Yearbook 31 (1): 131–139. doi:10.1111/j.1748-1090.1991.tb02376.x. 
  44. ^ Singha, H.; Goswami, S. K.; Phukan, R.; Talukdar, B. K. (2006). "Rehabilitation of captive-reared greater adjutants Leptoptilos dubius in Assam". J. Bombay Nat. Hist. Soc. 103 (2): 315–320. 
  45. ^ Yule, Henry (1903). Hobson-Jobson. A glossary of colloquial Anglo-Indian words and phrases, and of kindred terms, etymological, historical, geographical and discursive (2 ed.). London: John Murray. p. 7. 
  46. ^ Yule, Henry; and Burnell, A. C. (1886). Hobson-Jobson: A glossary of Anglo-India colloquial words and phrases, and of kindred terms. John Murray, London. pp. 4–5. 
  47. ^ Latham, John (1824). A general history of birds 9. Printed by Jacob and Johnson, for the author. pp. 38–41. ISBN 0-665-18204-X. 
  48. ^ Thornton, J. H. (1895). Memories of seven campaigns. Archibald Constable and Co, Westminster. p. 4. 
  49. ^ Roberts, Lord (1901). Forty-one years in India. Macmillan and Co.,London. p. 3. ISBN 1-4021-7742-9. 
  50. ^ "The Calcutta Adjutant". Chambers's Journal of popular literature science and art 15: 40–41. 1861. 
  51. ^ Chaudhuri, Sukanta (2002). View from Calcutta. Orient Blackswan. p. 25. ISBN 81-8028-000-4. 
  52. ^ Stevens, J. C. (1851). A catalogue of the menagerie and aviary at Knowsley, formed by the late Earl of Derby, KG, which will be sold by auction. Joshua Walmsley, Liverpool. p. 41. 
  53. ^ Bennett, E. T. (1831). The gardens and menagerie of the zoological society delineated. Birds. 2. Charles Tilt, London. pp. 273–278. 
  54. ^ Kipling, J. Lockwood (1904). Beast and man in India. Macmillan and Co., London. pp. 37–38. 
  55. ^ Tayler, W. (1881). Thirty-eight years in India. From Juganath to the Himalaya Mountains 1. W. H. Allen, London. pp. 58–64. 
  56. ^ Leslie, J. (1998). "A bird bereaved: The Identity and Significance of Valmiki's Krauñca". Journal of Indian Philosophy 26 (5): 455–487. doi:10.1023/A:1004335910775. 
  57. ^ Ball, Valentine (1880). Jungle life in India. Thomas de la Rue & Co. London. pp. 82–83. 
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