26.04.2023 - Lesser Adjutant (Leptoptilus javanicus)

Name: Lesser Adjutant
Scientific Name: Leptoptilus javanicus
Tamil Name: சிறிய போதா நாரை(Siriya Poathaa Naarai)

Malay/Local Name: Burung Botak Kecil

Lesser Adjutant wading at the intertidal mudflats in Jeram, Selangor.

For those who are not familiar to this stork species, its certainly a weird bird with an eerie look. Lesser adjutant is the smallest member of the Adjutant family, which at seen foraging at the intertidal mudflats and rice fields. It is a large bird with bare neck and head and comes with a big dagger like bill. Its genus, "Leptoptilus" means "delicate feather", probably describing the delicate hair like feathers on its bare head and neck. Its species name, "javanicus" indicates the location where the first specimen was described. The Malay name was derived from its obvious characteristics and described for being the smallest among the three species of Leptoptilus storks.

Lesser Adjutant from Sungai Balang Rice Field, Johor.

Description:

Adult adjutant appears with a blue-black upperpart and white underpart, with pinkish bare skin on the head and neck, which are barely covered with scattered hair like feathers. Bill is horn-colored and legs are grey. Eyes are bluish. Despite of its larger size and heavier bill, the male adjutant looks similar to the female in plumage. Juveniles appears as the duller version of the adults, with more feathers on its nape. During its breeding season, the bare part of its head and neck of the breeding adults turns brighter. A full grown Lesser Adjutant stands about 1.1m to 1.2m tall, with a wingspan up to 2.1m. Hybridization do occur in nature due to overlapping breeding range as well as in captivity, with Painted Storks. 

Closer look of Lesser Adjutant

Status and Distribution:

Common to scarce resident of Peninsular Malaysia, Sabah, and Sarawak. In Peninsular Malaysia, Lesser Adjutants are can be seen at coastal mangroves of Perak (Kuala Gula, Kuala Sepetang, Bagan Datok, Ulu Dedap rice filed), Selangor (North Central Selangor Coast), Johor (South Western Coast, Sungai Balang, Bukit Gambir), Pahang (Pekan) and Penang (Teluk Air Tawar). In East Malaysia, the bird can be seen on North-Eastern and North-Western coasts of Sabah; Pulau Beruit and Maludam National Park of Sarawak.

Some sightings of Lesser Adjutant by our local birders.

Lesser Adjutant just landed at the intertidal mudflats of Jeram, Selangor

Lesser Adjutant prowling at the Jeram mudflats, Selangor

Lesser Adjutants from Kemang Tasik Rice Field, Johor. [Photo Credit: Ahmad Taufik]

Confusion Species:

None

Geographical Variation:

None

Behavior:

Forages alone or in small loose groups at the intertidal flats adjacent to coastal mangroves and rice fields. Lesser Adjutants feeds on fish, frogs, snakes, large invertebrates, and other smaller water birds. Also picks on carcasses. Hunting is done by both visual and non visual methods. As for the visual hunting method, the bird seen to pursue moving preys on the surface of the mudflat while using its wings to balance itself. The prey is grabbed with its beak and tossed before swallowing.  For its non-visual hunting, it captures its prey by repeatedly probing its slightly gapped bill into to the mud. Sometimes it plunges the whole head and partially its neck into the mud and this may indicate its strong neck anatomy. Observed continuously gnawing the mud as well to extract prey items. The captured prey is tossed and swallowed whole. Also observed to wash mud covered prey before consuming. Often seen thermaling above its habitat, sometimes along with other storks or raptors. Mostly silent; bill clattering, hissing and moaning sounds have been noted at the nests. 

Lesser Adjutant with a catch at Sungai Muar, Johor. [Photo Credit: Ahmad Taufik]

Lesser Adjutant with an eel at Jeram mudflats, Selangor

Lesser Adjutant gulping a White Breasted Waterhen, at Wasan Rice Field, Brunei. [Photo Credit: Husini Bakar]

Lesser Adjutant about to land on the Jeram mudflats, Selangor.

Lesser Adjutant thermaling above Parit Jawa coast, Johor

Habitat:
Coastal wetlands, freshwater wetlands, and rice fields.

Breeding:

In Peninsular Malaysia, breeding season are recorded between January to June. It breeds once a year. Lesser Adjutants are tree nesters and prefer tall (even dead) emerging trees in secluded mangroves and freshwater swamps. It also nest at abandoned plantations, forming a small scaled colony. Its nest are large yet rather flimsy looking, made with sticks and lined with smaller twigs and green leaves. Nests are re-used by adding more sticks to it. 

Nest is constructed by both male and female adjutants. Courtship is lengthy; starts 3 months before the first egg is laid. Male selects the nesting spot; indicating the spot by carrying a twig. Two to four (mostly three) white eggs are laid in 1 to 3 days intervals and incubated by both male and female for 28 to 30 days. The parent birds had been seen to shade the young by spreading their wings and to bring water to the chicks during hot weather. The young birds fledge in 47 to 52 days, and will be fully independent at 5 months old.

Hybrids:

Recorded in both nature and captivity. with Painted Stork. The hybrid had the look and size of a Painted Stork along with greyish body and dark grey wings, which resembles the Lesser Adjutant.

Conservation Status:

Lesser Adjutants are classified as "Vulnerable" under IUCN Red List of Threatened Species, with less than 250 individual birds surviving in Peninsular Malaysia. Although globally its facing population decline due to habitat loss, overhunting and human disturbance, Lesser Adjutants in Malaysia are facing threat due to the degradation of habitat and habitat loss primarily. Large, open trees in the mangroves are chosen by the adjutants for nesting and for high tide roosting. When large trees are logged in the mangroves, it will take time for those smaller trees to grow to that useful size for the adjutants to nest or to roost. The situation goes even worst when logging is done illegally. It will gradually reduce the number of large trees and thus reduce the number successful breeding of this adjutant. 

When this happens, the adjutants may move away from that habitat to find new potential breeding grounds, which is will reduce its number in the original habitat. There are records of nesting had been made much further away from the coastal mangroves in an abandoned rubber estate in the state of Johor. This may had happened due to lack of suitable trees in the mangroves. There is a study done on nesting characteristics of Lesser Adjutants in Nepal, which mentions the species makes choices based on the tree characteristics instead of the tree locations. When the adjutants started to nest near to human settlements, there are chances for it to be exposed to new threats, i.e., nesting trees can be removed by people in response to the nuisance of nesting birds.  The coastal mangroves also face threats from land reclamation for water front developments as well. 

I had found some things lacking about the Lesser Adjutant conservation here in Malaysia:

• Lack of latest data on population and population trend for the past 10 years for Lesser Adjutant.
• No national level programs related public awareness of conservation of Lesser Adjutants, at least to those who are living closer to its habitat. Such programs are not documented and followed up properly, if it has been executed.
• No cost and manpower related data proposed for the conservation measures of Lesser Adjutants, for a much realistic and workable solution. Continuity is lacking.

A much positive approach need to be planned by the authorities and NGOs to save these birds. Most bird enthusiasts emphasized on one point as a plan to save this bird: "Protect the mangroves!". 

   References:

1. Katuwal H. B., Sundar KS. G., Zhang M., Rimal B., Baral H. S., Sharma H. P., Ghimire P., Hughes A. C. and Quan R. C. (2022) Factors Affecting the Breeding Ecology of the Globally Threatened Lesser Adjutant, Avian Conservtion and Ecology.
2. Subaraj R. and Lok F. S. L (2009) Status of Lesser Adjutant in Singapore, Nature In Singapore
3. BirdLife Internation - Data Zone (2023), Lesser Adjutant, http://datazone.birdlife.org/species/factsheet/lesser-adjutant-leptoptilos-javanicus/text

Special Thanks (for Photos and Data):

1. Ang Teck Hin (Malacca)
2. Ahmad Taufik (Johor)
3. Premala Arulambalam-Gehri & Adrian Gehri (Sabah)
4. Husini Bakar (Brunei)
5. Terence Ang (Selangor)
6. Mohd Sidek Noorwi (Perak)