Oriental Darter

The Oriental darter belongs to the Kingdom Animalia, the Phylum is Chordata, the Class is Aves, the Order is Suliformes, the Family is Anhingidae, the Genus is Anhinga, the Binomial name is Anhinga melanogaster.

Measurements
Culmen: 74 to 90 milimetres.
Wing: 331 to 357 milimetres.
Tail: 202 to 240 milimetres.
Tarsus: 42 to 47 milimetres.
Weight: 1,160 to 1,500 grams.

The Oriental darter is also known as the Snakebird, due to its resemblance in appearance to snake, while its plumage is submerged in the water and only long neck and the head is visible.

The colors and other details of the major topographical elements are given below...

Beak: The edges of the commissures of the mandible's tips have minute inward pointing serrations for holding fish. The tip of the Oriental darter's upper mandible is dark while the base is pale brown and the lower mandible is yellowish, the adult female Oriental darter has a shorter bill compared to the adult female Oriental darter.

Head: Brown, black towards the back of the neck. Juvenile Oriental darters have a blackish head or pale brown head.

Iris: White with yellow ring which gets bright in breeding adult Oriental Darters.
Pupil: Black.

Mantle: Grey with grey spots.

Lesser coverts: Grey with wavy or corrugated feathers.

Scapulars: Grey with wavy or corrugated feathers. Immature Oriental darters don't have long pointed scapulars.

Coverts: Grey with wavy or corrugated feathers.

Tertials: Silvery streaks along the shaft, feathers are wavy or corrugated.

Rump: Black.

Primaries: Black with a white edge.

Vent: Blackish brown.

Thigh: Blackish brown.

Tibio-tarsal articulation: Dark grey, yellow in immature Oriental darters and juvenile Oriental darters.

Tarsus: Dark grey, yellow in immature Oriental darters and juvenile Oriental darters.

Feet: Yellow with yellow webbing.

Tibia: Dark grey, yellow in immature Oriental darters and juvenile Oriental darters.

Belly: Blackish brown.

Throat: White with pale line. The male Oriental darter has black speckles on the throat.

Extra Information
The Oriental darter's wing coverts have silvery streaks along the shaft.

The Oriental darter's neck is brown to black to the back of the neck.

The Oriental darter has a pale line over the eye and a line with the sides of the neck.

The Oriental darter has a long and slender neck, wide wings and a wedge shaped tail which can be seen in flight.

The central tail feathers of the Oriental darter are wavy or corrugated.

The Oriental darter's tail is made of twelve stiff feathers which are dragged along the ground when the Oriental darter is walking or hopping.

The juvenile Oriental darter's rear neck is brown and behind the head is blackish. The juvenile Oriental darter's back and tail is black.

The wings of the Oriental darter are black with white feathers.

The rear neck of juveniles is a more pale brown. The underside of their neck is white, but the white lines on the lateral sides of their neck are absent. Darters' white wing feathers are a more yellow-white in juveniles.

Sexual Dimorphism
The adult female Oriental darter has a black base at the neck and chest split from the hind neck because of a wide buff band reaching at the shoulder which immature Oriental darters may also have but with a light neck.

The juvenile Oriental darter or the immature Oriental darter has a pale brown neck and the underparts are whitish, the juvenile Oriental darter or the immature Oriental darter also lack the white streak along the side of the neck.

Muscles
The neck of the Oriental darter has well developed muscles and a bend in the 7th, 8th and 9th vertebrae making it possible to be flexed and darted forward to stab fish underwater.

Adaptations
The Oriental darters feathers are not waterproof causing it to absorb water and be less buoyant making it possible to dive and swim better.

The Oriental darter extends it's wings and paddles with it's webbed feet for swimming.

Oriental darters sit on branches and spread their wings for preening and drying.

The feet of the Oriental darter have four digits.

Sounds
The Oriental darter is silent but at the nest, the Oriental darter does hoarse croak kah-kah-kah, hissing, clickling grunts and a disyllabic chigi-chigi-chigi, the hatchlings or fledglings of the adult female Oriental darter are noisy at begging.

Behaviour
The Oriental darter lives in colonies of hundreds of other Oriental darters which roost in wooded or bamboo groves.

The Oriental darter hunts along with Cormorants.

When a Oriental darter is surprised by a human, it cranes it's neck and flaps it's wings.

The Oriental darter forages alone.

The Oriental darter submerges itself and starts swimming slowly forward with the help of webbed feet while holding it's head and neck above the water.

Oriental darters soar on thermals when it is warm, the Oriental darter alternates flapping and gliding.

The adult Oriental darter roost communally in trees around and over water.

The Oriental darter can dive from it's perch or from it's surface to find or chase fish, some Oriental darters catch fish which come to the surface or swim past, the Oriental darter will dart it's neck to impale the fish, when a fish is impaled by a Oriental darter then it will come to the surface to throw the fish up and swallow it by the head, sometimes the fish are swallowed in the water.

Diet
Insects, turtles, snakes, frogs, newts, shrimp, mollusks, sponges, echinoderms, aquatic crustaceans, nuts, plant grasses and seeds in small quantities. plant material maybe accidental eaten by Oriental darters.

Habitat
Freshwater lakes and streams and is found along cormorants, tree thickets, bamboo thickets, deep estuaries, lakes, ponds and marshes. the Oriental darter spreads it's wings on a waterside rock or tree.

Distribution
They are found in most parts of India.

Breeding & Nesting
The Oriental darter is monogamous.

The adult male Oriental darter and the adult female Oriental darter communicate by wing flapping displays.

The Oriental darter lives near and nests near colonies of cormorants and herons.

The adult male Oriental darter and the adult female Oriental darter make a stick platform of 40 to 50 centimetres diameter and lined with leaves.

The Oriental darters nest is on trees over and around water and it can be reused for years.

the Oriental darter makes it's nest around several pairs of other Oriental darters. The branch used for the nest of the Oriental darter is flattened in advanced for the sticks that form the platform.

The Oriental darter defends it's nest with postures, hopping, hissing, snapping and thrusts of the neck.

The Oriental darters breeding season is June to August in northern India, April to May in southwestern India and winter in southeastern India. The breeding season depends on water levels to be high and fish to be abundant.

The adult female Oriental darter lays three to six spindle shaped bluish-green eggs with a white chalky covering which will be covered in soil, the average number of eggs is three.

The adult male Oriental darter and the adult female Oriental darter start incubating after the first egg leading to asynchronous hatching.

The eggs are incubated for 25 to 30 days, the average hatching period is 28 days.

The hatchlings of the adult female Oriental darter are bare with few downy feathers on their head. The hatchlings of the adult female Oriental darter acquire a white down feathers on their body.

The hatchlings or fledglings of the adult female Oriental darter get food by thrusting their heads in the throat of the adult male Oriental darter or adult female Oriental darter.

The hatchlings of the adult female Oriental darter become fledglings in just 50 minutes.

The fledglings of the adult female Oriental darter become independent at 50 days of age and become mature in 2 years of age.

The adult male Oriental darter and adult female Oriental darter regurgitate food 6 to 9 times a day for a few weeks.

Moulting
The adult Oriental darter does a synchronous moult of it's flight feathers after the breeding season making the Oriental darter flightless for sometime.

Oriental darters will dive from a perch if they get disturbed during their moulting, hatchlings and fledglings of the adult female Oriental darter also dive for safety.

Lifespan
9 years.

Threats
The hatchlings, fledglings or Oriental darters which have grown for than half are preyed on by Pallas's fish eagle.

Draining bodies of water, cutting down trees, intrusion of breeding and feeding areas, egg collection, hunting, and pollution by chemical runoff or algal blooms.

Diseases
Schwartzitrema anhingi, Contracaecum rudolphii, Contracaecum carlislei, Petasiger nicolli, Contracaecum tricuspis, Mesorchis pendulus, Contracaecum microcephalum and Echinorhynchotaenia tritesticulata.

Population
22000, decreasing (Near Threatened Status)