Milky Stork

Milky Stork
Mycteria cinerea

Ciconiiformes Order – Ciconiidae family

INTRODUCTION:
The Milky Stork is included in the tribe Mycteriini, characterized by birds of smallish size that breed in colonies, and with specialized bills and feeding techniques. The long, tapered bill is slightly decurved and has sensitive areas towards the tip, allowing the bird to feed under different conditions than other Ciconiidae. It often immerses the whole bill and the head in the mud to reach preys hidden in holes. In these cases, the capture is tactile.
This large waterbird has restricted range in SE Asia where it can be found on tidal mudflats for foraging, and in mangroves for nesting.
The Milky Stork is very sensitive to human disturbance, but fishing, hunting and forest activities have a negative impact on breeding success and population. This species is currently listed as Endangered.

DESCRIPTION OF THE BIRD:
Biometrics:
Length: 92-97 cm

The Milky Stork adult in breeding plumage has black flight feathers and rectrices contrasting with the white body suffused with very pale creamy-buffy.
The long bill is bright yellow to orange-yellow. The bare facial skin is bright red. Legs and feet are deep red. The eyes are dark brown, surrounded by narrow red-orange eyering, and a circular whitish area.

The non-breeding adult has all white plumage except blackish primaries, secondaries and tail.
The bill is pale pinkish-yellow. The bare facial skin becomes dark, dull reddish, with black areas around the base of the bill, and dull pinkish eye’s area. Legs and feet are dull pinkish-red.
Male and female are similar.

The juvenile is greyer overall. Head and neck are browner and more uniform. On the upperwing, lesser and median coverts are paler and contrast with the mantle. The bare facial skin is slightly less extensive than in adults.

RANGE:
The Milky Stork is confined to SE Asia and occurs in Cambodia, W Peninsula Malaysia, Sumatra, Java and Sulawesi.

HABITAT:
The Milky Stork is a coastal species and forages on tidal mudflats, saline pools, ricefields and freshwater marshes. It nests in mangroves and swamp forest.
It may occur occasionally in inland flooded forest in Cambodia.

CALLS AND SONGS: SOUNDS BY XENO-CANTO
The Milky Stork is silent away from the colonies. However, it produces some non-vocal sounds during the “up-down” display, usually a hissing “fizz”. The typical bill-clattering is performed during both courtship and copulation.
The begging call by chicks is a frog-like sound.

BEHAVIOUR IN THE WILD:
The Milky Stork feeds on various aquatic preys such as mudskippers (Periophthalmus) and small fish. It also takes snakes, frogs, crustaceans and aquatic insects.
It forages on tidal mudflats and in shallow water where it can find dense concentration of fish. Thanks to its highly specialized feeding behaviour, it is able to catch preys by touching with the bill tip both in water and mud.

The Milky Stork stands or walks slowly while moving its submerged bill from side to side. It also stirs up the mud of the bottom and the water with one foot, in order to disturb the preys hidden in the mud. It also flashes its wings open over the water for the same reason.
As soon as the bill comes into contact with a prey, it is immediately shut on and once caught, the prey rarely escapes.
When a mudskipper is caught, it is hauled out and tossed up in the air, to be finally swallowed head first.

The Milky Stork performs typical courtship displays, including greeting displays at nest with bowing, upwards-stretching and bill-raising, touching and crossing, accompanied by bill-clattering. Other displays such as “display-preening”, “flying around” and “gaping” are used to confirm the pair-bond. Copulation is frequent during nest-building, and occurs usually on the nest. This species is highly gregarious and breeds in colonies.

The Milky Stork is resident, but it may occur as non-breeding visitor in Bali. The storks perform some seasonal movements outside breeding season. They are vagrant to Thailand and Vietnam. The movements are probably related to water levels and prey availability.

The Milky Stork flies with neck and legs outstretched. The long, broad wings are suited for soaring.

REPRODUCTION OF THIS SPECIES:
The breeding season takes place between August and December, with peak during the dry season.
The Milky Stork nests in colonies established in large trees. The stick nest is a large, flimsy platform placed 8-10 metres above the ground.

The female lays 3-4 white eggs that become usually very dirty. Both adults share the incubation during 25-38 days (the duration is unknown). At hatching, the chicks have white down, dark bill and facial skin. They are fed by both parents, mainly with prawns (Penaeus indicus and P. merguensis) and small fish of 7-10 centimetres long. The food is regurgitated on the nest’s floor where all the chicks can take it. They fledge at least 50 days after hatching, but probably more. They still depend on adults for some weeks more.

PROTECTION / THREATS / STATUS:
The Milky Stork is mainly threatened by habitat loss through destruction of tidal forest and mangroves in Indonesia for agriculture expansion and other developments such as fish-farms and rice cultivation, logging and related disturbances. Hunting pressure for food occurs throughout the range.
In Malaysia, the birds suffer from persecution and disturbance at colonies. In Cambodia, eggs, chicks and adults suffer from exploitation for food and trade, with in addition, the loss of flooded forest.

The global population is estimated at less than 5,000 individuals, equating to about 3,300 mature individuals. This population is declining rapidly due to the previous threats.
Some colonies are established in protected areas in Sumatra, Java, Malaysia and Cambodia.
A captive breeding and reintroduction programme is in progress in Malaysia.
But currently, the Milky Stork is listed as Endangered.