PLEASE! If you see any mistakes, I'm 100% sure that I have wrongly identified some birds.
So please let me know on my guestbook at the bottom of the page
Asian Openbill Stork, Anastomus oscitans

The Asian Openbill or Asian Openbill Stork (Anastomus oscitans) is a large wading bird in the stork family Ciconiidae. This distinctive stork is found mainly in the Indian subcontinent and Southeast Asia. It is greyish or white with glossy black wings and tail and the adults have a gap between the arched upper mandible and recurved lower mandible.

Young birds are born without this gap which is thought to be an adaptation that aids in the handling of snails, their main prey. Although resident within their range, they make long distance movements in response to weather and food availability.

Habitat and distribution
The usual foraging habitats are inland wetlands and are only rarely seen along river banks and tidal flats. On agricultural landscapes, birds forage in crop fields, irrigation canals, and in seasonal marshes. Birds may move widely in response to habitat conditions.

Young birds also disperse widely after fledging. Individuals ringed at Bharatpur in India have been recovered 800 km east and a bird ringed in Thailand has been recovered 1500 km west in Bangladesh. Storks are regularly disoriented by lighthouses along the southeast coast of India on overcast nights between August and september.

The species is very rare in the Sind and Punjab regions of Pakistan, but widespread and common in India, Sri Lanka, Burma and Thailand.

Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
The Distribution of the Asian Openbill
By Nrg800 - Natural Earth and Myself, CC BY-SA 3.0, Link

Description
The Asian Openbill Stork is predominantly greyish (non-breeding season) or white (breeding season) with glossy black wings and tail that have a green or purple sheen. The name is derived from the distinctive gap formed between the recurved lower and arched upper mandible of the beak in adult birds.

Young birds do not have this gap. The cutting edges of the mandible have a fine brush like structure that is thought to give them better grip on the shells of snails.

Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
Baby Asian Openbill with no gap in the bill
Chedi--paddies N of Song Phi Nong Canal, Thailand - 28 May 2022

The tail consists of twelve feathers and the preen gland has a tuft. The mantle is black and the bill is horn-grey. At a distance, they can appear somewhat like a white stork or Oriental stork. The short legs are pinkish to grey, reddish prior to breeding. Non-breeding birds have a smoky grey wings and back instead of white. Young birds are brownish-grey and have a brownish mantle.

Like other storks, the Asian Openbill is a broad-winged soaring bird, which relies on moving between thermals of hot air for sustained flight. They are usually found in flocks but single birds are not uncommon. Like all storks, it flies with its neck outstretched. It is relatively small for a stork and stands at 68 cm height (81 cm long)

Length: 81 cm
Wingspan: 147 - 149 cm
Weight:
Longevity:
Distinctive Feature

Similar Species



From opus at www.birdforum.net
Female / Male / Juvenile

• Non-breeding adult: off-white plumage
• Young birds plumage has a brown tinge

From opus at www.birdforum.net


Listen to the Asian Openbill Stork

Remarks from the Recordist

Loud calls of pulli in the nests of a breeding colony.


www.xeno-canto.org

Food and foraging
During the warmer part of the day, Asian Openbills soar on thermals and have a habit of descending rapidly into their feeding areas. Groups may forage together in close proximity in shallow water or marshy ground on which they may walk with a slow and steady gait.

The Asian Openbill feeds mainly on large molluscs, especially Pila species, and they separate the shell from the body of the snail using the tip of the beak. The tip of the lower mandible of the beak is often twisted to the right.

This tip is inserted into the opening of the snail and the body is extracted with the bill still under water. Jerdon noted that they were able to capture snails even when blindfolded. The exact action being difficult to see, led to considerable speculation on the method used.

Sir Julian Huxley examined the evidence from specimens and literature and came to the conclusion that the bill gap was used like a nutcracker.

He held the rough edges of the bill as being the result of wear and tear from such actions. Subsequent studies have dismissed this idea and the rough edge of the bill has been suggested as being an adaptation to help handle hard and slippery shells.


Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
Asian Openbill have found a big snail
Petchaburi Rice Field, Thailand - June 2020

Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
Asian Openbill have found a big snail
Petchaburi Rice Field, Thailand - June 2020

Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
Asian Openbill struggling to open a big snail
Petchaburi Rice Field, Thailand - June 2020

Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
Asian Openbill struggling to open a big snail
Petchaburi Rice Field, Thailand - June 2020


They forage for prey by holding their bill tips slightly apart and make rapid vertical jabs in shallow water often with the head and neck partially submerged. The gap in the bill is not used for handling snail shells and forms only with age. Young birds that lack a gap are still able to forage on snails.

It has been suggested that the gap allows the tips to strike at a greater angle to increases the force that the tips can apply on snail shells. Smaller snails are often swallowed whole or crushed.

They also feed on water snakes, frogs and large insects. When foraging on agricultural landscapes with a variety of habitats, Asian Openbills preferially use natural marshes and lakes (especially in the monsoon and winter), and irrigation canals (especially in the summer) as foraging habitat.

Breeding
The breeding season is after the rains, during July to September in northern India and Nepal, and November to March in southern India and Sri Lanka. They may skip breeding in drought years.

The Asian Openbill breeds colonially, building a rough platform of sticks often on half-submerged trees (often Barringtonia, Avicennia and Acacia species), typically laying two to four eggs.

The nesting trees are either shared with those of egrets, cormorants and darters, or can be single-species colonies like in lowland Nepal.

Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
Many Asian Openbills in same tree- Siting on eggs and some nest with babies
Bangkok April 2022 - Click picture to get full size

Nesting colonies are sometimes in highly disturbed areas such as inside villages and on trees located in crop fields. In lowland Nepal, 13 colonies found in an agricultural lansdscape had an average colony size of 52, ranging from 5 nests to 130 nests. The nests are close to each other leading to considerable jostling among neighbours.

Both parents take turns in incubation, the eggs hatching after about 25 days. The chicks emerge with cream coloured down and are shaded by the loosely outspread and drooped wings of a parent.

Adult Asian Openbills in Nepal took an average of 27 minutes to return to nests with food for nestlings and fledglings. The time taken to find food was most impacted by the location of wetlands around colonies, and the progression of the breeding season.

Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
Asian Openbill sitting on egg
Bangkok April 2022

Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
Asian Openbill sitting on egg
Bangkok April 2022

Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
Asian Openbill sitting on egg
Bangkok April 2022

Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
Asian Openbill with baby
Bangkok April 2022

Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
Asian Openbill with babies
Bangkok April 2022

Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
Asian Openbill with babies
Bangkok April 2022

Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
Young ones in the nest
Bangkok April 2022

Adults look the least time to return with food earlier in the season when the dominant rice crop was most flooded, and time increased as the rice ripened along with the drying out of the fields.

Like other storks, they are silent except for clattering produced by the striking of the male's bill against that of the female during copulation. They also produce low honking notes accompanied by up and down movements of the bill when greeting a partner arriving at the nest.

Males may sometimes form polygynous associations, typically with two females which may lay their eggs in the same nest.

Asian Openbill collect nesting material
Bangkok April 2022


Relationship with other organisms
Young birds at the nest are sometimes preyed on by imperial, steppe and greater spotted eagles. Chaunocephalus ferox, an intestinal parasite, is a trematode worm found in about 80% of the wild populations in Thailand while another species Echinoparyphium oscitansi has been described from Asian Openbills in Thailand.

Other helminth parasites such as Thapariella anastomusa, T. oesophagiala and T. udaipurensis have been described from the oesophagus of storks.

In colonial India, sportsmen shot the openbill for meat, calling it the “beef-steak bird”



Conservation status
Asian Openbill Stork, Anastomus oscitans
Least Concern (IUCN 3.1)
IUCN Red List of Threatened Species. Version 2013.2.
International Union for Conservation of Nature. Retrieved 26 November 2013.



From Wikipedia, the free encyclopedia
From Wikipedia, the free encyclopedia

www.birdforum.net


Sighted: (Date of first photo that I could use) 18th of January 2016
Location: Ranthambhore National Park


PLEASE! As I'm a first time birdwatcher bear in mind that some of the bird can be wrongly named. I have bought books and I confirm on the internet to get the right identity on the birds I take pictures off. But there can still be mistakes.

Among others I have used Peter Ericsson's web page Birds of Thailand These galleries contain 668 species of the Birds of Thailand and have been of a great help to identify some of the birds.

Asian Openbill Stork, Anastomus oscitans
Asian Openbill Stork / นกปากห่าง
18 January 2016 - Ranthambhore National Park, Indo

Asian Openbill Stork, Anastomus oscitans
Asian Openbill Stork / นกปากห่าง
18 January 2016 - Ranthambhore National Park, Indo

Asian Openbill Stork, Anastomus oscitans
Asian Openbill Stork / นกปากห่าง
18 January 2016 - Ranthambhore National Park, Indo

Asian Openbill Stork, Anastomus oscitans
Asian Openbill Stork / นกปากห่าง
29 January 2016 - Kanha National Park, India

Asian Openbill Stork, Anastomus oscitans
Asian Openbill Stork / นกปากห่าง
29 January 2016 - Kanha National Park, India

Asian Openbill Stork, Anastomus oscitans
Asian Openbill Stork / นกปากห่าง
30 January 2016 - Kanha National Park, India

Asian Openbill Stork, Anastomus oscitans
Asian Openbill Stork / นกปากห่าง
30 January 2016 - Kanha National Park, India

Asian Openbill Stork, Anastomus oscitans
Asian Openbill Stork / นกปากห่าง
30 January 2016 - Kanha National Park, India

Asian Openbill Stork, Anastomus oscitans
Asian Openbill Stork / นกปากห่าง
30 January 2016 - Kanha National Park, India

Asian Openbill Stork, Anastomus oscitans
Asian Openbill Stork / นกปากห่าง
30 January 2016 - Kanha National Park, India

Asian Openbill Stork, Anastomus oscitans
Asian Openbill Stork / นกปากห่าง
30 January 2016 - Kanha National Park, India

Asian Openbill Stork, Anastomus oscitans
Asian Openbill Stork / นกปากห่าง
30 January 2016 - Kanha National Park, India

Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
Asian Openbill Stork / นกปากห่าง
16 May 2017 - Yala National Park, Sri Lanka

Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
Asian Openbill Stork / นกปากห่าง
16 May 2017 - Yala National Park, Sri Lanka

Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
Asian Openbill Stork / นกปากห่าง
16 May 2017 - Yala National Park, Sri Lanka

Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
Asian Openbill Stork / นกปากห่าง
16 May 2017 - Yala National Park, Sri Lanka

Asian Openbill Stork, Anastomus oscitans, นกปากห่าง
Asian Openbill Stork / นกปากห่าง
16 May 2017 - Yala National Park, Sri Lanka



PLEASE! If I have made any mistakes identifying any bird, PLEASE let me know on my guestbook



       
                  



                                       

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