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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.
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.
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)
Loud calls of pulli in the nests of a breeding colony.
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 have found a big snail
Phetchaburi Rice Field, Thailand - June 2020
Asian Openbill have found a big snail
Phetchaburi Rice Field, Thailand - June 2020
Asian Openbill struggling to open a big snail
Phetchaburi Rice Field, Thailand - June 2020
Asian Openbill struggling to open a big snail
Phetchaburi 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.
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 sitting on egg
Bangkok April 2022
Asian Openbill sitting on egg
Bangkok April 2022
Asian Openbill sitting on egg
Bangkok April 2022
Asian Openbill with baby
Bangkok April 2022
Asian Openbill with babies
Bangkok April 2022
Asian Openbill with babies
Bangkok April 2022
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”
Sighted: (Date of first photo that I could use)
21st of December 2015 Location: Red lotus Sea in Udon Thani
Visit Nick Upton atwww.thaibirding.comfor HOT birding tips for sites around Bangkok and Thailand. There are reviews of the birding sites with maps and information.
And if you like Nick Upton's web page you will also likewww.norththailandbirding.comI have used this page together with Nick Upton's page when planning my birding tours. Excellent reviews and information about the birding sites.
I also got the Thai names of the birds from www.norththailandbirding.com. There is a bird check list with all the names in English and Thai. And of course also the Scientific Name. Down load the birdlist in Microsoft Excel format atwww.norththailandbirding.comOr down load the Excel sheet by clickingHERE
And my new aid, maybe, and I say maybe the best aid. I brought my mobile phone as my SIM card have stopped working and I tried to get it to work again so I can use the internet. Thus I had my phone in my pocket on my first game drive in Jim Corbett National Park.
We saw a bird and I asked my Guide and the driver if they had a pen and a paper as I had forgot my pen and paper in my room. I remembered my LG phone and I recorded the name. And thus I will always bring my phone. Writing the name in the car and I have found more than once that it can be hard to read what I had wrote when I'm back in my room.
So now I always have my mobile in my pocket and it has been a great help. And from November 2018 I use eBird. Bird watching in U.A.E and Oman and my guide in Dubai recommended eBird and I have used the app since then and I note every bird I can identify in my eBird app.
Asian Openbill Stork / นกปากห่าง - 21 December 2015 - Red Lotus Sea in Udon Thani, Thailand
Asian Openbill Stork / นกปากห่าง - 1 January 2016 - Suan Rot Fai/ Queen Sirikit Park, Bangkok
Asian Openbill Stork / นกปากห่าง - 1 January 2016 - Suan Rot Fai/ Queen Sirikit Park, Bangkok
Asian Openbill Stork / นกปากห่าง - 1 January 2016 - Suan Rot Fai/ Queen Sirikit Park, Bangkok
Asian Openbill Stork / นกปากห่าง - 1 January 2016 - Suan Rot Fai/ Queen Sirikit Park, Bangkok
Asian Openbill Stork / นกปากห่าง - 12 February 2016 - Bang Pu, Bangkok
Asian Openbill Stork / นกปากห่าง - 12 February 2016 - Bang Pu, Bangkok
Asian Openbill Stork / นกปากห่าง - 12 February 2016 - Bang Pu, Bangkok
Asian Openbill Stork / นกปากห่าง - 12 February 2016 - Bang Pu, Bangkok
Asian Openbill Stork / นกปากห่าง - 12 February 2016 - Bang Pu, Bangkok
Asian Openbill Stork / นกปากห่าง - 13 February 2016 - Phetchaburi Rice Field
Asian Openbill Stork / นกปากห่าง - 13 February 2016 - Phetchaburi Rice Field
Asian Openbill Stork / นกปากห่าง - 13 February 2016 - Phetchaburi Rice Field
Asian Openbill Stork / นกปากห่าง - 13 February 2016 - Phetchaburi Rice Field
Asian Openbill Stork / นกปากห่าง - 13 February 2016 - Phetchaburi Rice Field
Asian Openbill Stork / นกปากห่าง - 10 July 2016 - Suan Rot Fai, Bangkok
Asian Openbill Stork / นกปากห่าง - 10 July 2016 - Suan Rot Fai, Bangkok
Asian Openbill Stork / นกปากห่าง - 24 August 2018 - Bang Pra Non-hunting Area
Asian Openbill Stork / นกปากห่าง - 6 June 2019 - Suan Rot Fai, Bangkok
Asian Openbill Stork / นกปากห่าง - 6 June 2019 - Suan Rot Fai, Bangkok
Asian Openbill Stork / นกปากห่าง - 1 May 2020 - Praek Nam Daeng, Samut Songkhram
Asian Openbill Stork / นกปากห่าง - 26 July 2020 eBird hotspot: Mahidol University [Salaya Campus] & Sireeruckhachart Botanical Garden
Asian Openbill Stork / นกปากห่าง - 26 July 2020 eBird hotspot: Mahidol University [Salaya Campus] & Sireeruckhachart Botanical Garden
Asian Openbill Stork / นกปากห่าง - 26 July 2020 eBird hotspot: Mahidol University [Salaya Campus] & Sireeruckhachart Botanical Garden
Asian Openbill Stork / นกปากห่าง - 26 July 2020 eBird hotspot: Mahidol University [Salaya Campus] & Sireeruckhachart Botanical Garden
Asian Openbill Stork / นกปากห่าง - 26 July 2020 eBird hotspot: Mahidol University [Salaya Campus] & Sireeruckhachart Botanical Garden
Asian Openbill Stork / นกปากห่าง - 26 July 2020 eBird hotspot: Mahidol University [Salaya Campus] & Sireeruckhachart Botanical Garden
Asian Openbill Stork / นกปากห่าง - 26 July 2020 eBird hotspot: Mahidol University [Salaya Campus] & Sireeruckhachart Botanical Garden
PLEASE! If I have made any mistakes identifying any bird, PLEASE let me know on my guestbook