Tracking the Asian Openbill invasion

Prior to 1 March 2008, Asian Openbill Anastomus oscitans was unknown in Malaysia. That was the day Lim Kim Chye and Lim Swee Yian spotted one improbably perched in a clump of trees in a sugar cane plantation in Perlis. The bird quickly departed, and that was apparently that, until 2 years later, almost to the day, M Hakim found 4 birds roosting in some paddyfields in Seberang Prai, Penang.

This little flock built up to around 10 birds, and stayed in the area till the end of April 2010. In August the same year, 5 of them were back, departing at the end of Feb 2011. Back they came again in August 2011, and it seemed that their presence had settled into a more or less predictable pattern. However, these birds were last seen in October 2011, and none at all were seen the following year.

One might have expected a gradual trickle of further records in the north of the peninsula, but nothing prepared us for what was to begin on 8-9 January this year, when about a thousand were seen circling over Kuala Gula in Perak, 240 turned up in Batang Tiga, Melaka, and 300 were seen over Penanti, Penang. From then on, it became progessively obvious that a full scale ‘invasion’ was underway, and it became difficult to track exactly which flocks were new arrivals and which were part of the original vanguard.

Flocks of 100-200 became relatively commonplace, with sightings concentrated in the main rice-growing areas of the west coast, from Perlis, Kedah and Pulau Pinang in the north, Perak and Selangor in the centre, and Melaka and Johor in the south. Up to 8 birds even reached Singapore briefly.

So far, the main concentration seems to be in Penang and Kedah, with a group of up to 3,000 birds estimated in April in northern mainland Penang  – the first 4 figure report since the initial Kuala Gula sighting.

Why are they here? Asian Openbill populations in South-east Asia have been doing well in general, largely due to the infestation of paddyfields of the Golden Apple snail, which has spread southwards via irrigation canals. Expansion of populations of Asian Openbill has put pressure on existing breeding colonies, causing birds to wander ever further afield to look for potential new sites. However, this might be expected to lead to a gradual increase in records, rather than this sudden upsurge. A more likely explanation is that the floods which inundated Central Thailand to the height of several feet of water in 2011 hit the snail population badly, leading to a food shortage for the storks breeding in this area. This has apparently caused some colonies to abandon their traditonal sites.

In June, a roost site was located on the Penang-Kedah border, so, on 13 July, I took my daughters there to do a timed count of birds coming to roost. IMG_4468

The site is some abandoned sand-mining pools surrounded by Acacia and other pioneer tree species and thick scrub.


By the time we arrived at 4.15pm, we counted about 100 birds already in residence.


We counted birds arriving for the next 3 hours. Neither of my girls particularly like birding, but they are hooked on bird counting! That’s one of the benefits of going to Raptor Watch at Tanjung Tuan in March I guess! All I had to do was point out the flocks as they arrived and my eldest daughter with her ‘clicker’ did the rest!IMG_4481

The skies were threatening rain, and it finally poured. Once the rain stopped, the birds started arriving in big numbers. They had obviously been waiting for the rain to pass.

IMG_2633 IMG_2628IMG_2621

By the time we had finished, we’d counted 3,874 birds, and more were arriving as we left.

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Such a prominent spectacle is bound to attract attention, both for good and bad. While we were there we heard three shots from two different locations, and met a local person who told us that the birds weigh 1-2kg! Now how would he know that?!

He told us that all the farmers know these birds are good news for them, as their main food is the Godlen Apple snail. Nevertheless, a few people obviously find the temptation of openbill meat too much! One could argue that the killing of a few birds among so many is not significant. However, the disturbance caused by hunting at the roost is likely to have signficant impact, and may deter the birds from breeding or even using the site.

IMG_4444A sign of things to come? Several nest platforms have already been built. Breeding is unlikely to be successful if hunting at the site continues. Technically, since it is such a recent arrival in the country, Asian Openbill is not yet a protected species. Hopefully, this can be amended soon.

IMG_2605 IMG_2612When birds arrive, they quickly lose height with legs dangling vertically, when their appearance can be quite pelican-like. No wonder the locals call them burung undan (pelican). In Seberang Prai, the locals know it as burung seriap (Grey Heron). Allen’s latest edition names it Upih paruh sepit, which is a more or less literal translation.

IMG_2592 IMG_2579 IMG_2640Taking a good look at us!

I’ve been building up a map with details of sightings in Peninsular Malaysia this year. Click on the link and take a look! By clicking on the markers, you should be able to see site, date and number details.Here’s a quick screen grab which shows distribution only. If you’ve seen any in places which have not yet been marked, please get in touch!

AO mapThere’s also a Facebook page Tracking the Asian Openbill stork in Malaysia where you can add photos, report sightings and keep up to date with the invasion!


8 thoughts on “Tracking the Asian Openbill invasion

  1. Since its presence will most likely be quite frequent what would the bird status be in Peninsular Malaysia? Fairly Common?

    • I would put it as locally common. It is common in the northern paddy belt but does not appear to frequent the Bagan Serai paddyfields as much. Then it becomes commoner down south. No records from the East Coast paddyfields yet.

  2. i’m more than happy to join if someone invite me to the club, maybe i can cover besut setiu and kuala berang area – some paddy area to search for needle in haysack maybe

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