Asian Openbill

Some years ago, I was in Jahangirnagar University early one morning for birdwatching. The campus was enveloped in dense winter fog. I stopped at one of the lakes where I could hear the racket of whistling ducks but visibility was poor. As the fog slowly lifted, some trees beyond the lake gradually came into view. On the high branches of one of the trees was a group of black and white birds. The fog, the stark denuded branches of the trees, and the large, gangly birds made a primeval scene. At first I thought the birds were lesser adjutant storks (modontak) but then I noticed the distinctive gap between the top and bottom parts of their bills. These were asian openbills (anastomus oscitans), known as shamukkhol in Bangla.

Since then, I have run into openbills many times. They are about 80 cm tall, and can weigh as much as 1.5 kilograms. Among the five types of storks in Bangladesh, this is the only one found in abundance and year-round. Globally they thrive over a large range from western India through Bangladesh all the way to Vietnam.

The long-legged bird, coloured black, grey and white, is usually seen in small flocks near water: shallow lakes, marshes and paddy fields. It roosts and breeds in large colonies and builds its nests at high tree branches. The openbill forages in shallow water by probing the ground with its bill looking for molluscs and small marine animals.

To me, the most interesting aspect of openbills is their bill. Since they live primarily on snails, it was long thought that this gap enabled them to crush snails with their bill like a nutcracker. Considerable research was done to verify this. But it turns out that this gap is nonexistent in juvenile openbills and grows with age. Yet juveniles are also able to eat snails.

In fact, the openbill uses a different technique to eat snails. After crushing the snail with the tough bill, it holds it in place with the lower mandible while severing the body of the snail from its shell using using its sharper upper mandible.

So its gap seems mysterious. However, the snail-eating habit endears the bird to farmers in Southeast Asian nations where it devours large numbers of apple snails. These snails are pests that damage crops.

Openbills are usually quiet, but during breeding season they make a clattering sound with their bill while courting a mate. The plumage of males and females is normally identical, but during breeding, the male plumage turns predominantly white.

Where can you find them? Besides Jahangirnagar University, I have seen them in several other places. On the road to Sylhet, just before reaching Bhairab, there is a large bridge. During winter I have seen openbill flocks on the banks of the river underneath. Once I saw a flock of hundreds high in the sky over Hail Haor, flying to destinations unknown. They can also be seen at the other haors and near water all year round.

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