Stalking open-mouthed

The African Open-billed Stork (Anastomus lamelligerus) is a large handsome bird (up to 94cm tall) with glossy purplish-black plumage and a wicked-looking bill.

Open-billed stork

Its name comes from the fact that even when the tip of the bill is closed, the sides still gape open:

Open-billed stork, highly specialized for eating snails

I spent about 30 minutes photographing this one hunting in the weed-covered lagoon while I was lounging by the camp’s (weedless) plunge pool (it’s a tough life). The stork evidently wasn’t going after fast-moving prey like fish or frogs, because it rooted around vigorously in the same underwater spot for some time. When it finally had what it wanted, it raised its head and swallowed in one swift motion, never showing what it had caught. Finally, I got two lucky shots just before the food went down, because of technical malfunctions where the victims got stuck on the stork’s bill!  Turns out what it liked best were tiny fresh-water snails, just visible in the photo above. The next shot is a close-up of the second successful foray:

Open-billed stork, highly specialized for eating snails

The unusual bill is highly specialized for gripping the snail while extracting the meat. This description explains the rooting around that I saw.

“..it holds the snail against the ground, using its razor sharp bottom mandible to sever the muscle that connects the snail to its shell, vigorously shaking its head until the snail body is extracted and promptly swallowing; the whole process can take under 15 seconds.”

(http://www.biodiversityexplorer.org/birds/ciconiidae/anastomus_lamelligerus.htm)

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