Tuesday, February 26, 2013

The insatiable appetite of King Whale-head

The weirdness of the shoebill goes far, far beyond its taxonomy and evolution. Visually, they resemble something resurrected from the depths of prehistory. Despite its prominent bill and captivatingly unique appearance, the shoebill is a reserved animal; in fact, while many may find them ugly or comical, I think they have a certain stoic beauty about them. They are truly the wise, old fishermen of the bird world; standing motionless for hours on end, waiting for fish to come to the surface.
A shoebill in its preferred fishing spot: perched on floating vegetation. Photograph by Jnissa, from Flickr.
Most piscivorous (that is, fish-eating) birds display certain adaptations for hunting their prey, whether it be a lance-like bill, sharply-hooked talons, spacious pouches, or paddles. But the shoebill is, not surprisingly, an anomaly: its bill is stout and broad, rather than slender to pierce through water; their toes are unwebbed and they neither dive nor swim.

Shoebills fill a very specific niche: they prefer to hang out around poorly-oxygenated waters, areas in which fish such as catfish and lungfish often need to rise to the surface to gulp down air. They are not so much unequipped for fishing as they are extremely well-equipped for angling in different waters.

A shoebill ruins some poor fish's day. Photograph by Morgan Trimble.
Their fishing tactic is less like that of a spear-fisherman, and more like a catfish noodler: they don’t simply pluck fish from the water, they go all in. They simply wait for a fish to take a breath and then launch into the water in a flurry of splashing feathers, killing them with a nail-like projection on the end of the bill. The “hunt” usually consists of loss of balance and, in some cases, entanglement with foliage. Some individuals have had to free themselves from vegetation before they can even swallow their meal. The shoebill’s broad and powerful beak allows them to tackle a wide range of prey, ranging from snakes, turtles, and young crocodiles to rodents, young waterfowl, and, apparently, an antelope calf.

Did you catch that last one? I’ll say it again: it ate a baby antelope.

The business end of a shoebill. The nail-like projection on the tip of the bill can be seen clearly in this photo. Photograph by Makitani, from Flickr.
Yes, it’s true. There exists just one account of a shoebill feeding on a newborn black lechwe, a subspecies of wetland-dwelling antelope found throughout central and east Africa. I’m a little unsure what to make of this observation: the shoebill is certainly well-equipped to kill such prey, but it would be impossible for the bird to swallow, and it lacks the proper equipment with which to tear its prey apart. Perhaps the shoebill in question was observed feeding on a calf that had already died. No matter what the observation actually was, this is the only account of a shoebill feeding on prey of that size, and it was made in 1961. It is not typical shoebill behavior to chase around antelope. Lungfish are easy enough to catch.

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