WHY HAVE A BIG POUCH

Pelicans catch fish by scooping them up either at the surface or by diving for them. As much as 3 gallons of water (11.4 liters) can get scooped up along with the fish, hence the need for a large expandable pouch on a long beak. The weight of the water is far greater than the weight of the bird. It has to drain almost all the water away which takes a bit of time before being able to fly or attempt to swallow the fish. Sometimes other pelicans, indeed other sea birds will attempt to steal some of the fish before they have been swallowed.

Awkward as a pouched bill may look, it is a successful fish catching design that has existed unchanged among pelicans for more than 30 million years. It evolved quite independently among the pterosaurs, flying reptiles that flew above the fish laden seas for almost 200 million years long before the appearance of pelicans.
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