Cormorant; a bit wet or a well evolved fisherman?

A cormorant apparently drying its wings is a common site along the Thames. However there is more behind this wings spread posture than is often thought. It was once commonly believed that cormorant feathers get wet because these birds are deficient in producing a water resistant oil from the preen gland. In fact research has shown that it is the microscopic structure of the feathers themselves which makes the birds feathers ‘wettable’. Rather than being a negative thing, this helps reduce the cormorant’s buoyancy, so they can dive deeper more easily when hunting for fish.

People often wonder why a bird that spends so much of its time in water bothers to dry its wings at all. The wings spread position is believed to help the birds warm up after a dip into cool water. The dark feathers absorb heat, particularly on a sunny day. Other theories include that the wings spread position helps the feathers realign themselves correctly after a swim, aids parasite removal and assists with balance when perched.

A lot more going on than a deficient oil gland!