Cormorant

19 January 2020 | Posted in Charlotte Owen , Birds
Cormorant
Cormorant © Sean Stones

By Charlotte Owen

WildCall Officer

It’s nice to know what you’re looking at when you’re watching wildlife but one of the biggest challenges can be getting a good enough view for a definite ID.  Whether squinting at a distant speck as it disappears over the horizon or being startled by a sudden close encounter, we’re easily muddled by moving objects, baffled by obscuring branches or stymied by the silhouettes cast by low winter sun.  At times like these, a range of other clues can come in handy.  Birds often give themselves away by singing or calling, and some can be identified by their distinctive behaviour, posture or flying style.

The Cormorant provides an excellent example. This large, black waterbird strikes a signature pose so distinctive it’s the only clue you need.  Often choosing an elevated perch but making use of whatever scenery is at hand, the cormorant stands to attention with its body upright and wings stretched wide.  It will stay like this for several minutes at a time, barely moving, as it waits for its wings to dry off after a dive. 

Cormorants are supremely skilled at catching fish and will dive to depths of six metres or more in pursuit of their prey, staying submerged for a good 30 seconds before coming up for air.  To be able to do this, they have had to overcome their natural buoyancy so that they don’t just bob back to the surface every time they try to dive.  Some say that Cormorants will swallow pebbles to help them sink but their main adaptation is specialised feathers, which have a unique microscopic structure so that they don’t trap as much insulating air.  This allows them to dive freely but it also means that their feathers are not fully waterproof, so they do get soggy after prolonged swimming – hence the wing-drying pose.  But rather than rely entirely on the slow process of evaporation to dry themselves out, the same specialised feather structure provides a sophisticated self-drying mechanism that effectively ejects the bulk of the water as the bird surfaces.  After a few minutes to air dry, their plumage is primed and ready for another deep dive.

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