C is for Cormorant

Cormorant (Phalocrocorax carbo)

This common seabird appears to be a relic from the time of the dinosaurs. Whether it’s standing upright on a rock showing it’s reptilian, curved neck and scale-like wing feathers or flying high and looking every bit like a pterosaur. It evens swims ‘nessie-style’ ,body submerged and head held high on its long neck. Everything the cormorant does seems weird. For a start it is definitely more at home in the water than in the air, yet unusually for a water bird it can perch quite happily in trees with its webbed feet.

Despite its appearance, the cormorant is not a particularly ‘primitive’ bird (though it used to be thought of as such). It belongs to the order Suliformes, which also includes the gannet Morus bassanus. The earliest modern bird groups are actually the galliformes or game birds (grouse, pheasants etc) and the anseriformes-ducks, geese and swans. In Britain, the similar shag (I know, I know!)  Phalacrocorax aristotelis is smaller, lacks the cormorant’s white throat patch and has a quiffe-style head crest. While we’re talking classification, the name ‘Cormorant’ actually comes from the latin ‘Corvus marinus’ meaning sea raven¹. Of course, it is not a corvid (from the crow family) at all, but it’s clear to see how this big, black bird got the name.

Cormorants are a familiar sight along rocky coasts and estuaries. Their presence in freshwater areas such as lakes, canals and large rivers such as the Thames and the Severn (Much to the distress of some freshwater anglers), is actually fairly recent . One angler who approached me whilst volunteering for the RSPB even thought that cormorants weren’t native!  They feed mainly on bottom-dwelling fish such as flounder and some shrimp which they chase down underwater and gruesomely swallow whole with a neck-stretching gulp. Shags, on the other hand feed on free-swimming fish, so the two species live alongside without competition (this is known as niche separation in ecology).

However, cormorants seem less fussy in fresh water, taking trout and other course fish, which has made them angler’s enemy number one.  Although they are a new predator on the block and should be considered when conserving endangered species such as salmon, it is unlikely they have a big impact on overall fish populations*. I’m going to stick my ill-informed neck out here and offer two opinions: 1-That cormorants are reducing fish numbers to natural, sustainable levels in otherwise overstocked fishing lakes and/or 2-That anglers are simply envious as they watch cormorants catch fish with ease whilst they wait in their chairs for hours.

The cormorant is well adapted for its semi-aquatic lifestyle, with wide webbed feet for propulsion, a streamlined body, a hooked beak for snagging slippery fish, and even eyeballs that can be ‘squeezed’ flat so it can see equally well under water as it can in air!

But-get this. The cormorant isn’t waterproof! This is where the cormorant’s distinctive wing-spreading pose comes from. They have to dry off their wings. Why would a swimming bird have plumage which gets soggy?
The answer is, whilst the structure of the cormorants feathers reduces waterproofing, it also helpfully reduces bouyancy so it can dive more easily².  The wing-spreading behaviour allows the cormorant to make this compromise.

So, to the sea raven. Fisher extraordinaire, the envy of humans and conqueror of all waters. Long may they spread their wings over our coasts and wetlands.

*Due to the basic principle that predators will not drive their prey numbers to unsustainable levels.

References

1- Fransesca Greenoak. (1981) All the Birds of the Air. Penguin.

2- Paul Ehrlich, David Dobkin, and Darryl Wheye. (1988). Spread wing postures. Available from: http://www.stanford.edu/group/stanfordbirds/text/essays/Spread-Wing_Postures.html