Wednesday, 23 December 2015

Photographic Advent Calendar, Day 22: Northern Gannet

The Gannet (Morus bassanus) is the northern hemisphere's answer for an Albatross, and with a wing span of almost 6 feet, they aren't far off the size of some of the smaller Diomedeids. Gliding and skimming over waves, or plunging into the sea from great heights like a black-and-white dart, the Gannet has to be our most familiar seabird after the Puffin. And they are almost quintessentially British: 60-70% of the World's population of Northern Gannets breed around the UK, mostly on Scottish offshore islands. There are, however, a couple of colonies on the other side of the Atlantic in Quebec and Newfoundland (Canada). The British population stands at around 300, 000 pairs, with individuals living as old as 37 years.

Perhaps their most famous ability is that of their amazing feeding technique: this involves a vertical dive (from as high as 50 metres) into the sea, accelerating to speeds of 100 mph before penetrating the water's surface and darting after their choice prey, which takes the form of pelagic shoal species like Mackerel and Anchovies. To enable them to perform this impressive aerobatic skill, they have a number of adaptions: several subcutaneous air sacs are present in various locations around their body, which act as cushioners during the dive; their sternum is very strong, providing internal organs with protection from the forces of impact; their lungs are also well developed, which is thought to further aid support under high pressure; and their wings are able to fold flush against the body to permit an incredibly streamlined shape.

Curiously, this smart bird used to go by the name of 'Spectacled Goose' (or Solan Goose), which referred to the bluish eyering that adult birds posses (see images below). To tell the different sexes apart, one has to get a decent look at their feet- yes, their feet! In males the lines running along the webbed surface of their toes is yellowish, compared to a more green colour in females.

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