Tuesday, March 31, 2015

The Great Auk

Part Three

The Greak Auk was flightless.  It was very awkward on land, walking in an upright manner and straight ahead.  It did not seem to be able to change its path sideways.  It was ‘stupid and tame’ according to the early explorers.  All these traits made it vulnerable to exploitation.  

As seen in the attached photos, it was a striking bird with the basic black on the back and white on the breast of many species of sea birds.  In alternate plumage it sported large white ellipses above and in front of the eyes.  In summer its dark plumage was actually a dark brown in places with narrow white tips on the secondary wing feathers.  The throat and chin were dark. The bill was large (11 cm long/4.3 in) and had 6 to 12 vertical grooves on both mandibles, with more on the upper mandible.  This was a large, laterally compressed beak which it used as a ‘formidable dagger’ to those who were trying to capture it.  It slashed at would-be captors with great skill.  The Great Auk’s eyes were a dark chestnut brown and the mouth lining was a bright orange-yellow.  In basic plumage the white patches in front of the eyes changed to a white line and the dark throat became white.  It weighed 4-5 Kg (11 lb.), was 75-85 cm long (30-33 in.) with males being larger than females.  The wings were only 15 cm long (6 in.)  The feet were large, webbed and powerful.  

The birds nested on rocky islands well away from the mainland (and predators).  Because they were flightless they needed terrain where they could swim or propel themselves out of the water onto fairly shallow rocks where they could then walk above the tide line to suitable nesting sites.  This made only some islands useful for breeding where they nested in large, dense colonies.  A single egg was laid on bare rock and it is believed both adults shared the incubation, done in a standing position.  Incubation took about 6 weeks and the young left the nest at about 2-3 weeks of age.  We have many reports of their swimming while carrying their young on their backs.  Presumably they did not return to the nest after fledging and the young were carried, fed and protected for the rest of the summer.

The egg was a pale buff-olive colour with variable brown and black mottling and spotting.  It was about 12 cm (4.5 in) long and more elongated in shape than a hen’s egg with a pointed end.  Their diet was mainly fish but they also ate crustaceans.  They fed on menhaden, shad, capelin, stickleback and striped bass.  Off Greenland they fed on sculpins and lumpsuckers.  

Great Auk Egg (top centre) with Razorbill and Guillemot Eggs

This amazing species was a terrific swimmer.  Its body was well insulated with fat stores and it was streamlined for effective swimming.  On its migration it swam up to 60 Km/35 miles a day, moving from breeding grounds (which were sometimes as far away as Iceland) to Cape Cod.  It would dive to great depths and remain under water for at least 15 minutes.  It was such a good swimmer few marine predators could catch it.  It had a large gape and swallowed its prey whole.  It used its wings underwater to propel and steer its path.  When migrating they swam in great flotillas.  It swam with its head up and its neck pulled in and back.  When trouble appeared on the surface, they submerged and swam great distances under water.  

No comments:

Post a Comment