Geoscience Reference
In-Depth Information
razorbill, black guillemot, Atlantic puffin, and dovekie—and the extinct great auk. With some scientific valid-
ity, these birds are known as the penguins of the north, since they effectively occupy the same ecological
niches as do penguins in the Antarctic. In fact, the term penguin was first applied to the extinct great auk, and
may have had a number of origins. In Welsh, penguin means white-head, which might be descriptive of the
white patches in front of the great auk's eyes. Or it might have derived from the Latin penguis, meaning fat or
grease— the species was rendered for its oil, and sometimes the bird itself was used as fuel. Or it might have
referred to its disproportionately small wings through a corruption of “pin-winged” or “pinioned.”
At three-quarters of a meter (3 feet) tall, it was by far the largest of the auks and the only one that was flight-
less. It was the combination of these two traits that probably led to its demise. The great auk's breeding colon-
ies appear to have been quite widespread throughout the North Atlantic, where the birds served as sources of
fresh meat, first for trans-Atlantic explorers and later for fishers. It was said that they could be herded aboard
ships on gangplanks. Wholesale slaughter of the bird and decimation of its eggs culminated in their extinction.
The last sighting of a pair of Great Auks was made in 1844 on Eldey Island, Iceland.
GREAT AUK
Unlike their southern counterparts and the great auk, the other alcids have not lost the ability to fly. The cap-
ability for flight and prolonged deep diving appear to be mutually limiting and only coexist in the case of
alcids weighing 1 kilogram (2 pounds) or less— which includes all of the surviving auk species. However,
both the penguins and the auks (which are unrelated) possess a remarkable proficiency at “flying” underwater,
an example of convergent evolution—similar adaptation to a similar environment.
The auk's wing has been modified so that it can be used both as an aerial and a water paddle. It is short, re-
ducing its resistance in the heavy medium of water and optimizing underwater propulsion. All the wing ele-
ments have been strengthened, by the enlargement of ligaments and thickening of connective tissue, to adapt to
the stresses of underwater diving. In addition, the pectoral muscles are exceptionally large, allowing the bird to
compress the breast feathers and thus reduce buoyancy when diving.
The larger the bird, the deeper it can dive. We can only speculate to what depth the great auk was able to
dive, but it probably exceeded 100 fathoms. Even its much smaller relatives plumb surprising depths; common
murres have been caught in fishing nets at 100 fathoms.
Seabirds have evolved a variety of feeding strategies to exploit all tro-phic levels of the food web and thus
avoid competition. Petrels, like the albatrosses to which they are related, wander the world's oceans, where
