Do Whales Get the Bends? by Tony Rice

Author:Tony Rice
Language: eng
Format: epub
ISBN: 9781408197943
Publisher: Bloomsbury Publishing
Published: 2019-12-06T00:00:00+00:00

Birds

54 Why do seabirds follow ships?

Probably for at least three different reasons: as a potential source of food; to hitch a lift; or simply out of what we would call curiosity.

The food source explanation probably has two origins. First, many inshore and shallow feeding birds, including gulls, terns, gannets and boobies, probably learn at an early age that fishing vessels are good sources of food as fish escape from the nets during hauling and the fishermen subsequently gut the fish and throw the trash overboard. In the birds’ minds any ship therefore probably represents a possible food bonanza. But all ships, and particularly big ones, also provide potential food as small crustaceans and fish lurking a few metres down are brought to the surface in the turbulent waters of the ship’s wake. Terns are often seen taking advantage of this phenomenon, fluttering over the wake just above the surface and apparently paddling along on their feet and occasionally dipping their bills into the water.

For many long distance gliders, such as boobies, gannets, frigate birds and, particularly, albatrosses and their tube-nose relatives (see Q55), ships in the middle of the ocean are welcome sources of heat and, as a result, rising air thermals that the gliding birds can exploit just as a human glider pilot does. Ocean going ships, including cruise ships, are from time to time surrounded by such birds, sometimes dozens of them, wheeling all around the vessel for hours or even days on end. And they can disappear just as suddenly as they arrived. Who can say whether their presence is because the ship happens to be going in roughly the same direction as the birds at the time, or is simply an expression of their curiosity and sense of fun?

But hitching a lift can mean exactly that, when distressed birds land on ships in a desperate last ditch effort to survive, usually during the day. These boarders are often not seabirds, but land birds exhausted by bad weather on their normal migration route or, more often, blown off course and out to sea. Probably the best thing you can do for these reluctant hitchhikers is to offer them some fresh water, something they have been unable to get while they have been over the sea. Sadly, however, they rarely survive the trauma they have experienced.

In contrast, night-time avian visitors often have a much better chance of survival. Many of them are true seabirds, like petrels and shearwaters. These are maritime professionals, quite capable of surviving at sea, but have landed on the ship because they have been disorientated in the darkness by the ships’ lights. Assuming they haven’t damaged themselves by crashing into a lamp or part of the ship’s superstructure, these birds have a good chance of survival and, after a bit of a rest, they often leave the ship and carry on with their lives.

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