introdUction to the world’s seabirds | 3hope is that the westerlies will have blown rare seabirds from further
west in the Atlantic towards the Irish coast. These might include Great
Shearwaters whose breeding home is the Tristan da Cunha group of is-
lands of the South Atlantic. But the shearwaters passing Ireland are only
a minority of the millions heading south at this season. What is the nor-
mal route of the shearwaters when they head north from their breeding
grounds to spend the northern summer in the North Atlantic and then
return south in September? Do they follow the same route north- and
southbound, or do their travels take them on some sort of circular loop,
the better to exploit prevailing winds? Do they travel continuously when
migrating, or stop off for a week or more at oceanic ‘oases’ where the
pickings are particularly good?
Forward a few months to the month of January, to the grey waters off
Newfoundland where many Great Shearwaters passed by in late sum-
mer. The weather is grim, the nights long. Yet this is a part of the world
chosen by many seabirds from Greenland, for example Brünnich’s Guil-
lemots, to spend the winter. To catch food, the guillemots dive many
metres below the surface. Even in the middle of a winter’s day, light
levels and hence visibility will be poor at the depths where guillemots
catch food. What allows them to succeed, as assuredly they do, and do
they feed at night, when the difficulties are presumably still greater?
If guillemots face daunting dives, spare a thought for Emperor Pen-
guins. Once a female has laid and left the male to incubate the egg
through the darkness, the blizzards, the numbing – 40°C chill of the Ant-
arctic winter, she heads north to seek food in open water. But available
light will be very limited, especially at depth and even more so if she
dives under floating ice. Catching fish would certainly be easier if the
fish (rashly) signalled their presence by flashing lights.
Further north in the Southern Ocean, the westerlies are roaring
through the stormy latitudes of the forties and fifties. This is the domain
of albatrosses. If there is no wind, they sit becalmed on the water. Flap-
ping is not their forte. But let the wind blow. Let the albatrosses spread
their wings and lock them open using a special skeletal mechanism.
Then the birds, be they the smaller mollymawks, or the giant Wander-
ing and Royal Albatrosses with a 3.5 m wingspan, can glide. A wind of
50 knots is no buffeting enemy; it is a source of free energy. It helps the