where seabirds find food | 149might put them at risk as ice retreats in the face of global warming but,
at least in the short- term, the conclusion could be premature. The High
Arctic (80°N) archipelago of Franz Josef Land, well north of Russia, is
now virtually ice- free during the summer. The region’s Little Auks have
lost their sea- ice- associated prey. Fortunately the retreat of large coastal
glaciers has released large volumes of melt water, generating a combi-
nation of cold and osmotic shock that stuns the zooplankton in front
of the glaciers and, for now, creates a summer feast for Little Auks.^5
Whether this will persist is open to question.
Half a world away, other birds also use the ice edge. This might be
anticipated for Antarctic specialists such as Emperor and Adélie Pen-
guins. It is more surprising for the lower latitude King Penguins raising
their tubby chicks, downy and the colour of café- au- lait, through the
sub- Antarctic winter. Remarkably, satellite- tracked parent King Pen-
guins from Iles Crozet (46°S) head south at this season to gather food,
mostly lanternfish (also called myctophids), for the chicks. This journey
takes them about 1,600 km from the colony and as far as the marginal
ice skirting Antarctica, where lanternfish are most abundant.^6
Another unexpected ‘habitat’ exploited by feeding seabirds is the sea
above moraine banks, higgledy- piggledy piles of stones and boulders left
as underwater deposits by long- gone glaciers. An intriguing example of
this comes from South Georgia where moraine banks occur at depths
of 400– 500 m at the margins of the continental shelf, before the shelf
break and the drop to the abyss of the South Atlantic. The study subjects
were Black- browed Albatrosses from the Bird Island colony, studied by
the British Antarctic Survey for several decades.^7 Fitted during chick-
rearing with GPS- loggers and stomach temperature sensors to pinpoint
where food was swallowed, the birds took in most beakfuls above mo-
raines. Just how a pile, admittedly a very large pile, of underwater boul-
ders can lead to more krill and fish being available to albatrosses at the
sea surface is not obvious. But the fact that the Dogger Bank in the North
Sea and the Grand Banks off Newfoundland are also moraine banks fa-
voured by both fishers and seabirds suggests a profound and consistent
link between these banks and local oceanic productivity.
Surrounding the world’s continents are the continental shelves, geo-
logically part of the continental crust and covered by relatively shallow