CHAPTER 9
How Seabirds Catch Food
Some seabirds feed onshore in very obvious ways. Gulls gather at the
local tip, await the arrival of the garbage truck, and then squabble with
their fellows for the privilege of being the first to tear open a black
garbage sack to enjoy its unsavoury contents. Far to the south, a Giant
Petrel, once it has killed a Macaroni Penguin, does not delay before rip-
ping open the victim’s body cavity and thrusting its chunky bill into the
warm intestines. More appealingly, a graceful Common Tern flies paral-
lel to the beach before flicking itself in mid- air through a 180 degree
turn. It has spotted a tiny fish. It splashes into the water and emerges
triumphant, the prey twitching in its blood- red bill.
But modern research has shed light on the birds’ less obvious feeding
techniques. If frigatebirds are clad in plumage that is barely waterproof,
are they able to feed without getting wet? If a guillemot is bobbing on
the ocean far from land, and certainly spending the night at sea, can the
night be used for feeding as well as the day? When a penguin upends
and disappears underwater, how deep might it go? And, if it dives deep,
how does it cope with the physiological challenges? These are the sorts
of questions to which answers are now available.
Many species patrol the seas to catch their food at or very close to the
surface. However, a tropical few actually specialize on catching food in
mid-air. Prominent among this group are the frigatebirds. On many
tropical evenings I have watched frigatebirds hanging on angular wings,
sustained aloft by a breeze billowing up the cliff. Occasionally the bird’s
forked tail twitches to correct the bird’s position after it has been buf-
feted by turbulence. Then, the frigatebird spots a booby returning from
the sea. Instantly its languid demeanour vanishes. Thanks to deep down-
strokes the acceleration appears instantaneous and, within seconds, the
booby has trouble astern. The frigatebird grabs the victim’s tail while