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The
Manx Shearwater is a member of the Procellariiformes, the order of birds which
includes the albatrosses, the Fulmar and the storm-petrels.
It is beautifully
adapted to leaving at sea, with long, narrow wings, and its feet placed far back
on its body for efficient swimming.
Unfortunately this makes life on land difficult; it cannot walk properly, but
shuffles along on its belly, making it easy prey for predators such as gulls.
Unfortunately this makes life on land difficult; it cannot walk properly, but
shuffles along on its belly, making it easy prey for predators such as gulls.
In
order to minimize this danger, Manx
Shearwaters nest in burrows and only come
to, or leave, in the dark. Manx Shearwaters are extremely noisy at their colonies
after dark, the darker the night, the more tumultuous the sound, as birds fly
in
whilst others emerge from the burrows.
Once they have
reached breeding age, Manx Shearwaters return in March, when they clean out
their burrows and find their mates, most choosing the same partner as the year
before. After mating, the female leaves the island for about a fortnight to form
the single, large egg, 15% of her body weight.
She returns to
the Bay of Biscay which she passed through on her northwards migration, back
from South America, where she can feed on the plentiful stocks of sardines. The
male, meanwhile, stays nearby, visiting the burrow each night, perhaps to ensure
that no one else takes it over.
When the female
returns, usually by the middle of May she lays the egg and departs again to
feed, leaving the male to take the first incubation stint. Thereafter the pair
take it in turns to incubate the egg, each doing so from four to eight days at
a
time while the other goes off to feed.
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