http://news.bbc.co.uk/2/hi/science/nature/3961069.stm
Friday, 29 October, 2004, 23:02 GMT 00:02 UK
'Smelly' mates guide seabirds
Seabirds called prions, which mate for life, find their nests by
sniffing out their smelly partners, scientists say.
The birds make their nests in deep burrows, which are very dark, so
they cannot rely on any other sense to find them, Science magazine
reports.
The birds also actively avoid their own smell, which could be a way of
making sure they do not breed with their kin.
Although this use of smell has been observed in mammals, it has never
before been seen in birds.
Tube-nosed
Antarctic prions, Pachiptila desolata , are so-called tube-nosed
seabirds.
They are strictly monogamous, although they rarely get to spend any
time with their partners. Instead they take it in turns to incubate
eggs and find food.
"All the shared life of the birds is inside the burrow because they
don't stay together at sea - they just alternate on eggs," said
co-author Francesco Bonadonna, of CNRS in Montpellier, France.
Sometimes a prion will forage at sea for up to two weeks, before
returning to the nest to begin a stint of incubation duty.
When they fly in from sea, they have to reliably find their own nest
among a medley of other nests.
But sight is not much use because they tend to come home at night and
their nests are submerged in deep burrows.
"Their burrows are underground and really, really dark," said Dr
Bonadonna. "They have nothing other than odour to find their way."
Inbreeding
Luckily, prions are rather smelly, so returning birds can locate their
nests by following their partner's distinctive smell.
"We found that the birds are able to recognise their partner's odour,
and we think they use this odour to recognise their burrows," said Dr
Bonadonna.
Not only are the prions attracted by their mate's smell, but they
actively avoid their own.
At first the researchers were surprised by this, because they assumed
that following its own scent might also lead it to its burrow.
But since the birds spend such a long time at sea their nests are
unlikely to smell of them, the team concluded.
But why the avoidance? Dr Bonadonna thinks it is a strategy to prevent
inbreeding.
He said: "To avoid mating with a bird that smells too similar is to
avoid mating with a bird that is related."
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