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On the remote, rocky islands of the North Pacific,
you might find a happy-looking little bird.
Called the crested auklet, it looks
kind of like a cross between
a penguin and a quail.
They live in big, dense, noisy colonies
and go out to the ocean to feed.
They also, apparently, smell like tangerines.
The smell, which has been described as
“distinctive” and “pungent”, emerges
at the beginning of the breeding season.
As for what’s actually causing it,
the smell seems to come from a mix of
compounds secreted by a patch of special,
hair-like, possibly hollow feathers called
wick feathers found on a particular area
of skin on their back.
They just got a little tangerine patch back there.
The mix of compounds is dominated by aldehydes,
a kind of chemical that contains a
carbon bonded to a hydrogen and
double-bonded to an oxygen.
As for why, there are two hypotheses.
One is that the smelly aldehydes might be
a way for the birds to repel parasites like lice
— kind of like a built-in can of bug spray.
Experiments have shown that some of
the compounds in the smell can repel
or paralyze ticks or lice.
The other idea is that it might be
some kind of sexual display or some
other sort of social signal.
During courtship, crested auklets approach
potential mates and bury their bill in
that patch in what’s known as a “ruff-sniff”.
And they can definitely smell it.
Studies have shown the birds can tell
the scent apart from other smells and even
appeared to be attracted to it when
presented with a smelly fake bird.
Which is kind of neat, because for a
long time many experts thought birds
couldn’t really smell things.
That idea was debunked by scientists
in the 1960’s, and that research doesn’t
have much of anything to do with crested auklets,
but as a myth it’s had surprising staying power.
It might seem kind of funny,
but choosing the smelliest mate
might have some benefits.
If the scent is a parasite repellent,
for example, a smelly mate is less likely
to pass infestations to their mate or offspring.
The smell might also be an indicator
of how healthy the animal is in general.
Its body has to produce those smelly chemicals,
which requires energy.
And because all smells eventually fade over time,
an animal that depends on cologne to win a mate
has to keep making new compounds all the time.
Which means it has the energy to burn
to make smelly molecules, even though
those resources could be used for other,
more survival-oriented things.
This means for crested auklets, a strong scent
might be a way to show that you’re not only healthy,
but you have the resources to burn.
Citrus-scented birds are pretty neat,
but they’re far from the only
fascinating animals out there.
If you want to learn about more of them,
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