Life and survival in the colony.

In the challenging conditions of
Antarctica, life in a colony offers
many survival advantages for
penguins. First, safety in numbers.
With multiple eyes and ears alert
for danger, the colony is quick to rumble
predators such as lurking leopard seals
and scavenging giant petrels. By sticking
together, individuals are less vulnerable
to attack. On land, Adélie penguins will
join ranks to chase away predators; when
fishing, they enter the water in groups,
swimming close to one another, and all
return to the safety of land – or ice
floe – at roughly the same time.

For emperor penguins, colonies also
provide protection from the elements.
When freezing Antarctic winds whip
across the ice, the birds form a tight
huddle, called the turtle formation, in
which each individual leans into its
neighbour for warmth and shelter.
Vulnerable juveniles remain at
the centre. The others move in a
continuous slow-motion rotation,
those on the windward side shuffling
around the edge of the group to
the leeward side where the wind
is less fierce. By cooperating as a
group in this way, every individual
increases their chance of survival.

Penguin colonies aren’t hierarchical –
there are no alpha individuals in charge.
During the breeding season, however,
males and females must pair up.

Getting the message across

To find a mate, a male emperor will
wander around the colony, stopping at
regular intervals to utter his ‘ecstatic’
courtship call: he’ll let his head fall to his
chest, inhale, point his bill to the sky and
call for one or two seconds, then continue
walking. Once a female shows interest,
the two peel off from the crowd and
perform a choreographed face-to-face ritual in which they mirror
each other’s movements for
several minutes until the bond
is forged.

They then waddle
around the colony together.
In a crowded, noisy
colony, established
penguin partners can
recognise each other
by their unique calls. In emperor
penguins, vocalising
is particularly
important, as pairs
don’t build a nest
so have no fixed location at which to meet.

This species
has evolved the widest variation in calls
of any penguin, with a unique ability to
use two frequency bands at the same
time. This not only allows adults to locate
a partner by their distinctive individual
voice, wherever they happen to be, but
also helps parents to locate their offspring
– and vice versa.

Adélie penguins use a range of calls
and moves in their courtship, too, and will
also deploy props to help strengthen their
pair bonds. This species makes a nest of
pebbles, which a pair gathers laboriously
at the start of the breeding season. When
a male is about to head out fishing, he’ll
often bring back a few more pebbles to
offer the sitting female. This proves to
her that he’s a reliable and hard-working
partner – one worth sticking with.

Watch your back!

Of course, the flipside of cooperation in a
colony is competition.

Resources are often
in short supply and each breeding pair will
do all it can to increase its own chances
of success. To this end, Adélie penguins
may steal pebbles from their neighbours’
nests to fortify their own, thus saving the energy they’d otherwise expend on
long pebble-collecting expeditions. When
pebble thieves are caught in the act,
they get a hard time from birds on all the
neighbouring nests. Nests nearer the edge of a colony – where thieves
are more likely to get away
with their crime – are thus
the ones most vulnerable
to attack. And those left
with fewer stones are
less likely to experience
breeding success.

Emperor penguins
sometimes take theft to
another level. Females
that have failed to breed
or have lost their own
chick may attempt to
steal another pair’s
chick. If a chick becomes
separated from its real
parents, it may even
find itself pursued by a
gaggle of such females
attempting to ‘adopt’ it as their own.

This bizarre kidnapping behaviour is thought to arise from this species’ unusually high levels of the ‘parenting’ hormone prolactin, which is what drives females to return to their chick after a long period at sea. For a kidnapped chick, things seldom end well: the adoptive parent soon loses interest, and, separated from its own parents, the youngster is left to starve. Thankfully, emperor penguins are very protective parents and a pair will defend their chick vigorously against any would-be kidnappers.