It returns to the place where it last left its chick
in the hope that it might still be close by.
But chicks tend to wander so, the adult has to call to it.
The chick responds and they slowly home in on one another.
The plaintive entreaties of the chick stimulate the adult
to regurgitate a mouthful of fish.
With the return of one parent, the other is free to go to sea to feed for itself.
Aware of the leopard seal's presence,
the penguins press together at the ice edge,
unwilling to be the first to risk diving in.
Occasionally, the seal comes out on to the ice and attempts to grab one.
But its most successful strategy by far is to lie in wait.
It hides behind a corner of ice.
The emperors gain confidence and make a dash for it.
The first wave of penguins escape.
Once in open water, they will be safe.
But the seal is alerted by the noise and through the mass of bubbles,
it makes its attack.
Almost invariably, it makes a kill.
Encouraged by the absence of the seal,
the remaining penguins make a break for the open sea.
In time, their chicks will fledge.
And when the Antarctic autumn is near its end,
these adults will walk across the newly-formed ice,
to endure yet another winter on the frozen sea.