Emperor penguins in a huddle during a snow-storm.
Normally penguins are very territorial and will not approach each
other easily, but this behaviour is one of the ways that emperor
penguins manage to survive successfully in the depths of the
Antarctic winter. Scientific measurements and calculations have
shown that by huddling together, emperor penguins use about half the
energy that they would otherwise and would starve to death over the
winter rather than come through and raise chicks as well.
There is a constant changing of position from the
outside to the inside and during a snow storm lasting days, the
whole huddle will slowly move a couple of hundred meters or more.