12

Chiru,or Tibetan antelope,have arrived for the winter rut.

In the energy-sapping thin air

The males must try to control groups of females

by constantly rounding them up and corralling them.

But the chiru have an advantage.

Their red blood cell count is twice as high as ours

Sufficient to supply their muscles with oxygen even at this extreme altitude.

Nevertheless,it's hard work keeping his harem in check

And the male's life is about to get even harder.

Another male is gearing up to steal his females.

With their rapier-like horns

The males won't risk fighting unless they really have to.

But if neither backs down,conflict is inevitable.

Some of these fights end in death.

While the males fence, the females look on.

Injured and weakened by the battle,the loser will be an easy target

for the predators and scavengers that patrol the wilderness.

Out here there's little room for mistakes.