Dense forests are distributed in the southern and middle sections of Qilian Mountain in Northwest China. Its northern part, however, is a plateau desert. The ecology here is fragile, but it has become home to blue sheep.

The fights between rams usually turn fierce after the winter solstice. They have to use up all the strength they have accumulated for a year before they can win the right to mate.

Ewes are forced to leave the group and hide on steep cliffs to escape the endless harassment. But rams have the same superb climbing ability -- as long as there is a place to stand, they can steadily climb up and catch up with the ewes.

The chaotic mating period comes to an end after about a week or so. They also need to avoid snow leopards and save their energy to survive the long winter.