PLANET EARTH Mountains

A male bear would kill and eat them given the chance. But big animals find it difficult to get about here. Males may be twice the size of a female and even she can have problems. Her cubs, however, make light of the snow and of life in general.



But the mother faces a dilemma: it's six months since she last fed and her milk is starting to run dry. She must soon leave the safety of these nursery slopes and lead her cubs away from the mountain. If she delays, the whole family will risk starvation.



Summer reveals the true nature of the Rockies. Stripped of snow, the peaks bear their sculpted forms. Only now can mountaineers reclaim the upper reaches. Two miles up the crumbling precipices（峭壁） seem devoid of life. But there are animals here - a grizzly bear. It seems to be an odd creature to find on these high rocky slopes. It's hard to imagine what could have attracted it here.



At this time of the year bears should be fattening up for the winter. Yet they gather in some numbers on these apparently barren slopes. They're searching for a rather unusual food - moths. Millions have flown up here to escape the heat of the lowlands and they're now roosting among the rocks.