Filmed in near darkness using a night vision camera,
the troop clambers along familiar ledges worn smooth by generations before them.
During cold winter weather,
the monkeys venture
deeper underground where the air stays comparatively warm.
At last, journey's end.
A cosy niche beyond the reach of even the most enterprising predator.
But it's not just monkeys that find shelter in caves.
These children are off to school.
In rural China
that may mean a long trek each morning,
passing through a cave or two on the way.