Yellowstone has vast ancient lava fields. This porous volcanic rock holds on to very little water. It is dominated by lodgepole pine, a tree that can cope with the arid conditions.

 

The forest may be parched, but there is still water here, in lakes formed by ancient glaciers.

 

A visiting male otter woos a female on the lake's shore. But she seems a little distracted. Her two pups are nearby. They are about ten weeks old, and the time is right to lead them from the hold. Males are not above stealing food/ from cubs, so she makes it very clear that he is not going to be joining them.