No bigger than a human thumb, the volcano hummingbird exists only here in the Talamancas.

She weighs barely as much as a penny and feeds in the shrubs on the tiny mountain flowers that suit her miniature bill.

But her appetite is anything but small.

She has to replenish 12,000 calories a day.

The flowers release only a small serving of nectar at a time to keep her coming back for more.

And she has to fight for every drop.

(birds chirping) The volcano hummingbird's ancestors moved up to these peaks to carve out territory above the more crowded lowland forests.

Now, she is custom-built for the austere environment.

For her tenacity, the mountain rewards her with her own little world of pint-sized flowers.

Her daily feeding and gardening keep the plants in fruit across the mountain peak.

And even feeds a few hardy neighbors.

A silky-flycatcher appreciates the fresh high-altitude produce.

(wings humming) During mating season, male volcano hummingbirds will ascend as high as 11,000 feet and perch in the open to attract females with their iridescent gorgets.

But after mating, he heads off to more comfortable climates, leaving the female to do the rigorous work of nesting above the clouds.