- Transylvania is a wonderland for bats.

26 different kinds make their homes here.

And this is one of the most successful - the greater mouse-eared bat.

Come summertime, they often search out church towers, spending the daylight hours gathered in tight bundles for companionship.

But as dusk falls across Transylvania, the bats start to come alive.

It's time to go hunting.

One of the largest bats in Europe - greater mouse-eared - are ferocious predators.

And Transylvania's wild woods and meadows are still full of prey.

Unlike many, these bats don't use sonar to locate their prey.

Instead, their ears are hypersensitive to any tiny sounds from insects on the move.

Once these huge ears lock on, their unfortunate prey has little chance.

But keep very still, and you might just survive to see another night in the forest.

While churches make handy summer shelters, caves are critical sanctuaries for Transylvania's bats.

And Romania is riddled with caves, more than 12,000 in all.

In winter, they're the perfect hibernation hideaways.