As part of her Wild Five series that's looking at UK animals in danger, Leah's been on a night-time hunt for bats in London.
"When most people think of bats they think of vampires and horror movies. For a long time they've had a bad reputation but I'm out to prove that it's totally undeserved.
Certain species like Bechstein's bat have nearly been wiped out.
There are 18 species in the UK, but over the last 100 years their numbers have dramatically decreased. You can find them in most places like the countryside and the city.
I met up with some bat detectives at Holland Park Ecology Centre in London to see if I can find some.
These mammals are nocturnal which means they do most of their hunting at night, so once it was dark it was time to set out.
Filming was at night because that's when bats do most of their hunting.
We headed for a pond because bats love hanging out near water where there's loads of insects. They can eat up to 3,000 bugs in just one evening.
Action is being taken to protect these animals. It's now illegal to kill or injure them or to destroy their roosts.
And experts say everyone can help by making their gardens more friendly for bats and the insects which they eat."