A project to bring back water voles to an area of Scotland where they hadn't been seen for 30 years is doing really well.
The number of water voles in the Trossachs had gone down because of the loss of their natural habitat and being hunted by American mink.
In fact the water vole is Britain's fastest declining mammal. Their population has gone down by more than 90% since the 1950s.
So three years ago some water voles were let loose in the forest area - and experts are really pleased with how they've settled in to their new home.
Since the start of the project 1,000 water voles have been released - and the last few were let loose on Friday.
It's the first place in Scotland to reintroduce water voles - and it's hoped other similar projects will follow.