A study of the UK's largest rare bat that will last for the next three years gets under way this week.
There are thought to be 4,000 Greater Horseshoe bats in the UK
The research into the greater horseshoe bat begins at Purbeck, Dorset, and will look at roosts, flight patterns, diets, and the effects of farming practices.
A PhD student from Bristol University will tag the bats and use radio receivers to record flight patterns.
It is thought there are 4,000 greater horseshoe bats in the UK, with 200 breeding females in Dorset.
The project will be monitoring the annual bat swarming, a phenomenon which takes place every autumn.
It will seek to discover why bats return to their winter roosts to swarm.
Several groups, including the National Trust and Dorset Wildlife Trust, have recently restored some of the disused quarries on Purbeck and part of the study will focus on the bats' use of these abandoned quarries.
The project also involves all the main landowners on Purbeck, including private landowners.
Jon Flanders, a PhD student and main researcher for the project, said: "We are already beginning to build up a picture of where the bats are feeding and what routes they are using.
"Through the research, we have also discovered how one of our roosts holds double the number of greater horsehoe bats we had recorded there before, making it an even more important roost than we previously thought."