Surveys are being carried out at a church as part of a £4.975m pilot project to reduce the damage caused by bats.
An estimated 400 to 700 bats live in the eaves of All Saints Church, in Rutland, and their faeces and urine are damaging the building.
As a result the 14th century All Saints is one of three churches selected nationally for the pilot Bats in Churches scheme.
There are Soprano Pippistrelles, Common Pippistrelle and long eared bats, it is unknown if they are grey or brown ones, at the Braunston site.
Surveys have been carried out into the bats behaviour at the Grade I Listed site at dusk and dawn in June and July with a third coming later this month.
The scheme hopes to help the bats and the churches co-exist better together.
Rob Anderson, a church warden at All Saints, said: “There have been bats here for 200-years.
“Then an old chimney in the village fell down around 2014 and the bats that lived there moved into the church too.
“There are around 400 normally but the number of bats rises to 700 when they have babies.
“The problem is that their faeces drops through holes into the church and we have to clean it up regularly.
“We have 14th century murals in the church and the bats’ urine is staining them.
“Sometimes the bats fly inside the church.
“We have been looking for possible solutions but bats are protected and we don’t want to get rid of them.”
A multi-agency team made up of Natural England, the Church of England, the Bat Conservation Trust, The Churches Conversation Trust and Historic England is behind the project.
It has received £3.8m in support from the Heritage Lottery Fund plus additional funding.
The surveys are to monitor bat activity with a view to coming up with possible solutions to stop the bats damaging the church.
It is hoped to roll out the solutions into the churches next year.
Crispin Truman, chief executive of The Churches Conservation Trust, said: “The relationship between bats and churches has not always been harmonious so we are delighted to be a part of this project which celebrates both.
“It will enable us to better protect churches and their inhabitants, as well as supporting the communities who care for historic churches so that both can thrive.”
The other two churches in the project are Holy Trinity Church, in Tattershall, Lincolnshire, and All Saints Church, Swanton Morley, Norfolk.
The project’s findings are to be released on Wednesday, October 4, in Stanford-on-Avon, in Northamptonshire.