There are two types of bats at Guestwick: Common Pipistrelles and Natterer’s. They roost high up in the rafters.
The Pipistrelles emerge first, flying around for a few minutes, before squeezing out through minute gaps around the church door.
The Natterer’s come out a little later, preferring to exit through small holes in the roof to get outside and find food.
Without the help of the specialist cameras, the bats are near impossible to spot, lost in the darkness.
About a third of the churches surveyed in the study had no idea that bats were living there.
But in others, their presence was much more noticeable. Bats can be messy houseguests.
“They’re lovely, but they’re problematic too,” says Graeme Peart from St Margaret’s Church, Saxlingham, just a few miles from Guestwick.
He’s responsible for the upkeep of the church – and says the bats started to become a nuisance about 15 years ago.
“There’s the urine, the droppings,” he says. “One time there was a carpet leading up to the altar that became absolutely sodden with urine and droppings and had to be thrown away. They also destroyed the brass work.”