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Bats in churches: midnight en masse

Claire Boothby, Training and Survey Officer for Bats in Churches, explains why churches are vital habitats for bats and why the belfry isn't their favourite place!

December 2020

Six hundred soprano pipistrelle bats swoop and swirl around a grand medieval church before slipping through a small gap above a heavy gothic door and finding their way out into the countryside.

It is a sight to behold! This isn’t however an unusual sight in Holy Trinity Collegiate Church in Tattershall, Lincolnshire. In addition to pipistrelles, a maternity colony of approximately two hundred Daubenton’s bats have been using the church for decades.

Of course, Tattershall isn’t alone. While we’ve all heard of bats in the belfry, we don’t tend to think about the value of churches for wildlife. We might consider the value of churchyards, but rarely the interior of the building.

Two years ago, I started work on the Bats in Churches Project. While I’d enjoyed carrying out bat surveys before this, I hadn’t realised just how important churches are for our British bat species or appreciated the extent of the challenges posed for those caring for these historic and cherished buildings.

Why do bats roost in churches?

Churches give a range of conditions to support bats throughout the year. Sometimes places of worship can support hundreds of bats, and often multiple bat species will be found using a single church. Cracks and crevices in the supporting timber frame, roof and eave voids, and roofing tiles can all be ideal roosting sites. Contrary to popular belief, the belfries tend to be a bit noisy and draughty, so they’re not the best suited areas of a church for these winged mammals.

Some bats are crevice dwellers, whereas others like space to fly into their roost, or space to fly and warm up before leaving in the evening to catch their insect dinner. Essentially, they are big, complex buildings and often provide for the different needs that bats have.

Around this time, it’s too cold for foraging so bats are tucked up in their hibernation roosts. These tend to be found in cooler, more humid areas than maternity roosts, like church crypts. There is still a good deal of mystery surrounding hibernation, we aren’t even sure where our most common bats, pipistrelles, go over winter as the small number of hibernation roosts that have been discovered can’t possibly account for their population size.

Over half of the UK’s 17 breeding bat species are known to use churches and more have been found in these sites infrequently. Our volunteer surveys are helping us to discover more all of the time. We've even recorded one of the rarest mammals in Britain, the grey long-eared bat, in a church in Devon, and only a small number of roosting sites are known. This is only the second record of a grey long-eared bat in British church that I know of.

Cue Bats in Churches

The Bats in Churches project, funded by the National Lottery Heritage Fund, started in December 2019 and is working closely with over 100 churches with known bat roosts. When bats roost in small numbers they often go unnoticed, but when they roost in large numbers, their urine and droppings can amount to an unsustainable cleaning burden for church volunteers and can damage the priceless heritage that our historic churches house. This is why, we’re working with ecologists, church architects and communities to devise and trial novel ways for bats to continue to live within churches without causing damage or stress to the churches that host them.

This is a fantastic start, but we also need a better overall picture of how bats are using churches and attitudes towards them if we are to successfully conserve bats and the buildings they rely on.

We would like an accurate estimate of how many churches are used by bats and the geographical spread, and why some churches are used by bats and not others. We have some ideas, but a lack of evidence to support our theories. More information will help bat conservation and also help us to develop guidance for those caring for places of worship.

To answer these questions and many more, we’re running the Bats in Churches Study every summer. Anyone can take part, from those who have surveyed bats for years, to those just starting out. We’re asking volunteers to explore their local church for evidence of bats. You can find out more about what to look for and getting involved next year here.

Claire Boothby is the Training and Survey Officer for Bats in Churches

Follow: @BatsinChurches

The opinions expressed in this blog are the author's and not necessarily those of the wider Link membership.