In April 2021, Vincent Wildlife Trust commissioned the construction of our first bat tower, which was funded under the Green Recovery Challenge Fund. The idea behind the tower was to provide another summer roost for lesser horseshoe bats, which have been affected by the arrival of the bigger greater horseshoe bat in their original roost nearby. The majority of the lesser horseshoe colony had abandoned the roost, a derelict five-bedroom farmhouse that the Trust made safe for the bats in 2003 and established themselves in a garage on the neighbouring farm.

The garage was keeping the bats warm as there is a boiler running for the adjacent farmhouse. However, it was not a suitable roost in the long term due to the high light levels and disturbance associated with the use of the space.

The owners, Karl and Sandra, really love their bats and were happy for the tower to be built on their land. The chosen site is next to a hedgerow that connects the tower to the original roost and gives the bats shelter when they emerge.

Dr Henry Schofield, VWT’s former Head of Conservation, designed the tower based on his expertise and experience of similar constructions used  on the continent.

The 5m high bat tower consists of an insulated wooden frame, covered in feathered-edge timber boarding, and sits on a 1m high blockwork plinth. The tower footprint is only 9m², but still needed planning consent. The steep-pitch, pyramidal slated roof maximises the thermal gain from the sun to the benefit of the bats, whilst the bitumastic roofing felt underneath also helps to keep the bats warm.

Inside, the space is divided into three floors to provide a gradient of temperatures — colder on the ground floor and warmer at the top and includes temperature loggers to allow us to monitor the temperatures. The rough timbers and bitumen membrane allow the bats to perch throughout the building.

The bat entrance is fitted with a tip tray, a device that allows bats to fly through but closes the entrance if a predator attempts to enter.

The first evidence of bats using the tower was seen later that year, when it looked like some pipistrelles had found the new roost. In spring 2022, we removed the door temporarily to encourage the lessers to find the site. And they did! Some lesser horseshoe bats were present that summer although none were breeding.

Early in 2023, a new letterbox entrance was cut on the main door to provide a second access for the bats. Numbers went up from a handful to 35 lesser horseshoe bats using their new accommodation.

Patience eventually pays off and the lesser horseshoe bats have at last made the VWT tower their new safe home for raising their young. A total of 45 adult lesser horseshoe bats have been recorded and at least half of them have had pups for the first time! This is very promising and we expect numbers will continue to increase over the next years, as lesser horseshoe bats are known to be faithful to the place where they are born.

Now that we have evidence that lesser horseshoe bats breed in this tower, we can use the design as a prototype for future projects to provide suitable lesser horseshoe roosts near woodlands, encourage the species back to their former range, link up populations and provide suitable roosts where they aren’t available or are under threat.

Marina Bollo Palacios, Senior Bat Conservation Officer (currently on maternity leave)

This building project was originally funded by the Government’s Green Recovery Challenge Fund. The fund was developed by Defra and its Arm’s-Length Bodies. It was delivered by The National Lottery Heritage Fund in partnership with Natural England, the Environment Agency and Forestry Commission.

All photos: ©Daniel Hargreaves