Case Study | Bat Mitigation
Posted in:
Bats, Biodiversity, Protected Species
Date posted: 1 December 2019
A lot of AEL’s work involves making provision for bats affected by development. The legal protection afforded to all bat species (primarily the Habitats Regulations 2017, as amended) in the UK requires that mitigation (and/or compensation) must be provided in situations where bat roosts are disturbed, damaged or destroyed. Essentially, the law requires that there should be no net loss and that Favourable Conservation Status of local bat populations must be demonstrated. The mechanism for ensuring that bats and other European Protected Species are safeguarded is the wildlife licensing system administered by Natural England.
In 2016, AEL was commissioned to carry out surveys at a residential property in Chew Stoke, near Bristol. The initial inspection of the building revealed a number of potential roost features, including gaps between old timber cladding and missing, raised and slipped roof tiles. A small number of bat droppings was also found within the roof void. These were collected in sterile containers and sent to a laboratory at Warwick University for DNA analysis. The result came back as Brown Long-eared Bat Plecotus auritus.
Follow-up surveys proved that in fact three species were roosting in the house: Brown Long-eared Bat; Common Pipistrelle Pipistrellus pipistrellus; and Soprano Pipistrelle P. pygmaeus. A further six species were recorded in the grounds of the house, foraging and commuting: Leisler’s Bat Nyctalus Leisleri; Lesser Horseshoe Rhinolophus hipposideros; a Myotis species Myotis sp.; Nathusius’ Pipistrelle P. nathusii; Noctule N. noctula; and Serotine Eptesicus serotinus.
The short video below shows a Soprano Pipistrelle leaving its daytime roost at dusk. The bat emerges at 0:11.
Armed with the data collected from our surveys, plus information from a local biological records data search, an application was made to Natural England for a European Protected Species (EPS) Licence. Supporting documents submitted included a mitigation plan, method statement and schedule of works. The application was to destroy the existing roosts, which it was determined were of low conservation significance (none were considered to be maternity sites and only a low number of bats were using them). To mitigate for this loss, it was proposed that roost features (including roof tiles) should be dismantled by hand, supervised by bat Ecologist and at a time of year that would cause least disturbance to any bats present. Woodcrete bat boxes were erected in trees nearby to provide a temporary home for bats while the demolition and re-build took place. And, most importantly, the new building incorporated self contained bat roosting units behind the new wooden cladding. These were installed with a small opening at the front to allow bats to enter and leave.
Access point to bat roost shown above centre.
Before applying for a licence, it was necessary to get the mitigation strategy agreed by the Local Planning Authority. This is because LPAs have a legal duty to ensure that Natural England are likely to grant a Licence, before giving planning permission.
We are very confident that this mitigation for bats will prove to be successful. Monitoring surveys will be carried out during 2020 and we will be providing an update. So watch this space!
This project demonstrates that usually, bats can be accommodated in development projects relatively easily, at low cost and without allowing access to the ‘living’ area, which is often a concern that residents have. Bats and humans can co-exist 🙂
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