A long-term project to relocate bats on the Graven Hill development has been hailed as a success as several endangered bat species have taken over newly installed roosts in the form of bat boxes.
Back in 2015, when plans were developed for a new 1900+-strong village community, the Graven Hill Village Development Company (GHVDC) was formed to oversee the development of the abandoned 188-hectare former MoD site at Bicester.
GHVDC appointed specialist ecologists at Waterman Infrastructure & Environment, and the abandoned buildings, hangars and woodlands were all carefully surveyed for any signs of bats roosting, breeding, feeding or using habitats as commuter routes to other grounds.
Evidence including active bat roosts were found for ten species, including the Common Pipistrelle and the Brown Long-Eared Bat. There are presently 17 species of bats native to the UK, and over half of these species are found on site.
As a legally protected species, Waterman I&E had to apply Natural England for European Protected Species mitigation licences to demolish any affected buildings or sites and detail what mitigation and enhancement measures would be introduced to further protect the bat colonies.
Simon Dowell, Principal Ecologist at Waterman, explained: “As part of the licence granted by Natural England, we had to provide alternative roosting options for the local bat populations, and so bat boxes have been provided as part of a long-term ecology project to support the bats at Graven Hill.
“We’re now delighted to have discovered that several of the boxes we put up in the last couple of years have been colonised by the bats. Most bats are crevice-dwelling, so they like trees and buildings with rough interiors and edges to hang onto.
“Our bat boxes range in size. A hibernation box might be 50cm high by 38cm wide and that can hold hundreds of bats, a smaller one of maybe 36cm by 16cm can potentially hold 50-100.
“Ours are made out of woodcrete which has a rough surface they can hang on to, but we also include wooden baffles which they hold onto and they are also designed to stop drafts getting in.”
Some bat boxes are naturally damaged or lost in bad weather, but can be attached to almost anything. Some are round to mimic trees and are placed deliberately at different heights and directions so the bats can choose their own “des res”. Bats are also transitional and might, for example, relocate if one box gets too hot.
Waterman Infrastructure & Environment has static bat detectors placed at Graven Hill to pick up the calls and echo locations of bats in situ. Exact numbers are hard to define due to the bats’ nocturnal and roosting habits, but signs are it is a substantial presence.
Said Simon: “It is great news that the bats have taken to their new roosts and we want to make sure they continue to thrive at Graven Hill. The bats originally were mostly using the old MoD buildings rather than woodland on site to roost, but they have now found the boxes in the trees and seem to really like those.”
“Graven Hill Residents may well see the bats come out to feed at dusk but the bat boxes have been deliberately sited away from residential areas so they won’t be disturbed. We will also be providing a plan for new roosts but, again, these will be well away from any future developments so the bats can continue to enjoy their new homes at Graven Hill.” added Simon.