26 November 2025

Our ecology experts are delighted with the findings of this year’s bat box monitoring at the Graven Hill development in Bicester. The mitigation and enhancement measures implemented are proving highly successful, supporting a flourishing bat population on site.

Graven Hill, a 187-hectare former Ministry of Defence (MOD) site in Oxfordshire, is being transformed into a phased residential development, and our specialists have been providing ecological advice for over a decade. In 2021, surveys carried out by our licenced ecologist Simon Dowell (MCIEEM) identified ten day-roosts for low numbers of bats, including common pipistrelle (Pipistrellus pipistrellus), soprano pipistrelle (Pipistrellus pygmaeus), and brown long-eared (Plecotus auritus), within buildings scheduled for demolition. To mitigate this loss and enhance the site, we secured a Natural England European Protected Species Licence and installed 45 bat boxes, including large woodstone multi-chamber boxes and Schwegler 1FDs, across the site.

Simon Dowell, Principal Ecologist
“
It’s wonderful to see so many bat boxes being colonised. Most bat species are crevices dwellers, so it’s essential to design and position roosts that suit their natural habits. Our monitoring shows that bats, once dependent on the old MOD buildings are now thriving in new habitats among Graven Hill’s newly-planted trees and woodlands.

Simon Dowell
Our Principal Ecologist

Monitoring results showed remarkable progress in 2023, with eight of the bat boxes occupied, hosting small numbers of common pipistrelles, with the largest count being over five individuals, and two natterer’s (Myotis nattereri) bats. In 2024, eight-day roosts remained, with fifteen common pipistrelles and one natterer’s bat recorded. This year’s monitoring survey revealed even greater success: eleven roosts were identified, including fourteen common pipistrelles, three soprano pipistrelles, ten natterer’s bats, and four brown long-eared bats. Elsewhere, evidence of bats was also found in three additional boxes, indicating further activity.

Bats thrive at Graven Hill: Record roost numbers signal ecological success

Bats thrive at Graven Hill: Record roost numbers signal ecological success
“
We’re incredibly proud of the positive environmental impact we’re achieving at Graven Hill. The bat project is a fantastic example of how thoughtful planning, ecological expertise, and community awareness can deliver lasting benefits. Our residents and neighbours can be confident that protecting biodiversity remains central to everything we do as the development continues to grow.

Gemma Davies of Graven Hill Village Development Company
said in a recent statement

With Stage 1 of the project nearing completion and Stage 2 moving to secure planning, our licensed ecology team is optimistic that bat populations will continue to thrive alongside the development. Current evidence suggests even more roosts will be discovered in the coming years, demonstrating the success of Waterman’s long-term ecological strategies.

Want to learn more about the Graven Hill project? Click here for the full story.

Find out more about our ecology team and the work we do by visiting this page.