Bat surveys at Elvaston Castle
With known bat roosts in the temple, Baker Consultants was commissioned by Derbyshire County Council to undertake a bat survey and scope what was initially thought to be simple mitigation work.
Survey techniques employed included dusk/dawn surveys and a visual survey of the roof space. In total, seven bat roosts were discovered within the building, which is surprising when you realise that the building is only 4 by 4 metres in size, had water pouring in through the roof and was exposed to the elements.
Baker Consultants’ licensed bat workers drew up a detailed mitigation plan and were available on site to supervise the building works. What made this job particularly difficult was the range of roosts, which include a maternity roost and a hibernation roost.
Generally in dealing with hibernation roosts, the best time to work is during the summer. However, in this instance this has a direct conflict with best practice for maternity roosts, where the best time to work is during the winter months when bats have moved to hibernation sites.
Despite carefully planning prior to the project commencing, the project team did meet with a number of significant issues, most notably the inclement weather: a foot of snow and temperatures of -18C. Although the complete removal and replacement of the roof was extremely invasive, no bats were knowingly disturbed throughout the works and the majority of workers had a genuine interest in the bats in the building.
We ensured that the construction company (C R Crane and Sons, Leicestershire) used hand tools for the whole job and, more importantly, asked advice if they were in any doubt regarding an issue relating to bats. It is important that site sub-contractors are aware of the issues around protected species in order to comply with legislation and avoid potentially harmful mistakes, particularly as bats and their habitats are protected under the Wildlife and Countryside Act 1981 (as amended by the Countryside and Rights of Way Act 2000) and by the Conservation of Habitats and Species Regulations 2010.
The smooth running of the project was facilitated by Baker Consultants’ consultative approach to the project and by regular meetings organised by the team at Derbyshire County Council.
Working with the Simpson and Brown Architects, Baker Consultants designed replacement roosting features, which were unobtrusively built into the refurbished building, and additional roosting opportunities, which were installed around the temple. The project has proved to be a success with bats once again using the building. To date, we have recorded three pipistrelle bat roosts and a significant number of brown long-eared bat droppings inside the building. Although the hibernation roost has not yet been inspected, we are hopeful that the bats will have returned and continue to use this part of the building.
Following the end of the project, Baker Consultants will make a final visit to monitor the effectiveness of the mitigation. Records will be submitted to the biological records centre run by Derbyshire Wildlife Trust (former residents themselves of Elvaston castle).
“Baker Consultants’ approach to the project kept it to time and budget whilst ensuring that our legal obligations regarding protected species were met to the letter, vital for anyone and certainly for a local authority project.
Well done to all involved in the project, the bats have probably been here since the building first existed so hopefully they will now have a roost for the next hundred years.”