As we always say here at Blue Willow Heritage, the principles of historic environment conservation form just one cog in the British planning system. Altering historic buildings is often where heritage meets ecology - whether you can spot bats from the get-go, or rather, checking to see if they are present before we go about altering, converting, or even demolishing their habitat! Historic buildings aren't just homes for human beings, whether we like it or not. Read more about this topic below in this Halloween Special blog post!
Why Do I Need to Care About Bats?
We get it - sometimes this process can just appear to be yet another 'planning hurdle'. But all bats are designated as European Protected Species (EPS) which are protected under the Conservation of Habitats and Species Regulations (2017). This makes it illegal to intentionally capture, injure, or kill any bat species - or else, any other activity which can be considered to 'disturb' these animals. Under the Wildlife and Countryside Act (1981), it is also considered an offence to deliberately disturb their place of shelter, including restricting access to a structure in which they reside.
When is a Bat Survey Needed?
Just because no existing evidence dictates that bats are present within your proposed development site does not mean that they are not there. Just as with archaeological remains, absence of evidence does not always equate to evidence of absence! As such, it is recommended that developers assume bats are present unless a recent survey has demonstrated their absence. According to guidance prepared by Natural England, a bat survey is required if at least one of the following clauses applies:
Public records indicate a likely presence of bats in the proposed development area
Existing structures or trees within the site can be considered to provide roosting opportunities for bat species
The development site is close to any natural cliff faces, quarries, or bodies of water
The proposed development comprises the construction of a wind farm close to bat habitats used for foraging and commuting
Does my Building have Bats?
Detailed advice has also been provided by both Natural England and Historic England for assessing whether existing structures within a development site may provide roosting opportunities for bats. Historic buildings are often used by bats due to the lack of natural roosting sites, following deforestation and modern disturbances within their existing habitats.
Contrary to popular belief, bats inhabit cellars as well as roof voids. They are commonly found in traditional agricultural buildings featuring exposed timber beams, weatherboarded or tile hung structures due to enhanced grip, pre-1960 detached structures near woodland or water, pre-1914 structures featuring gabled slate roofs, and other such suitable structures such as bridges and ice-houses. Key signs of possible bat activity in historic buildings include:
Lack of artificial lighting
Close proximity to water or woodland
Presence of large roof timbers and uneven roof tiles
Presence of cracks, crevices, and small exposed openings into the building
Existence of a roof space which becomes warmer in the sun and has sufficient space for flying bats
Presence of hung tiles or timber cladding on south facing walls and has not been occupied for several years
What Does a Survey Involve?
Surveys will identify any bat species present within the proposed development site, in addition to the estimated size of the population. They may also identify the type and importance of the particular roost. Furthermore, entry points used to access the building will also be located, in addition to flight routes and foraging areas in the near vicinity of the structure. Different types of survey work can therefore include: roost surveys (including internal inspections, dawn and dusk surveys, and what is known as 'swarming surveys'), in addition to various kinds of bat activity surveys. Although some preliminary roost assessments can be undertaken at any time of year, most surveys - especially those involving maternity roosts - are undertaken between May and August, and require favourable weather conditions. Typical surveys predominantly include:
Preliminary Roost Assessment (Daytime).
Emergence and Re-entry Surveys (Dusk/ Dawn).
How Do I Commission a Survey?
Your planning consultant will be able to assist you in commissioning the correct surveys for your proposed development project. Our team often provides Heritage Planning documents directly to yourself and your planning consultant who will prepare the planning application and submit all of the required supporting information to the planning portal. Alternatively, where Blue Willow Heritage is is managing your planning application for you, our team will be able to assist you with commissioning the required surveys. This includes collecting quotes from a variety of contractors and booking the required survey at the correct time of year.
These arrangements should be booked in good time, especially when considering long waitlists for such surveys necessitated by the short bat survey season due to the fact that bats enter hibernation in the winter months. Ecologists carrying out the survey must hold an appropriate and in-date survey licence and undertake all work in accordance with the guidelines outlined by CIEEM. It is important to note that Bat Surveys require updating once a set amount of time has elapsed from the date of survey depending on a variety of factors, but usually not before 18 months.
What if Bats are Found?
Developers should ideally seek to avoid disturbing bats altogether. However, where disturbances are unavoidable, appropriate mitigation measures must be explored. Such decisions require an assessment of impact upon any bat species as a result of the proposed development prepared by the ecologist, in order to determine the next steps. Such assessments are required to assess the vulnerability of any bat species present, including their conservation status and the importance of the habitation site on both a local and national level. Developers must also apply for a bat mitigation licence if these animals will be impacted as a result of the proposed development.
Such licences are issued in instances where the proposed development is in the public interest; where no alternative methodology is possible to avoid disturbances to bat populations; and where the scheme will not adversely impact the favourable conservation status of the species. Furthermore, site management and monitoring plans are effective ways to ensure any proposed mitigation measures are effective, and that roosting spaces have remained accessible during and upon completion of the development works.
What are Some Examples of Mitigation Options?
Leaving the bats in-situ in a way in which they will remain undisturbed, including maintaining existing roof voids and roosting places
Alter the timing of any proposed development works to avoid disturbance
Consider appropriate methods of construction to further avoid disturbing the bats
Ensure lighting avoids roost entrances and foraging habitats
Create new roosting places either within the existing structure or a different structure entirely.
Creating new roosting places is often where heritage and ecology must work together to achieve the common goal of sustainable development, as defined by the NPPF (MHCLG). This could include rehousing the bats within an existing structure at the development site, or rather, constructing an entirely new building specifically designed to rehome the bats. This approach is possible even where the setting of listed buildings are concerned, given that the protection of bat species forms part of national legislation and therefore can be considered a public benefit which may offset instances of 'less than substantial harm'. This is an especially powerful argument when the application site concerns a derelict listed building which requires a significant degree of repair works to maintain the structure - something which consequently necessitates the rehoming of the bats who will be inevitably disturbed as part of these works.
Our team is currently working on a number of estate management projects involving the repair and conversion of a number of agricultural structures which have required bat surveys. This includes a derelict Grade II listed longhouse host to a local bat population. Informed by a careful understanding of the heritage significance of the site based on the input of our heritage experts, a new structure has been designed by the project architect within its curtilage to successfully accommodate the bats, whilst remaining subservient and sympathetic to the character of the listed building.
Encountering issues with bat species and your historic building? Or are you planning to develop land of some archaeological potential, but are worried about potential impacts upon local bat populations? Our team is here to help. Blue Willow Heritage offers heritage planning services designed to make the process well-informed and seamless, whilst protecting our natural and historic environment.
For advice on how we can support your development, please feel free to contact us.
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