Preliminary Roost
Assessments
The Preliminary Roost Assessment (PRA) is normally the first assessment undertaken on a structure to determine if bats and their roosts are ‘reasonably likely’ to be impacted by a proposed development.
The PRA has three main purposes:
- To categorise a structure for its suitability to be used as a roosting place for bats
- Record any evidence of bats that may be present
- Make recommendation on the surveys required to determine the presence/likely absence of bats or characterise the bat roost that has been recorded (see dusk emergence dawn re-entry survey)
PRAs are normally undertaken at the planning stage of a development and they are commonly requested by Local Planning Authorities to support planning applications.
Permitted developments not requiring planning permission may also require a PRA for bats to be undertaken in order to demonstrate that appropriate care has been taken to avoid impacts to bats and their roosts before the commencement of a project.
Searching for signs of bats
A PRA consists of an external and, where safe to do so, an internal inspection of a structure. A search is undertaken to record any access points that could lead to internal voids or any gaps and crevices that could be used by roosting bats, often referred to as Potential Roosting Features (PRFs).
In addition, a search for signs of bats such as bat droppings, urine splashes and feeding remains as well as bat specimens (live and dead) is undertaken.
What you need to know about a PRA for bats
Our approach
At Arun we regularly undertake PRAs for bats as part of planning applications, and for statutory undertakers of permitted developments. Our PRAs for bats follow Bat Conservation Trust best practice guidelines and CIEEM competency guidelines.
We have in-house specialist Bat Licenced Ecologists who are experts in their field and hold the relevant licences to survey bats, ensuring accurate and efficient data collection.
Classifying a structure for roosting potential
The age, condition, proximity to certain habitat (such as woodland or waterbodies) and geographic location, are key factors that define the term ‘reasonably likely’ in the context of bats being present and the suitability category assigned to the structure.
There are five categories that can be assigned:
Where there is certainty the structure is not suitable for roosting bats.
Where bats may use a feature opportunistically, but the structure and surrounding habitat mean the structure is: unlikely to be used on a regular basis, or support large number of bats or important roost types.
A structure that could be used by bats but is unlikely to support roost types of high conservation importance.
A structure suitable for use by larger numbers of bats and that could support roost types of conservation importance.
Where the presence of a bat roost has been confirmed.
When can a PRA can be undertaken?
A PRA can be undertaken at any time of the year and is not limited to the bat survey season. It can often be easier to spot potential roosting features (PRF’s) during the winter months when there is less foliage.
It is important to note that while PRA surveys are not time restricted, dusk emergence and dawn re-entry surveys to determine presence/absence can only take place between May-September (with certain criteria that need to be met in this period).
What next following a PRA?
While the PRA surveys can be used to confirm the presence of bats, the PRA alone is not deemed a proportionate survey effort to conclude the likely absence of bats, unless the structure is deemed to be of negligible suitability to support roosting bats.
Scenario 1: If the building is classified as negligible then the PRA report can be used to submit with a planning application or listed building consent or as evidence of an assessment for any permitted developments.
Scenario 2: The most common scenario is that further surveys such as dusk emergence and dawn re-entry or bat hibernation surveys will be required to demonstrate that development proposals will not impact bats. Further surveys should be factored in at the earliest stage as they are time sensitive.
FAQs
Bats are very cryptic animals that often coexist undetected unless targeted surveys are used to determine their presence. Local Planning Authorities are legally obligated to assess the impacts of protected species such as bats when considering a planning application. It is a requirement that an impartial and suitably qualified Bat Licenced Ecologist undertakes a Preliminary Roost Assessment to determine a building’s suitability for bats. As such, planning permission is unlikely to be granted without at least a PRA survey being undertaken on works to an existing building.
A Preliminary Roost Assessment is not a time constrained survey and can be undertaken at any time of year. However, it is important to note that many of the additional surveys often recommended in PRA reports to determine presence/likely absence of, or characterise, a bat roost, are time constrained. Completing additional surveys at the correct time of year is likely to be a requirement to secure planning permission and bat mitigation licences (such as a European Protected Species Licence).
Example: Undertaking a PRA survey in September may mean that additional bat surveys are required to demonstrate that a proportionate survey effort has been made and to determine the presence or likely absence of bats. If all dusk emergence and dawn re-entry surveys are completed after September, the survey effort may not be accepted by the Local Planning Authority or Natural England, as this does not provide the correct coverage of the bat survey season. In this scenario it would be better to wait until the following May to complete the surveys.
Typically a Preliminary Roost Assessment survey is accepted by a local planning authority for 12 months.
It may be possible to secure planning permission with just a PRA survey if a building is categorised as having negligible suitability for roosting bats during a PRA survey. If a building has any potential roosting features present, in almost all circumstances, further dusk emergence or dawn re-entry surveys to determine the presence/likely absence of bats will be required by Local Planning Authorities. In line with biodiversity and geological conservation: circular 06/2005, further dusk emergence and dawn re-entry surveys should be completed prior to submitting a planning application and should not be conditions of planning.
At Arun Ecology we will provide you with a questionnaire prior to any survey on the information we require to complete the survey, predominantly focusing on land access and health and safety. As an insight we require the following information:
- Land parcel and building access information
- Any tenants present who have been informed of the survey
- An asbestos register and/or a structural report (we can’t complete any internal surveys without these)
- Any other hazards that might be present at the site (such as livestock or plant activity)
Helping to address the ecological
and climate crisis
At Arun Ecology it’s not all just about driving business. We want to contribute to addressing the challenges of our time to ensure a prosperous future for the next generation.
So, as part of our service, each time you commission us we are committed to planting one tree within the UK, through our partnership with Creating Tomorrow’s Forests.
Watch this space to find out more about how we are contributing to nature recovery and tackling climate change.
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