Bat Surveys in Wales
Bat Surveys in Wales
When They’re Required for Planning and When They Can Be Carried Out
Bat surveys are one of the most common ecological requirements for planning applications in Wales. If your project involves buildings, trees, or land near suitable habitat, there’s a strong chance your local planning authority will request survey work.
Understanding when surveys are needed and when they can be undertaken is key to avoiding delays.
When Are Bat Surveys Required?
In Wales, bat surveys are required where a development has the potential to impact bats or their roosts.
This typically includes:
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Conversion, alteration or demolition of buildings
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Works to roofs, loft spaces or structures with crevices
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Development affecting trees with roost potential
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Sites close to woodland, watercourses or high-quality habitat.
Even where no bats are visible, the potential for bats is often enough to trigger a survey requirement.
Local planning authorities expect sufficient ecological information at the point of application. Without it, applications can be delayed or refused.
The Legal Context
All UK bat species and their roosts are fully protected under legislation including the Conservation of Habitats and Species Regulations and the Wildlife and Countryside Act 1981.
This protection applies whether bats are present at the time or not.
As a result:
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Roosts must not be damaged or destroyed
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Bats must not be disturbed
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Access to roosts must not be obstructed
Planning authorities must take this into account before granting consent.
What Types of Bat Survey Are There?
Bat survey requirements are usually determined through a staged approach:
Preliminary Roost Assessment (PRA)
A daytime inspection to assess whether a building or tree has the potential to support bats.
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Identifies features such as cracks, voids and roof spaces
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Determines whether further surveys are required
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Can be carried out at any time of year
Emergence and Re-entry Surveys
If roosting potential is identified, activity surveys will be required.
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Dusk emergence surveys (bats leaving a roost)
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Dawn re-entry surveys (bats returning)
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Used to confirm presence/absence and roost type.
Additional Survey Work
Depending on the site, further surveys may be needed, including:
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Activity surveys across a site
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Hibernation surveys
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Roost characterisation surveys
When Can Bat Surveys Be Carried Out?
Year-Round Surveys
Some elements of bat survey work are not seasonally constrained:
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Preliminary Roost Assessments
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Desk studies and ecological appraisals
These are typically the first step and can be undertaken at any time.
Seasonal Survey Window
Bat activity surveys are season-dependent and must be carried out when bats are active.
The main survey season in Wales is:
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April to September – general activity surveys
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May to August – optimal period for emergence/re-entry surveys
Survey timing is critical, and availability can become limited during peak months.
Winter Surveys
In some cases, surveys may be required during winter:
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November to March – hibernation surveys
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Relevant where structures or features may support hibernating bats
Avoiding Delays to Your Project
The most common issue we see is projects missing the survey season.
If activity surveys are required but not completed in time:
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Applications may be delayed by several months
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Surveys may need to wait until the following season
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Programme timelines can be significantly affected
Early advice and planning are essential.
What Happens If Bats Are Found?
Where bats are confirmed, development can usually still proceed — but it must be carefully managed.
This may involve:
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A licence from Natural Resources Wales
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Mitigation measures such as bat boxes or roost provision
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Timing restrictions on works
We regularly support clients through this process to ensure compliance while maintaining project momentum.
How We Can Help
We provide a full range of bat survey and ecological services across Wales, including:
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Preliminary Roost Assessments
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Emergence and re-entry surveys
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Activity and transect surveys
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Hibernation surveys
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Licensing and mitigation design
We work closely with clients, planners and architects to deliver practical, proportionate advice and keep projects moving.
