Why have I been asked for a bat survey for my planning application?

This article will explain why you may need a bat survey for a planning application.

I will cover:

  • Bats and Planning Law
  • What triggers the need for a bat survey

I will also highlight common misconceptions and pitfalls.

Bats and Planning Law

In the UK, bats are protected under several pieces of legislation. This means that someone may be committing a criminal offence if they harm bats or destroy their roosts (even if bats aren’t occupying the roost at the time). Local Planning Authorities also have a legal duty to consider impacts to bats when considering a planning application.

The Duty is set out in Section 40 of the Natural Environment and Rural Communities Act, and states that:

Every public authority must, in exercising its functions, have regard, so far as is consistent with the proper exercise of those functions, to the purpose of conserving biodiversity


Section 41 of the Act refers to a published list of habitats and species which are of principal importance for the conservation of biodiversity in England.

The Duty applies to all local authorities, community, parish and town councils, police, fire and health authorities and utility companies.

So – Local Authorities are legally required to think about whether a planning application will harm bats. This has been tested in courts and many authorities now routinely request bat surveys for planning applications that affect any trees or built structures.

Much more detail on wildlife planning law can be read in this write up from the environmental law specialist Penny Simpson here.

What triggers the need for a bat survey for a planning application?

We know that planning authorities are legally required to consider bats in determining planning applications, so what does that mean for you, the applicant.

Local authorities take different approaches to how they discharge their duty to regard bats in planning applications.

The Checklist

Some Local Authorities use a checklist (this is to the one Staffordshire County Council uses, but they are all fairly similar) to determine whether to ask for a bat survey with a planning application.

The checklist provides a consistent approach, which is relatively balanced.  The downside is that it won’t capture all structures with bat roosts, and so whilst it may allow the local authority to discharge their legal duty the applicant could still be developing a site with protected species and at risk of breaking the law inadvertently.

The Blanket Approach

Some authorities will require a preliminary roost assessment (the official term of an initial bat survey) for any application that affects a roof (so this covers most extensions and demolition proposals), and some even require bat surveys for any built structure. These are a couple of the garages I’ve been asked to survey. It isn’t impossible for bats to be found in structures like this, but it is quite unlikely.

While it may be frustrating for the applicant, at least this approach tends to be applied consistently and at an early stage, such as pre-registration of the application. Which brings us to the third approach.

The Haphazard Approach

Some Local Authorities unfortunately still have an inconsistent approach as to whether they will require a bat survey as part of a planning application. This makes it hard for consultants to advise clients and leads to a very reactionary approach. The worst way that this approach manifests is when an applicant is asked at the last minute to submit a bat survey with their planning application. Sometimes this can mean that the survey season (for phase 2 surveys) has finished and this can cause delays of months.

I have worked with several clients who’s architects re-enforce the haphazard approach; they believe they are protecting their clients by not advising them to commission any reports until they’ve been requested by the local authority, hoping to avoid them and save money. This approach can really re-rail a project as the need for a survey may come up at the wrong time. For example:

  • The planning application is granted without a bat assessment, and bats are discovered during construction, causing works on site to stop while this is addressed (possibly after a criminal offence has been caused).
  • The local authority never request the survey, but they use the lack of information about bats as a reason for refusal.
  • The local authority do request the survey, but late in the application process and there is limited time to procure it.
  • The local authority finally request the initial survey, but the survey finds that phase 2 surveys and the survey season is now over, causing delays (worst case 8 months).

The last point comes up quite often. The worst I’ve had in a while was where the client was a developer who had moved from smaller renovation projects to purchase a very large property to demolish and construct flats. His architect knew that bat surveys could be needed, but was aware that budgets were tight and didn’t recommend one. They worked on the project through spring and summer and made an application in September. The authority (Derby City Council) requested a bat survey before the application would be registered. I completed the survey and found that there were several potential roosting features in the building and that phase 2 surveys should be undertaken during the active season, which had just finished. The earliest this could be completed is early June, so this large project was delayed by about nine months, during which the client was paying a commercial mortgage of several thousand points a month. The effort to save a few hundred pounds on a bat survey has cost tens of thousands of pounds unnecessarily. This issue should have been dealt with and de-risked in the early stages of the project.