07500 245585

[email protected]

AE Ecology

Ecological Consultancy Services

Bat surveys - useful information to help you understand how we help you deal with bats to help you with your planning application

What does a bat survey involve?


A bat survey will typically come in two stages:  


1 – Visual assessment (sometimes called a Preliminary Roost Assessment, or a Phase 1 survey)

First we would carry out a thorough visual inspection the buildings affected by your project.  We would have a thorough look inside any lofts or attics, or any other accessible voids.  Cellars and basements as well if they are present.  The external features of the buildings would be examined as well, using ladders, binoculars, high powered torches – anything to get us as good a view as possible.


We will be looking for any signs that bats are present, or have been using the site in the past.  However, (and this is quite important) bats are extremely small and secretive and in many cases won’t be visible and won’t leave any signs that they are there.  So our inspection will be able to assess how suitable the building is for bats.  This is based on a range of things, including its age, construction, condition, materials, and importantly, its location in the wider area – such as how close is it to rivers or woodlands, or for more urban properties, are there any good ‘commuting routes’ nearby such as canals or railways, or urban parks.


If we find bats or evidence of bats, then we would usually recommend a further more detailed set of surveys


2 – Emergence / re-entry and roost characterisation surveys (sometimes called Phase 2 surveys)

These are where one or more surveyors (depending on the size of the building and extent of possible roosting areas) monitor the building as it gets dark, to watch for bats emerging from their roosts.  We use specialist bat detectors that can pick up the extremely high frequency calls the bats make.  We can get a pretty good idea of the species at the time, but our detectors record the calls so we can carry out more detailed analysis using specialist software back in the office.


We always use high-end full spectrum or time expansion bat detectors (typically Elekon Batlogger full spectrum and / or Petterson D240X time expansion detectors, or similar).


This Phase 2 work not only allows us to identify the species present, but also to count the likely numbers of bats using the site, identify where the access points are, and gauge the ‘conservation status’ of the roosts.  


We need all this information so we can work with you and your architect / designer to ensure that the necessary measures can be built in to your project to fully address the impacts to bats to the satisfaction of the planning authority. This is the mitigation strategy that you sometimes hear people talk about.


Of course, there may be no bats using your building after all that…  As we said, they are secretive – and they don’t read the textbooks either!  But by carrying out the right level of surveys (as guided by industry best practice, supported by the Government), the planners – and you – can then be satisfied that your project is unlikely to harm bats.


The Chartered Institute of Ecology and Environmental Managament (CIEEM) also has a useful guide here. 

FAQs just about bats


- Why do I need a bat survey?


- What does a bat survey involve?


- How much does a bat survey cost?


- What is a bat licence?


- Why are bats protected?


- Why can’t we just assume bats are here and deal with it that way?


- What if I’ve already started work and I find a bat?


- What if I don’t need planning permission and just want to repair my roof?


- Do I need a bat survey if I don’t need planning permission?


- Do I need a bat survey if I am just applying for Listed Building Consent?


- Why are bats so complicated?!