Bat Surveys Explained

By Rachel on the 16th February, 2017

Want to understand the bat survey process? This blog aims to explain all aspects of the bat survey process.

Brown Long-eared Bat (Plecotus auritus)

We’re often asked why bat surveys are needed, what happens if bats are present in a building or structure, and what bats mean for a project or development. This is a simple guide to bats, legal obligations and planning applications. We’ve also produced a handy infographic A Guide to Bat Surveys to guide you through the bat survey process.

Why, When and Who?

Why do I need a bat survey?

The simple answer is that bats are legally protected and you would be breaking the law if your works were to impact upon them. All bat species, their breeding sites and resting places (called roosts) are fully protected by law, and roosts are protected even if no bats are present. So, if there’s a chance that your works may impact bats you will need a survey.

Because bats are protected, local planning authorities must consider bats during the planning process. Local planning authorities are likely to refuse planning permission if applications could impact bats and don’t include the relevant survey information.

But why are bats so heavily protected?

The main reason for their protection is that populations have significantly declined in the UK over the last century. These declines are due to many factors including loss of natural habitats such as woodlands.

What works are likely to impact bats?

Many bat species use buildings and structures to roost including houses, churches, castles, trees, barns, caves, mines, bridges, culverts, and tunnels. Works to any of these types of buildings or structures could impact bats.

Local planning authorities often have their own specific trigger lists for when bat surveys are needed, but if you’re not sure if you need a bat survey either check with your local planning authority or contact us. We’ve also provided the Bat Conservation Trust’s Trigger List for bat surveys.

Who should carry out a bat survey?

When commissioning bat surveys you should check that the surveyor holds a survey or research licence from the relevant Statutory Nature Conservation Organisation (either Natural England, Natural Resources Wales or Scottish Natural Heritage) which permits the surveyor to access roosts where bats would be disturbed. Surveys carried out by unlicensed ecologists risk being disregarded by local planning authorities, meaning wasted time and extra costs to you. Smart Ecology surveyors are experienced, fully licenced bat ecologists.

The Chartered Institute of Ecology and Environmental Management have produced a detailed guide to engaging an ecologist.

The Process

1. Preliminary roost assessment

If you have checked the trigger list and found that your proposed works may impact upon bats then you will need to commission an ecologist to undertake an initial preliminary roost assessment. This involves a daytime inspection of the building or structure to look for evidence of bats (e.g. droppings, feeding remains) and assess the potential for bats to roost. The ecologist will thoroughly inspect the outside and inside (including lofts) of the building/structure. Binoculars will be used to look for any potential roost sites (e.g. raised roof tiles, gaps behind felt in the loft) and an endoscope may be used to check crevices. A preliminary roost assessment can be undertaken at any time of the year.

If the preliminary roost assessment finds no evidence of bats and concludes that the building/structure has negligible potential for roosting bats then no further surveys are likely to be required. Smart Ecology would provide you with a preliminary roost assessment report to support your planning application.

2. Emergence / re-entry surveys

If evidence of bats is found, or the building/structure is considered to have potential for bats, then further surveys will be required. These are emergence and re-entry surveys which involve surveyors watching potential access points at dusk and dawn to observe if bats leave or enter the building/structure. These surveys can only be carried out in good weather conditions between May and September and should to be spread across the survey season, at least a couple of weeks apart.

If bats are found during emergence and re-entry surveys then Smart Ecology would provide a bat survey report and mitigation strategy to support your planning application. The mitigation strategy would provide measures to ensure that bats are not negatively impacted and can continue to roost in the building/structure or a replacement roost site.

3. Mitigation licence

If bats are present and impacts to bats cannot be avoided, it will be necessary to apply for a European Protected Species mitigation licence from the relevant Statutory Nature Conservation Organisation after planning permission has been obtained. These licences permit works affecting bats that would otherwise be illegal and can take up to 30 days to be granted. At Smart Ecology we are experienced at preparing and obtaining these licences.v

Feel free to get in touch with us if you would like to discuss a project or request a free quote.



Rachel Barber

Rachel has an MSc (Distinction) in Ecology and Management of the Natural Environment from Bristol University. Prior to founding Smart Ecology Rachel worked for a respected Gloucestershire ecology consultancy and has also worked for a large multidisciplinary consultancy. Rachel is a full member of the Chartered Institute of Ecology and Environmental Management (MCIEEM). Rachel is an experienced ecologist specialised in European Protected Species (EPS). She holds survey licences for bats, hazel dormice and great crested newts.