Why do I need a bat survey?

Bat are protected by law making it illegal to undertake work that could impact them or their resting places. Indirectly the habitats in which bats rely on for foraging or for movement around the landscape can also be protected if the loss of them could disturb a known roost or protected site.

In England, Scotland and Wales it is illegal to:

• Intentionally or deliberately kill, injure or capture bats;
• Deliberately disturb bats, whether at roost or not;
• Damage, destroy or obstruct access to bat roosts;
• Possess or transport a bat or any part of a bat, unless acquired legally; and
• Sell, barter or exchange bats, or any part of a bat.

The usual ‘trigger’ for a bat survey requirement is a request from your planning consultant, architect or the local planning authority so it can be submitted with a planning application. Bat surveys can also be recommended following the results of an ecological scoping survey or preliminary ecological appraisal.

There are 18 species of bat in the UK (17 breeding) and new species of bats pop up across the southern half of the UK all the time. Bats are protected because they show a steady decline in numbers largely due to the loss of high quality habitats and the conversion of buildings traditionally used by bats such as barns.

What do we do for a bat survey?

So you require or have been asked to provide an assessment of your site or property for bats, what do we do?

Bat surveys follow a process of different surveys depending on if evidence of, or potential for bats is identified. The first step is called a preliminary roost assessment (PRA). This survey includes a physical inspection of a potential bat feature such as a building, bridge or other similar structure. An experienced Ecology by Design ecologist would inspect the internal and external areas of the structure searching for evidence of the presence of bats or features that could support roosting bats. If bats are known to be present or their is a high likelihhod the survey will be led by a suitably experienced ecologist that holds a license for the survey issued by Natural England, Scottish Natural Heritage or Natural Resources Wales. A PRA can be undertaken at any time of year.

If bats (or potential for bats) is identified and they cannot be avoided, further survey work may be recommended which is normally in the form of emergence/ re-entry surveys. These surveys are conducted at night and involve surveyors recording bats entering or emerging from a feature on the structure. Emergence/ re–entry surveys range from one to three visits and can be undertaken between May and the end of September and are ideally spaced a month apart.

For sites with trees that could be impacted, a preliminary ground level roost assessment is undertaken to assess each tree (or groups of trees). If features are identified that have potential for bats additional off the ground surveys can be undertaken to physically inspect each feature utilising either mobile platforms or qualified tree climbers.

For sites that offer known or potentially suitable foraging habitats or commuting features where there would be a significant impact i.e. removal of hedgerows/ trees or loss of grassland or water features, activity surveys are undertaken. Activity surveys can be undertaken between May and September and involve a walked route around the site stopping at specific points (listening stations) to record bat activity around the site. The number of visits would depend on the size and quality of the habitats but can range from three visits (one in Spring, Summer and Autumn) and up to fourteen visits (twice per month from April to October).

Other surveys can also be undertaken but are very specialist and specific to certain situations such as trapping using nets, radio tagging and backtracking.

Bat Licence Application and Mitigation

If a bat roost is identified and the scheme cannot be altered to remove impacts upon bats, mitigation may be required to mitigate for the loss, disturbance or modification of a roosting site.

Licences and mitigation can range widely in price and the amount of input required depending on the impact, species of bat and budget. Schemes may include the installation of bat boxes either within or retrofitted externally to a building or tree or could in a high impact situation include the construction of a building or roof feature designed for bats. We have never had a mitigation scheme refused and work hard with our clients to provide cost effective solutions that does not destroy their scheme.

Work that impacts bats will generally be undertaken under a derogation licence issued by a statutory authority (Natural England, Natural Resources Wales, Scottish Natural Heritage) and would allow work that would normally be considered illegal. There are two types of licence available; a full licence for high impact situations and a low impact licence for those situations affecting low numbers of bats.

External Resources

[Bat Conservatuion Trust: Planning Law][1]