THE DEFINITIVE GUIDE TO BAT SURVEYS
So, you have put in your planning application. The local planning authority has stated an ecological bat survey is required. You probably have a few questions.
Below is probably the most comprehensive guide to bat surveys available online. We hope this guide answers everything there is to know about bat surveys.
- Why do I need a bat survey?
- Will I need to carry out a survey?
- Deciding if you need bat surveys
- I think we need a bat survey
- What happens during a bat survey?
- What do ecologists look for during emergence of bat surveys?
- Mitigation and compensation for bat species
- What happens after a protect bat species licence is granted?
- What happens if we discover bats after development has started?
- How much does a bat survey cost?
Why do I need a bat survey?
Well, it’s not uncommon especially if you are demolishing a building, breaking into a loft void or live in a bat-friendly area.
Bat survey reports are required for development projects that may affect protected species. Bats along with Newts, nesting birds and many other species are all protected under The Wildlife and Countryside Act (as amended) 1981.
At this point, we’d like to give you some good news. Bats almost never stop your development.
But what is the bat survey and mitigation process? Firstly, a preliminary roost assessment (also known as a phase 1 survey) will take place. This process will highlight any potential for bats to live within your structure.
If the potential is shown, then dusk and dawn or emergence bat surveys need to be completed. These bat surveys need to show whether protected species are present in the area, and how they use the site.
If species are detected, then a mitigation plan is designed to show how you’ll avoid, reduce or manage any negative effects to protected species. Working with your ecologist you need to decide which methods are right for the project you’re working on.
A mitigation licence from Natural England is required. Once received the moving of bats to a new home can then take place.
Will I need to carry out bat surveys?
The simple answer is probably. Yes! you will need a bat survey.
If you plan to carry out development that could disrupt or harm bats or their roosts and your local planning authority has asked for a survey then you will need to carry out a bat survey.
Typically barn conversions, demolition, extensions and tree removal require protected species surveys and potential mitigation.
However, there are a few areas to consider whether your work will be affected.
Deciding if you need bat surveys
Bats and other protected species can be affected by lots of construction work including:
- demolition of buildings
- extensions that affect or alter roof voids
- wind turbines
- barn conversions
- removal of trees or hedgerows
- building or maintenance of roads
You’re more likely to find bats using a building if the property has favourable features such as:
- cracks or crevices in brickwork or fascias
- has a roof with loose or slipped tiles
- has hanging tiles or wood cladding
- is close to woodland or water
- has an uneven roof covering with gaps
- has entrances bats can fly into
- has a large roof area with clear flying spaces
- has large roof timbers with cracks, joints and holes
Some Bat species may hibernate underground in winter. Especially if it:
- is large enough to have a stable temperature
- is close to woodland or water
- is holds humidity
You’re likely to need a bat survey for tree removal if it:
- is in ancient woodland
- is large with good growth
- has natural cavities or split branches
- has damage caused by wind, woodpeckers, rot or lightning
- has loose bark
I think we need a bat survey
If your planning or development has any of the above bullet points ticked then, YES! you need bat surveys.
So what actually happens during the bat survey process?
Well, it’s fairly simple. Bats will almost never stop your development.
What happens on during a bat survey?
So, now you’ve established why you need a survey, you maybe be wondering what happens during the bat survey process.
The bat survey process is straight forward. It generally starts with a preliminary roost assessment and if evidence or potential of bats using the building is found then phase 2 is emergence surveys.
However, if your building holds a confirmed bat roost then the third phase of mitigation and licensing may be required.
If your local planning authority has asked for a survey then you will need to contact a licensed ecologist.
Typically, after a phone or email consultation, the ecologist will then require a visit to your site to undertake a Phase 1 preliminary roost assessment.
Preliminary roost assessments
For most planning permission applications or development projects involving bats, it is appropriate to start with a Phase 1 bat survey also known as a Preliminary Roost Assessment or Scoping Survey.
Preliminary Roost Assessments involve an initial internal and external inspection of a building or habitat to identify the potential for bats roosting or feeding.
Contrary to popular belief, not all UK bat species can be seen hanging in your loft. In fact, only a small amount of species are ‘void dwelling’. The majority of species found throughout Great Britain are what are known as ‘crevice dwelling’, meaning they sleep hidden away between roof tiles, wooden slats etc.
As well as an assessment of the building and surrounding habitat to support bats, a phase 1 bat survey may require a data records search. Meaning, records such as known bat roosts, previous mitigation sites and the location of Site of Special Scientific Interest (SSSI) and Local Nature Reserves (LNR) are obtained. These desk-based assessments are a requirement and are usually purchased from third party biological records centres or county councils.
If the building itself does not show evidence or potential of bat roosts then this information can sometimes be enough to provide an assessment of whether bats are likely to be present on-site and whether they are likely to be impacted upon by the development.
After the data is collected your ecologist will compile a detailed report outlining any further steps, if any, that may be required.
Emergence Bat Surveys
Should evidence or potential for bats be identified via the phase 1 preliminary roost assessment, further bat survey effort may be required. This next stage is known as emergence surveys also known as activity or dusk and dawn bat surveys.
Unlike preliminary roost assessments, which can be carried out year-round, emergence surveys will need to be undertaken between May and September.
The weather conditions must be dry and ideally above 7 degrees celsius.
The bat surveys will be carried out at dusk and/or dawn to establish the species, how many and over what time period bats may be using the structure or habitat.
The team will consist of at least two ecologists, depending on the size and layout of the building or habitat. All elevations need to be covered. Ecologists will survey Dusk or Dawn to see if any bats emerge or enter the building. A return visit will be planned for at least 15 days after. It is important to note that 2 surveys carried out within the same 24 hour period counts only as one survey.
Up to three emergence surveys are required to assist in determining the type of roost which is present and the species using them.
What do ecologists look for during dusk and dawn bat surveys?
The activity/ emergence surveys allow ecologists to identify the usage of the habitat such as;
- Day roosts – individual bats, or small groups of males, are using the area for shelter during daylight hours
- Feeding roosts – where bats, particularly Brown Long-Eared and Horseshoe species feed during the night
- Night roost – where bats rest or shelter between feeding sessions
- Hibernation roost – where bats hibernate over the winter periods
- Transitional or occasional roost – where bats gather at a temporary site before and after hibernation
- Mating site – Males and females gather together in late summer to early winter
- Maternity roost – where babies are born and raised until they’re independent
- Satellite roost – where breeding females roost close to the main nursery colony in the breeding season
- Swarming site – where bats gather in large numbers from late summer to autumn
Mitigation and compensation for bat species
Should evidence show that bats are identified via emergence surveys, then a final step of bat mitigation and compensation will be required.
Working with your ecology consultant you will design a mitigation plan. This involves applying to Natural England for a protected species licence.
However, you will need planning permission to have been granted prior to applying for this licence.
For the licence to be granted, a mitigation strategy will be required that could involve timings of works, installation of bat boxes (both external and internal) and/or creation of a bat loft for void-dwelling species (such as brown long-eared).
In some instances, the best solution can be a stand-alone ‘bat house’. Bat access roof tiles may also provide a good solution to development.
Lower impact measures may require just the installation of a bat box or two. This method is sufficient in the instance of a single crevice dwelling bat, such as a common pipistrelle.
The mitigation plan will address the potential impacts on bats and must avoid negative effects on bat roosts, such as small alternations to project designs or delayed work which may expose the bat roost.
If this is not possible, the use of alternative mitigation measures to reduce the impacts must be implemented.
Mitigation and compensation methods can include:
- Changing work methods or timing to avoid roosting periods. For example, work to be complete during winter on summer roosts.
- Creating new roosts within the same building or on neighbouring structure
- Improving or creating habitats. Such as new foraging areas
- Long term management of habitats
- Roost monitoring after the development
What happens after a protect species licence is granted?
So all the correct paperwork is in place and Natural England has granted your protect species licence. Congratulations.
But what happens next?
The ecologist, architect, construction company and yourself will decide on a date whereby work will be started. The ecology consultant will take one or both of two main steps:
- Implement any compensation measures for void-dwelling bats before works are undertaken.
- And/or – Be on-site to undertake ecological clerk of works measures during a soft break of any areas where crevice-dwelling species are identified.
Once any bats are ‘mitigated’ into the new roost, works can continue as normal.
What happens if we discover bats after development has started?
Stop all work immediately.
Continuing work is likely to be breaking the law if bats are found during building works.
Get in touch with your ecologist who will come and mitigate your bat.
How much does a bat survey cost?
Well, it’s hard to accurately say as it varies greatly. There are many factors to take into account.
Phase 1 preliminary roost assessments and emergence bat surveys range from between £300 – £1000 depending on the ecologists’ fees, location of the development and size or complexity of the site.
As of April 2019, and despite very strong opposition from ecology consultancies including ourselves, Natural England introduced hourly charges for the mitigation licence.
However, as one of the very few ecology companies in the UK which hold a Bat Low Impact Class Licence, on average, our hourly requirements are much less and we are 60 days faster than others in securing your mitigation documents, ensuring to keep costs even lower and to ensure you have no delays in starting your development.