What is a Bat Survey?
If you are renovating, converting or modifying an old building, you may need to conduct a bat survey. A bat survey will be required to check for the presence of bats within the building, and should be undertaken if there is ‘reasonable likelihood’ that bats are present.
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Bat Survey Guidelines from Ecology by Design
This guide covers the following questions:
Should you get a bat survey before getting planning permission?
Do you need to get a bat survey even if you think you do not have bats?
WHY DO YOU NEED A BAT SURVEY?
You will likely need to undertake a bat survey when there is any chance that you may interfere, disturb or disrupt a bat in its natural habitat. This is because bats are a recognised protected species, meaning that, by law, it is an offence to disrupt their environment . A bat survey can ensure you take all the necessary steps to avoid long term damage or impact to a pre-existing bat population, while still seeing your project come to fruition. A bat survey will be needed to be conducted during bat survey season, and will need to be conducted by a licensed bat surveyor. An experienced bat surveyor will look at the condition of external features on the building, including roofing tiles/slates, eaves and chimneys. This will assess the potential for roosting bats.
To satisfy the local planning authority, the relevant processes must be in place to ensure minimum disturbance to bats as a protected species. Bats are protected by law, so bat surveys must be taken seriously by developers and homeowners. They are protected by international and domestic legislation; namely, the Wildlife and Countryside Act of 1981 and Conservation of Habitats and Species Regulations 2017.
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WHAT KIND OF WORK WOULD AFFECT BATS?
Demolishing buildings;
Extensions of buildings / roof modification;
Wind turbines;
Barn conversions;
Removals of trees/ hedgerows; and
The building or maintenance of roads.
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HOW LONG ARE BAT SURVEYS VALID FOR?
Typically for one to two years due to the changing habits of bats, who may find new roosts with each new season. There is a risk that out of date bat surveys can impact building plans and will need to be addressed at a later date, therefore both private developments as well as commercial developments should be mindful of ensuring the bat surveys conducted are in date.
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WHERE DO BATS ROOST?
Some common places where you may expect to find bats include:
Agriculture buildings/ stone constructions/ exposed beams;
Buildings with weather boarding or hanging tiles;
Buildings needing conversion, modification, or removal;
Buildings with minimal artificial light;
Buildings close to woodland or water;
Older buildings with cracks and crevices;
Buildings with easy access; and
Buildings with large roof area and clear flying spaces.
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ARE BATS PROTECTED?
Yes, bats are a protected species in the UK, and it is an offence to do any of the following:
Kill, injure, capture a bat;
Intentionally disturb bats in their natural habitats, if this disturbance might impact the bat’s ability to survive/ breed/rear or nurture their young;
Damage or destroy a roost, regardless of whether bats are present or not; and
Obstruct access to a roost.
If you believe that there is a reasonable chance of the presence of bats on the site you are working with, and are keen to know what to do next, and what is required of you by law, read on. Not only can Ecology by Design offer experienced services, we can also advise you on what to look out for and where to expect bats.
There are currently 18 species of protected bat in the UK, 17 of which are known to also be breeding in the UK.
The 18 species of bat found in the UK are listed below, but for more information, check out Ecology by Design’s guide to common questions about bats in the UK.
Alcathoe bat
Barbastelle bat
Bechstein’s bat
Brandt’s bat
Brown long-eared bat
Common pipistrelle
Daubenton’s bat
Greater horseshoe bat
Grey long-eared bat
Leisler’s bat
Lesser horseshoe bat
Nathusius' pipistrelle
Natterer's bat
Noctule
Serotine
Soprano pipistrelle
Whiskered bat
Greater mouse-eared bat
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SHOULD YOU GET A BAT SURVEY BEFORE GETTING PLANNING PERMISSION?
It is advised that you carry out a bat survey as early as possible in the process, particularly if there are any signs of potential bat activity. This will save you having to consider the costs of mitigation later on in a project, at a point where it may be too late, and you may find you are engaging in illegal activity. This will also ensure you can implement any necessary actions before the bat survey season begins.
Don’t forget...
Before any project, no matter how big or small, be sure to carry out the necessary steps to ensure you are working within legislation. It is not uncommon for individuals can be fined for ignoring legislation.
It is for these reasons why it is so important to consider whether a bat survey is necessary to undertake before getting planning permission.
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DO YOU NEED TO GET A BAT SURVEY EVEN IF YOU THINK YOU DO NOT HAVE BATS?
Yes, even if you don’t think you have bats, if the building or development even has a small chance of bats being present, it is worth commissioning a survey to ensure no bats are present. If there was a ‘reasonable likelihood’ of bats, you’d be better off undertaking a survey than leaving it to chance.
The good news is that Preliminary Roost Assessments can be conducted all year around, so, no matter where you are in the process, you can undertake a bat survey to find out for sure if there are any bats or the potential for bats to be present on the site.
This gives you the advantage or time to either:
Amend plans, so you do not impact the bats; and
Put in place a mitigation scheme to ensure that the development meets the requirements of third parties and regulations.
As a European protected species, local authorities are obliged to ensure the conservation of biodiversity. This in turn encompasses the requirements of the wider European Habitats Directive.
Within the PRA, experienced ecologists such as Ecology by Design will undertake a physical inspection of a potential bat feature such as a building, bridge or similar built structure. Ecologists will inspect both the internal and external areas of the structure, searching for evidence of the presence of bats as well as any noticeable features that could support bats. It may involve the assessment of tree roosts as well as roosts within an existing building.
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‘POTENTIAL’ FEATURES
Bats can be very cryptic and often homeowners are completely unaware they are sharing a building with a bat roost. Ecologists look for the actual presence of bats but often there are features that cannot be adequately inspected such as cavity walls, or broken, damaged or missing roof tiles. The PRA will also identify these ‘potential’ features and highlight if further survey of these features is required.
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WHAT TO DO IF BATS ARE DISCOVERED
If bats are discovered after a PRA, then phase 2 of the survey will include a more detailed assessment of the area to establish how the feature is being used and by what species. Unlike the PRA, the phase 2 survey must be conducted within a certain time period. The Phase 2 Surveys should be conducted between May and September, as this is when bats are most active, and partake in breeding activities, with notable activity in and around roosts. This is generally referred to as the bat survey season, and it is vital that any necessary bat survey preparation bears this timeframe in mind.
This enables ecologists to actively measure their presence, in order to establish the exact impact of a potential project on the bats present.
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ACTIVITY SURVEYS
The phase 2 surveys are also known as ‘Activity Surveys ’ as they enable ecologists to take a closer look at the exact activities of bats. Surveys of this manner may initially take place in daylight in order to establish behaviour patterns, locations of roosts, droppings, carcasses etc.
Ecologists may undertake a walked route around the site in order to establish potential bat roosts, and identify listening stations to monitor bat activity. Depending on the size and quality of the habitats, more visits will be conducted to monitor and record bat activity. Each individual species have specific requirements and use different features depending on the exact situation, and therefore surveys may also involve night time visits involving infrared/ thermal cameras (see video), handheld bat detectors, fixed bat detectors, radio tagging, back tracking and trapping using nets.
If it is impossible to avoid impacting on bats, another survey that may be conducted is an emergence / re-entry survey. These surveys are conducted at night, and involve surveyors recording bats entering and emerging from specific locations.
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BAT MITIGATION SCHEME
If a bat roost is identified, and the scheme cannot be altered to remove the impact on existing bat species, then a mitigation scheme will likely be needed to be put in place. Essentially, this is to mitigate the loss or disturbance / modification of a roosting site. The amount of input from relevant parties depends on the amount of impact on the species of bat.
Some mitigation or compensation schemes include:
Changing the location of the work itself;
Changing the work methods and timing to avoid bats;
Creating/restoring/improving existing roosts;
Replacing any roosts that are damaged or removed;
Managing and maintaining habitats in the long term; and Monitoring the roosts status’ after the development.
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HOW MIGHT A BAT BE AFFECTED BY A DEVELOPMENT?
There will be plenty of ways a bat could be disturbed or disrupted with a development plan.
For example, some short-term impacts include:
Human presence at site;
Increased noise and light; and
Changes to the area layout, temperature, humidity.
Long term impacts include:
Reduced roosting space, loss of roosts altogether;
Changed entrance positions/ sizes;
Ventilation affected;
Increased human activity in general; and
External lighting near flight paths / commuting routes.
Mitigation schemes may include:
The installation of bat boxes within or externally to the building or tree that is affected; and
Construction of a building or roof feature designed for bats.
Some mitigation can be undertaken following an approved method, however a lot of mitigation work can only be undertaken by acquiring a bat licence. The type of bat licence should be discussed with an ecologist but may include either a full licence or bat mitigation class licence (BMCL). The BMCL is only available for certain species and is aimed at low impact situations and is a special type of licence restricted to only some ecologists.
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HOW TO GET A BAT LICENCE
Licences can be issued for specific purposes, issued under the Habitats Regulations. You will be breaking the law if you carry out work that could impact bats without sorting out a bat licence first.
You can find out more about bat licences here. If you find that your development cannot avoid disturbing bats, then you will need to apply for a mitigation licence.
Before taking on any project, avoid nasty surprises later on and potentially legal fees by ensuring you have taken all the necessary steps from an ecological point of view. When referring to bat surveys, this means taking the necessary precautions if there is any slight evidence to suggest that bats may be present in the area. It is best to work with an experienced specialised ecologist, who can conduct all the necessary surveys with both the licensing required as well as the expertise and knowledge.
If you think you may need our help, Ecology by Design are here to work with you every step of the way. For more information, you can read our case studies, check out our ecology blog, or contact us to find out more.
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PRELIMINARY ROOST ASSESSMENT
A preliminary roost assessment can be undertaken at any time of the year. The assessment is an internal and external inspection of the building which is subject to planning. An internal inspection of any lofts and cellars will also be undertaken. Within the loft, all areas will be inspected for the potential presence of bats and any evidence of bats such as droppings, feeding remains or staining. This includes searching the ridge and looking around any hanging felt or within brick cavities.
The building will have been classed as having ‘potential for bats’ if bats or bat evidence is found or if there are features such as gaps in roofing tiles that are suitable for crevice dwelling bats (which cannot be adequately inspected). If the building has potential for bats, further surveys may be required in the form of emergence and re-entry surveys. Where droppings are found, these are collected as a complementary method to the emergence/re-entry surveys, the droppings are sent off to a laboratory for DNA analysis to tell us the species of bat present. This is often used because bat poo can be difficult to identify to species level and some species such as the Long-eared bats require analysis to differentiate them if not physically caught by hand.
If no evidence of bats or no potential for bats is found, then no further surveys are required and we will provide you with a letter based report to submit alongside your planning application.
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EMERGENCE/RE-ENTRY SURVEYS
The aim of the emergence/re-entry surveys is to observe and record bats emerging or re-entering from features identified during the preliminary roost assessment. Emergence and re-entry surveys can be carried out from May to September, following guidance from the Bat Conservation Trust Bat Surveys for Professional Ecologists: Good Practice Guidelines.
If the building has high potential i.e bat evidence has been found or the building has multiple features suitable for roosting bats, then three surveys are required. Buildings with moderate suitability will require two surveys and buildings with low suitability will require one survey visit.
Emergence surveys are undertaken 15 minutes before sunset and last for up to two hours after sunset, re-entry surveys start two hours before sunrise and last until sunrise or for 15 minutes after sunrise depending on the level of bat activity. The number of surveyors needed to carry out bat surveys will depend on the building size and number of features to be surveyed. Where sites are complex we utilise modern technology such as the use of thermal imagery, automated detectors and drones.
Although surveys can be undertaken between May and September, for buildings with low and moderate suitability, at least one survey has to be between May and August. Buildings with high suitability have to have two surveys between May and August. The levels of bat activity are highly dependent on weather, types of roost and season. It is best practice to spread bat surveys out across the survey period, this will allow us to detect and identify the different types of roosts present on site.
Once the survey has been completed we will provide you with a report which will contain the survey findings, analysis and recommendations on how to progress with the development.
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WHY DO I HAVE TO DO A BAT SURVEY?
A bat survey is required to provide information on the species of bat, type of bat roost and the features used by the roosting bats. We collate the information from across the bat survey season to then provide pragmatic mitigation proportionate to the roost type and the species present.
Bats are fully protected by both UK and European legislation. Therefore, where a bat roost is to be affected by a development then a Natural England, Natural Resources Wales or Scottish Natural Heritage licence will be required.
A licence to undertake works that may disturb or destroy a roost cannot be applied for until a full bat survey has been completed.
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WHAT IF I HAVE PLANNING?
Although planning may have been granted, bat surveys may still be required. Planning permission does not override legislation and therefore there is still a legal requirement to ensure bats are not impacted by the new development. If you have planning and the proposed development may risk bats or there is a condition for a bat survey the first stage is to appoint an ecologist to carry out a preliminary roost assessment.
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CLASS Q PERMITTED DEVELOPMENT
There are certain circumstances where planning permission is not required for the change of use of a building. Advise should be sought from an ecologist as early as possible.