Learn More About Bat Emergence Surveys
The decline in bat populations across the 18 native species in the last 50-100 years has been linked to the advance in the footprint of our towns and cities and subsequent loss of high-quality bat roosting and feeding habitat throughout the UK.
In response to this, the government has transposed the EC Habitats Directive in the UK through the Conservation of Habitats and Species Regulations 2010, effectively criminalising the disturbance of bats and their habitat. This doesn’t mean that the evidence of bats or their habitats on your site can stop you from obtaining a planning application, or that bats can immediately and indefinitely ruin your project. It does, however, mean that your local planning authority will need to see proof that you can provide mitigation appropriate to the species of bats, population and roost type, or undertake your development in a way to avoid disturbing bats entirely if evidence suggests that bats are present.
Bat surveys fulfil this obligation, starting with a Preliminary Roost Assessment (PRA) / Scoping Bat Survey before moving onto Bat Emergence Surveys – a secondary form of bat survey that, once it has been established that bats are present, enables a licensed ecologist to use specialist equipment such as bat detectors to gather more detail on bats flying to and from each individual bat roost across clear flying spaces and flight paths.
What is a Bat Emergence Survey?
Following the completion of a Preliminary Roost Assessment (PRA) to find bats and determine the scale of the presence of bats on a property or site, a Bat Emergence and Re-Entry Survey (BERS) is phase two in the initial assessment process. As such, the results of a PRA – i.e. evidence of bats being present such as identification of bat droppings, the feeding remains of prey, living or dead bats, or suitable roosting features (e.g. hanging tiles or a large roof area that could pose high potential for roosting bats) – will gauge whether or not a BERS is needed.
Once it is established that a BERS survey is necessary, an ecologist will visit the site and monitor the entry and exit points to gather information on the bat species, location and population. The data gathered from this exercise will be used to gauge the presence of bats on the site as well as the affect bats may experience as a result of the permitted development work.
A suitably qualified ecologist will analyse the site or property at length and record visual and sound of inhabiting bats before compiling their findings and effective recommendations into a BERS report that can then be submitted to the local council as part of the application for planning permission. With the purpose of supporting planning applications on small or large plots of land and, in some cases, multiple sites at a time, a physical inspection of this nature could involve several surveyors in order to fully undertake an internal and external inspection of the site.
Why do you need a Bat Emergence Survey?
Under the Wildlife and Countryside Act 1981 and the Conservation of Habitats and Species Regulations 2017, bats are protected alongside other European protected species, both domestically and internationally. Over the course of any project that could interfere with or endanger inhabiting or roosting bats such as building, extending or demolishing of properties, producing wind turbines, barn conversions, and removing trees or hedgerows, the local planning authority will need proof that rules are being followed to avoid human activity disturbing bats, creating reduced roosting space or causing unnecessary harm to nearby bat species.
In a Bat Emergence Survey, a qualified ecologist will record data in regards to the type of species on the site or property, entry and exit points that could indicate locations of habitats, and estimate the number of bats present. The bat roost status is also an important factor as the type of bat roost can indicate a different purpose. For instance, common examples of bat roosts include day roosts, night roosts, hibernation roosts, maternity roosts and transitional roosts. Using this information, an ecologist carrying the necessary bat licence can form an understanding of the specific bat habitats on the site and, alongside the proposed development plans, develop mitigation measures that enable the project to go ahead despite the presence of bats.
The ecologist’s recommendations will then be put forward to the local authority to support the developer’s planning application. If the local council then decides to grant a planning application to the developer as a result of the ecologist’s report, the developer will be eligible to make the necessary bat survey licence applications, enabling them to make alterations based on the predetermined mitigation measures.
Additionally, the local authority will have separate reasons for requiring this type of assessment. Primarily, a local council will need a BERS report as it caters to two primary factors – remaining within the rules of legislation that protects European protected species such as roosting bats by monitoring bat activity and reducing unnecessary disturbance, and supporting the state of local biodiversity, both in terms of short-term impacts and long-term impacts. A method of ticking off catering to both of these considerations is through using bat surveys to find evidence of bats early on, utilising state of the art technology such as bat detectors, determining roosting features that could serve as suitable habitats for future species, mitigating against potential stumbling blocks in the planning process, and remaining in line with the expert guidance and support of the BCT and Natural England.
Bat Emergence Survey Season
As with any legally protected species surveys, bats are protected under certain legislation and restrictions are in place based on the specific bat activity, behaviours and hibernation patterns of the species in question. Due to this approach, the Bat Emergence Survey season will be undertaken outside of bat hibernation.
Bats generally hibernate between November and March, meaning that it is only possible to carry out BERS in a certain time of the year between the months of April and October. However, the optimal period lies in the summer months between May and September, with the provisions of the Bat Conservation Trust publication ‘Bat Surveys for Professional Ecologists Guidelines – Good Practice Guidelines’ insisting that Emergence Surveys are solely conducted within this time of the year.
Bat Emergence Survey Guidelines
Within full bat survey guidelines from the BCT, Emergence Surveys must be conducted solely around sunrise and sunset, more specifically – 15 minutes before or two hours after sunset, or two hours before or 15 minutes after sunrise. For this reason, Bat Emergence and Re-Entry Surveys are often also called Dusk and Dawn Surveys, Dusk and Dawn Re-Entry Surveys or Dawn and Dusk Emergence Surveys. Elsewhere, they may also be referred to as Bat Activity Surveys. Ecological consultants will monitor the area during several visits over numerous occasions until sufficient data on bats such as numbers, species, access points, roosting locations and roosting features has been collected.
The number of bat consultants required for the BERS and other factors will be determined by the results of the Preliminary Roost Assessment (PRA) / Scoping Bat Survey carried out beforehand. The PRA will also influence the number of visits to the site for an Emergence Survey, with the size of the site and the low or high suitability for bat roosts acting as the deciding factor on whether one, two or three surveys are required. Not only will this help to fully cover the area, but it will also ensure that every bat species has been accounted for, particularly if there is an extensive number.
Although the work methods and approach for Bat Activity Surveys may vary depending on the expert opinion of the ecologist carrying out the impact assessment, it often involves the same sorts of ecological survey equipment. Examples of this include bat detectors, infrared, night vision and thermal imaging cameras to see the present species of bat, and voice recorders that convert the bats’ echolocation calls into a tangible frequency readout. As each species has a different type of bat call, the ecologist can use this information as a secondary method of determining species.
During the course of Activity Surveys, if you find bats using your property or site as a roost, the focus is on collecting and indexing three primary types of data:
- What species of bat are present?
- What is the population (or best approximation with large numbers) of those species?
- What are they using your site for?
Once the collected data has answered these three questions, the results will dictate the mitigation measures in the survey report, and the chosen approach will vary significantly based on the certain circumstances. A single male soprano pipistrelle bat (Pipistrellus pygmaeus) using your barn as a transitionary summer roost, for example, will require very different mitigation measures to a maternity colony of the ultra-rare Barbastelle bats (Barbastella barbastellus). Fortunately, each licensed ecologist in our ranks possesses the necessary mitigation licence to implement effective changes that will protect bats while guaranteeing that their recommendations don’t obstruct access on the development site for the proposed work to go ahead as planned.
What is Bat Mitigation?
Bat mitigation is a simple process that revolves around preventing a loss of habitat and maintaining habitats present on the site. In the months between November and March, bats undergo a period of hibernation – a biological change that coincides with a drop in metabolism, a reduced heartbeat, consistently regulated temperature and utilisation of fats already in their system from past months. Known as torpor, hibernation is a form of suspended animation that will affect bats, leaving them extremely sensitive to disruption. So much so, in fact, that if someone were to disturb bat roosts during hibernation, it could even kill them.
As a result, implementing appropriate mitigation measures from the perspective of an ecologist with a bat mitigation class licence is often preferred outside of hibernation season. However, the restriction on time limits 12 months down to seven, potentially causing costly delays to developers that need their new development to progress straight away. Eliminating this issue is simply impossible, but you can plan ahead by booking a Bat Emergence and Re-Entry Survey with us as early as possible so we can arrange a visit to your site at the next available opportunity.
It is easy to assume that mitigation measures will be comprehensive, complicated and costly, but in fact, they are often easy to implement and relatively cheap. In far from rare cases of a single common pipistrelle (Pipistrellus pipistrellus), for instance, mitigation could be as simple as installing some bat boxes on your site as an alternative bat roosting location. Likewise, it could be just as effective to make use of innovative building products, like ‘bat access tiles’, that can be installed in a way that appeases inhabiting bats without making your property look unsightly.
Alternatively, however, bat mitigation can be far more complex. Larger species of bats protected by corresponding legislation, like brown long-eared bats (Plecotus auritus), for instance, are not crevice dwellers like their pipistrelle cousins. Instead, they require a void to make short flights that prepare their body for the strenuous nature of hunting flying insects, and need to elevate their heart rate and pump some blood into their wings before emerging from existing roosts they’re flying from or new roosts they’re flying to.
A suitable void can quite easily be a section of your roof void or loft space, partitioned off. That said, if it presents an issue, such as if you are planning a loft conversion, then other solutions that would better fit your development plans need to be considered, such as the example below:
Bat Emergence Survey Cost
Due to the fact that they involve multiple visits to the site, at night, during certain periods in the year and involving more than one bat surveyor to cover numerous angles, an Emergence Survey is more expensive than a PRA and other legally protected species surveys. On estimate, a BERS consisting of two to three days’ professional bat work will cost in the region of £789+VAT.
However, the specific circumstances of your site and project will affect the number of visits and professional ecologists required to conduct the assessment. For an accurate quote, it would be advisable to contact us, and our team can give you a price that reflects the direct specifications of your project.
Book a Bat Emergence Survey Today
With over a decade of experience carrying out Bat Emergence and Re-Entry Surveys and other bat assessments, our ecological consultancy services boast of a team full of experienced and qualified bat surveyors that are situated across the country, making it possible to visit your site regardless of where you are based.
With a thorough understanding of ecological surveys and the current good practice guidelines from the Bat Conservation Trust and Natural England, as well as general habitats regulations, our surveyors are registered in England and equipped to provide expert advice. It is important to note that they cannot override professional judgement or replace experience of other key stakeholders, but they are effective in conducting bat surveys to a high standard, and they can also comprehensively analyse both the project and the site to consider whether further surveys are required.
If you need more convincing that your project would be in good hands with us, simple check out our feedback and see the seemingly endless array of five-star reviews sent in from happy clients, past and present. You also don’t need to feel compelled to commit until you are satisfied with the service we offer, as we will provide you with a quote based on details of your site and project.
You can then mull over your quote, and if you decide to go ahead, simply get in touch with us to confirm that you wish to move forward with the process and we will be able to work with you to arrange a suitable date and time to visit your site and carry out the initial assessment, often regardless of weather conditions. Once the survey is complete, you will receive a comprehensive Bat Emergence Survey report a few days later, and it can support your application to the local planning authority for planning permission.