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What You Need to Know about Bat Surveys for Planning

The increasing amount of development in the UK has had a huge impact on bat populations. All 18 native species of bat have been affected – population numbers have dropped dramatically over the last century due to habitat loss impacting bat roosts and feeding habitat.

As a result, relevant legislation has developed so that bats are fully protected. Bats are legally protected (along with other European protected species) under the Wildlife and Countryside Act 1981 (as amended) and the Conservation of Habitats and Species Regulations (2017), which make it an offence to deliberately kill or disturb bats, deliberately capture bats, damage or destroy their habitat or obstruct access to their resting places.

Anyone carrying out a building or development project which may affect bats must prove to the planning authority that all the required steps are being followed to avoid disturbing bats or a bats’ roost. If the presence of bats is identified on a development site, a local planning authority will require evidence of mitigation to allow for the bats.

However, if you do find bats it does not signal the end of your development proposals; you may be able to go ahead in certain circumstances providing that appropriate mitigation and compensation measures are put in place for the species of bat, population, and roost type. Often, a different approach may need to be taken to avoid disturbance to the bats. Local planning authorities differ in their requirements, so it’s advisable to find out what your specific planning department will ask for.

It’s important to get the required bat surveys completed before any work starts to put yourself in the best position with the information to hand. Discovering bats when work is underway could prove costly and time-consuming, and put you at risk of prosecution. Bear in mind that Natural England regards bat surveys as having a shelf life of under two seasons old.

This includes small maintenance works such as repointing walls, rewiring, and repairing doors and windows, and more major works such as maintaining chimneys, roof repairs and tree removal. Ideal environments for bats include agricultural buildings, often in rural communities close to the natural environment where they can forage for food.

Why are Bats Protected?

Bat populations across all 18 UK bat species have been in decline over the last 50-100 years due to increased development, resulting in the loss of their natural environment and habitat. In response to this, protection for bats has been increased via Schedule 2 of the Conservation of Habitats and Species Regulations 2017 and Section 9 of the Wildlife and Countryside Act 1981.

Bats are fully protected by UK and European legislation and harming bats is a criminal offence. Anyone seeking planning permission for schemes involving conversion modification or removal of buildings or sites involving trees or other potential roosting sites, has a legal obligation to avoid disturbing bats. It is illegal to:

• Deliberately kill injure or capture a bat.
• Deliberately disturb bats whether they are at roost or not.
• Damage, destroy or obstruct access to bat roosts.
• Possess or transport a bat, or any part of a bat, unless it has been legally acquired.
• Sell, barter or exchange bats or any part of a bat.

If bats are present on your development site, it doesn’t mean the end of your scheme. Despite finding bats, you may be able to proceed in certain circumstances if you can provide appropriate mitigation and compensation measures for the relevant species of bat and the loss of habitat.

If your building works could impact bats and you need a bat survey, be aware that local authorities differ in their requirements, so it’s important to find out what your local authority’s bat survey guidelines are. If your plans will affect bats, consulting a licenced ecologist in the first instance will help you progress your development proposal through the planning process.

What is a Bat Survey?

Bat surveys find out if there are bats present on a specific site or they may use it at certain times of the year. There are several types of bat survey: a Preliminary Roost Assessment (stage 1) which is carried out before the more detailed assessment; the Bat Emergence and Re-entry Survey (also known as an Activity Survey or Phase 2 Survey) and Hibernation Roost Surveys.

Bat surveys that may result in disturbance to a roost should be carried out by a licensed bat consultant; licences are issued by the statutory nature conservation organisations in England and Wales, Natural England and Natural Resources Wales and in Scotland, NatureScot.

How long is a bat survey valid for?

The length of time that a bat survey is valid for depends on the local planning authority, but all are valid for 12 months and they usually extend for up to 24 months. Natural England regards bat surveys as having a shelf life of under two seasons old.

What is a Bat Roost?

It is a feeding or resting place that can be in caves, tree cracks, lofts, barns, under weather boarding, on gable ends, ridge tiles or under loose or hanging tiles, which suit crevice dwelling species. Pre 1914 buildings are particularly suited to meet the requirements of roosting bats. A perfect bats roost site offers a safe place in which to hibernate and raise their young while having access to a food source – usually insects and water.

Bats and their roosts

Bats will relocate to different roosts over the course of a year as their requirements change, so several roosts may be occupied over a season. Types of roost include maternity roosts, day roosts, transitional roosts, feeding roosts, and hibernation roosts; each has different benefits, but they must all provide safety from predators, the correct temperature, humidity, and offer protection from noise, wind and light.

Bat Facts

• Bats are the only flying mammal.
• They have four long fingers and a thumb, connected by a thin layer of skin to form wings.
• All UK bats exclusively eat insects. These may be caught in flight and eaten on the wing or brought back to the roost to eat – while hanging upside down.
• 75% of UK bat sightings are of the common pipistrelle: this is also the smallest UK bat, having a wingspan of 22cm. They have a brown back with lighter colouring on their stomachs and dark faces.
• The largest UK bat is the Noctule bat, which has a 36cm wingspan. It has light brown fur and dark ears, wings and face.
• Bats will nestle in crevices or hang upside down to roost; as they cannot launch from an upright position, this enables them to release their grip and drop into a glide.
• Bats hibernate upside down between November and March, maintaining a constant body temperature and living off stored fat.
• Females gather in a maternity roost to give birth, usually to one pup a year.
• The lifespan of a bat varies from five years to several decades, depending on the species: common pipistrelles can live for 4-5 years.
• Bats have sensitive eyes and can see in monochrome to find prey undetected at night.
• They use echolocation to identify objects, producing sound waves from the nose or mouth at frequencies that are outside the human hearing range. The sound bounces off objects and back to the bat to help them navigate.

Bat Surveys for Planning Purposes – the Steps to Take:

1. A Preliminary Roost Assessment.
2. If required, a Bat Emergence and Re-entry Survey and/or a Hibernation Roost Survey.
3. Propose appropriate compensation and mitigation measures for bats in your planning application.
4. Submit an application and obtain planning permission.
5. If required, apply for a European Protected Species Licence.

Preliminary Roost Assessment (PRA) or Scoping Bat Survey (Stage 1)

PRAs involve an internal and external inspection of buildings and can be carried out by a bat surveyor at any time of year. The aim is to exclude the following three factors, which trigger further surveys:

1. The presence of bats.
2. Evidence of bat activity, such as feeding remains, bat droppings, urine stains, fragments of prey or dead bat carcasses.
3. Access to features suitable for roosting bats, graded from low to high.

If bats are present and using existing roosts in a building, or there are roost features or resting places that they could use, such as loose tiles in slate roofs, gaps in brickwork, roof voids, or the site is close to natural habitats in woodland, then you must propose mitigation or habitat gains for bats as part of your proposed development; your scheme would result in a net loss of habitat without such mitigation. Tree removal works may also require a bat survey if the trees offer roosting opportunities.

Bat Emergence and Re-Entry Surveys (BERS)

Carried out following a PRA survey, which has found evidence of bats being present, or roosting opportunities, this bat activity survey is the second phase and is a more detailed process. Experienced ecologists will visit the site and make a physical inspection in daylight hours.

They will monitor potential bat exit points and access points to record bats as they return from foraging areas, and gather data, using specialist equipment such as bat detectors, infrared lights, night vision, and thermal imaging cameras along with detectors that convert echolocation calls into an audible readout. The calls of different species of bat differ, so this can help with identification.

The findings and recommendations, along with details of the effect that the development proposals would have on the bats, form the basis of this further survey. Bat emergence surveys will also contain mitigation measures to enable the planning application to progress, along with details including the type of roost, species and bat numbers.

The number of bat surveyors and site visits required by bat emergence surveys depends on the results of a preliminary roost assessment; bat activity surveys typically involve two or three surveys at dusk and dawn.

Bat Survey Season

Bats hibernate in winter as there are fewer insects for them to feed on, so BERS (also known as dusk and dawn surveys) are carried out in the summer months, typically between May and September, as the sun rises or sets, when bats emerge from or return to a roost. They are undertaken 15 minutes before or two hours after sunset, or two hours before or 15 minutes after sunrise.

Some local planning authorities will accept surveys done in the sub-optimal weeks in April and between September and October, provided that weather conditions are suitable. High winds or heavy rain may cause bat activity surveys to be cancelled, so it’s a good plan to factor this in and book early.

Your planning application, supported by a Scoping Survey and/or Bat Emergence Survey report will enable you to secure planning permission for your proposed scheme. While it may be necessary in some circumstances to obtain a European Protected Species Licence (EPSL) for your application, it will not stop you from obtaining planning consent from your local planning authority.

Hibernation Roost Surveys

Also carried out following a PRA survey, Hibernation Roost Surveys may be required where a building has suitable features or conditions for winter hibernation. A Hibernation Roost Survey will entail two visits by licenced ecologists between December and February to inspect the building for hibernating bats.

These surveys have different timeframes and different requirements: static detectors may be deployed for longer periods to record any bat activity and the thermal conditions of the existing building. Buildings which might shelter hibernating bats include old and listed buildings, livestock buildings, barn conversions in rural communities and agricultural buildings.

EPSL Applications

If investigations reveal the presence of a bat roost and it needs to be disturbed, damaged, or destroyed as part of your development, protected species licences will be required from Natural England. This can take an average of six weeks.

Where roosts of low conservation value are found i.e., small population numbers of common species of bat, a new type of license is available in England – a Low Impact Bat Licence or a Bat Mitigation Class Licence. This is held by a registered consultant and obtaining this can be faster than a full EPSL.

Bat Mitigation Work

The bat surveys collate data to establish:

• The species of bat present
• The bat population
• How bats use the site

Having gathered the survey data, a professional ecologist can recommend appropriate mitigation measures in the bat survey report, with the aim of preventing habitat loss and maintaining existing habitats to support roosting bats.

Examples of simple mitigation measures to support bats might involve installing bat boxes on site to provide alternative roosts, or fitting bat access roof tiles. Bat boxes can be fitted to trees and buildings. Large bat species have more demanding requirements, for example, brown long-eared bats need a void in which they can practice making short flights, such as a sectioned-off roof void or loft.

There may also be timing implications, depending upon the bat roosts present, and a specific working method is likely to be required. The Bat Conservation Trust provides detailed guidance on bat-related matters, including breeding sites, suitable mitigation techniques and new roosts.

Where Bat Surveys are Less Likely to be Needed

Bats are less likely to be found in new development: man-made structures in urban areas surrounded by little green space, industrial buildings, prefabricated buildings built from sheet steel, small, cluttered roof spaces or dilapidated property which does not offer a stable environment in terms of temperature and light.

However, bats are very resourceful when it comes to finding roosting opportunities, and therefore, a bat survey may still be required.

Need to Undertake a Bat Survey?

If there’s a reasonable likelihood of bats on your proposed development and a full bat survey is required, you need to get in touch with a suitably qualified ecological consultancy. If you need a bat survey, a licensed ecologist holding a bat licence will be able to give you detailed best practice guidance, advising on the type of bat survey you need, further advice on relevant legislation such as habitats regulations and the bat survey season time frames.

If you require a bat survey, professional ecologists will also be able to provide advice about bat survey cost options. Getting in touch with an ecological consultancy early on is recommended to maximise the chances of your full planning application being approved the first time by your local planning authority, avoiding delays to your planned development and ensuring that you don’t harm bats.