Bat Surveys – Clearly Explained.

Bats and Bat Surveys

Most of our bat related enquiries are in connection with a planning application and are at the behest of the Local Planning Authority (LPA), or because an experienced Architect or Planning Consultant has anticipated an LPA request and decides to pre-empt in the hope that planning delays can be avoided.


There are a whole host of reasons why a local authority might request a bat survey. Invariably, barn conversions and alterations to an existing roof structure no matter how minor, will often trigger a requirement for a bat survey. Initially, this is usually for a ‘scoping survey’ to consider whether more targeted surveys are required. Occasionally, this initial survey is all that is required. Other times this is simply a precursor to Emergence Surveys.

So why do LPA’s insist on bat surveys?

The simply answer is that they do so in order to comply with legislation that places an obligation on LPA’s to consider the impact of any planning proposal on Protected Species. Obviously, they cannot comply if they do not know whether Protected Species are present on the site, or in close proximity to a site proposed for development. Therefore, the onus is on you to provide them with the information that they require, to determine whether an impact is likely or not.

Bats are only one group of animals that are defined as ‘Protected Species’, others include: reptiles, dormice, water voles, great crested newts (and some other amphibians), badgers and some invertebrates including white clawed crayfish and some moths and butterflies. Whilst the terminology might be a little different, Schedule 1 birds are also highly protected.

In addition to Protected Species, there are large number of organisms which fall into a category known as ‘Species of Principal Importance’. These were formally known as Biodiversity Action Plan (BAP) Species

There are various tiers of protection with some animals (and plants) protected under European legislation, whilst others are protected under UK legislation. Whilst the degree of protection accorded might vary under different legislation, in simple terms, to greater or lesser degrees, the potential impact upon a Protected Species and Species of Principal Importance must be taken into account by the LPA.

Bats fall under the highest tier of protection, which protects not just the animal, but also its habitat, roosts and resting places.

What types of Bat Survey might I require?

Bat and Nesting Bird Scoping Survey

Bat and Barn Owl Survey / Preliminary Roost Assessment / Phase 1 Bat Survey – They all amount to the same thing: A scoping survey to ascertain the presence / potential presence of bats and nesting birds.

If proposals involve works to a roof, or perhaps demolition of a structure (including trees), it is often necessary for a scoping survey to be conducted.

This type of surveys is intended as a physical survey of a site. It involves surveying the exterior of buildings, (and on occasion adjoining structures) looking for potential access points into the building for bats / birds. These could be broken tiles / slates or gaps behind fascia boards, gaps behind lead work, under ridge tiles or other holes/gaps.

An internal survey of the structure is undertaken to look for potential signs that the structure has been utilised by bats. These could be in the form of bats, droppings, prey remains and other signs too. In addition to the physical survey, desktop data surveys are also undertaken.

Assuming that no evidence is recorded and that no potential access points (that could not be fully investigated) exist, a report is generated for onward transmission to the LPA. In the majority of cases this is sufficient. However, the LPA are at liberty to request that further Emergence Surveys are undertaken irrespective of survey results.

What if Potential or Confirmed Roosts are recorded –

The purpose of ‘Phase 2 Bat Surveys’ is to ascertain with a degree of certainty whether a structure is being used by bats and if so, for what purpose. It produces the information required to apply to Natural England for European Protected Species Licences (EPSL) which are required if a roost is to be disturbed or destroyed.

Different types of roost and different bat species require different forms of mitigation (arrangements to ensure that neither individual bats, or bat roosts, suffer any adverse impact as a result of the planning proposals). Each EPSL is tailored to the exact requirements of the site.

Applications to Natural England for EPSL are dependent on planning permission being granted by the LPA. Therefore, once the report has been generated it should be submitted along with the planning application as part of the material consideration required towards protected species and the LPA will be unable to grant permission without being able to evidence that they themselves have complied with Protected Species legislation.

Emergence / Dawn re-entry Surveys

These surveys are usually undertaken if the bat and nesting bird scoping survey either found evidence of bat presence, or was unable to confirm absence due to features that might permit bat presence, but which for whatever reason could not be adequately surveyed e.g. slipped slates with roofing felt below, would permit entry into a gap between slates and roofing felt (the batten gap), which may leave little if any internal evidence.

Surveys are generally undertaken in the period June – August inclusive. Although, it might be possible to extended this to May to September inclusive. The actual level of survey required is determined by the ecologist who takes in to account various factors in making a determination.

Dawn emergence surveys require surveyors to observe areas of a structure from which bats might emerge at dusk, whilst dawn surveys observe bats re-entering a structure. Both are often required, although generally emergence surveys are undertaken initially. If there is some doubt over the actual entry/exit place of bat/s from the structure, dawn surveys often permit a clearer view, due to bats often repeatedly circling and landing prior to re-entering a structure. 


The number and form of surveys required is situational and contextual. The number of surveyors required is determined by the number of entry / exit points and size and shape of the building to be surveyed. This should be confirmed within your quotation.

Hibernation Surveys

Hibernation surveys are undertaken at structures which offer suitable hibernation potential. These are more akin to scoping surveys as the focus is on finding hibernating bats.

On occasion, additional surveys are required above and beyond the standard and this is especially so if particularly rare or unexpected species of bat are encountered.

Activity Surveys

Whilst roosts are protected by the measures discussed above, bat habitat, foraging, navigation and flyways are protected by ensuring that a full understanding of how bats are using habitat in areas proposed for development.

There are numerous methods recommended to ascertain how bats utilise habitat, but in summary it can be summarised by stating that both manual transact surveys and automated fixed location detector surveys are usually used. The format and design of surveys varies from site to site.

Please contact us for a site specific quotation –

Please call us on 0800 888 6846 / 07736 458609