This is a complete guidance page to bat surveys and contains everything a development professional or domestic customer will ever need to know about how to deal with a request for a bat survey, and what the downstream implications are for your application and project. The video above is taken by Martin O’Connor, surveyor at Arbtech Consulting Limited, during a bat survey at a barn in Surrey, during the 2013 survey season, using our infra-red lighting and camera set up. It features a Brown Long Eared bat (Plecotus auritus).

Why am I being asked for a bat survey?

You have been asked for a bat survey because legally protected species and habitats that could be present and affected by your proposed development are a material consideration for your local planning authority. Since the planning officers do not have the resources to confirm whether or not legally protected species are present at your site, it becomes your responsibility to engage a bat surveyor and provide a report of their findings to support your planning application.

Various legislation makes it very clear that local authorities should refuse consent where this information is absent or inadequate, and should not under any circumstances leaves protected species surveys to conditions of consent.

What do you mean by ‘Protected’ species?

The EC Habitats Directive protects bats, like other species e.g. great crested newts through their inclusion in Annex II. This European protected species and habitats legislation is transposed in the UK by the Habitats Regulations 2010, which prevents bats as well as their roosting habitat from being disturbed. Bats are also protected by the Countryside and Rights of Way Act 2000 and the Wildlife and Countryside Act 1981, which criminalize deliberate killing, injury or sale.

Engaging the Directive is seriously hot water. Cheshire East council were criminally prosecuted and lost appeals all the way up to and including the Supreme Court for not properly enforcing legislation, let alone breaching it themselves. This has become known as the Woolley case. Needless to say, the successful prosecution (and other Supreme Court cases, such as Morge v Hampshire C.C.) has left planning officers very nervous about leaving protected species issues to conditions, so addressing such matters up front and robustly is the only way to secure a consent.

Who can do a bat survey?

Only a licensed bat consultant; someone who is educated and trained to handle and disturb bats safely (and has received a rabies vaccination!) can undertake your roost visit. A license is issued to a surveyor by Natural England in England (Natural Resource Wales; Wales, and Scottish Natural Heritage; Scotland.) These organizations are executive agencies of the UK government, so-called Statutory Nature Conservation Organizations.

The license essentially permits actions that would otherwise be unlawful e.g. disturbing bats. You should also ensure that your chosen consultant has Professional Indemnity insurance of at least £1m, as well as Employer’s Liability public and Products Liability of at least £500k.

Are bat surveys time-sensitive?

Bats hibernate throughout the winter as there are fewer invertebrates about, on which they predate. In consequence, the need to maintain a low body temperature and manage down their metabolism by roosting in a very stable environment—stable in terms of temperature, humidity, light and noise levels, vibration and airflow—drives their need to roost in trees and buildings.

In their state of torpor, they are extremely vulnerable and waking a bat could easily kill it instantly (or use up valuable calories, so depleting its fat reserves and literally starving it to death—not good!) The intense physiological change they must undergo to survive this is quite phenomenal, but equally, presents planning applicants with constraints: that is, some types of assessment cannot be conducted during the hibernation season.

So, while you can instruct your scoping bat survey (or ‘initial assessment’) to be undertaken any time of the year, the more detailed ‘emergence’ (or ‘phase 2’) bat surveys can only be undertaken when bats are active and can be observed without risk of disturbing them. In reality, this season of activity is determined by the climate. A cold, wet March or April may delay the bats coming out of hibernation.

Conversely, a warm or mild October and November may prolong their activity. Generally however, it is accepted by most planning authorities that bat surveys should not be undertaken outside of May through September inclusive, without extenuating circumstances that are catalogued and justified in your report.

Why are there two types of bat survey?

Your scoping survey is simply an exercise to either confirm there is no likelihood of bats being present and affected by the development, or to inform the survey effort and design of bat emergence surveys. It is important as it provides the opportunity to reduce your up front costs by potentially eliminating the need for further, more costly and intensive bat emergence surveys.

If during the initial assessment we find bats, evidence of their activity e.g. droppings or dead bat carcasses, or ‘features suitable for roosting’ your local authority will expect that you undertake bat emergence surveys. The purpose of this is to provide scientific evidence to support your mitigation proposals. You can see an infographic (flow chart) that takes you through the scoping survey process by following this link.

So what exactly is an emergence survey?

Bats have evolved to take advantage of the night. Bats can predate using echolocation (handy!) and avoid their own predators, as well as avoiding competing with other predators such as birds. Emerging from roosts in the evening (dusk) and returning to roost at first light (dawn) is the reason of then phase 2 surveys are called ‘nocturnal or dusk and dawn surveys.

Our surveyors use special devices called bat detectors in order to convert the bats’ calls—which are normally outside the range of human hearing—into a frequency we can not only hear, but also interpret. Bat detectors allow surveyors to discern between species and gather information about population numbers and the use of the site. Passing bats make a different sound to so-called feeding buzzes, for example.

What does a bat emergence survey entail and cost?

Emergence surveys require the elevations of your building to be simultaneously visible to the surveyors and so normally, even for small properties; the minimum number of surveyors is two. In a more complex example, such as an ‘L’ shaped building, it would be at least three surveyors. Standard practice is to undertake one to three dusk surveys, as a minimum, in order to provide a set of scientifically defensible results.

If you have an unusual site or set of circumstances, do not be surprised if you have to do more survey effort than this, or even a bit less. So, while emergence surveys can be fairly straightforward and cheap, it is common for them to cost upwards of five hundred to one thousand pounds – not exactly small change! If you would like to know more about bat mitigation and what comes next, then please continue reading at this blog post about bat licences and mitigation. Video credit: Arbtech Consulting Limited