Plecotus auritus - Brown long-eared bat

There are over 1,400 species of bat worldwide, 18 of which reside in the UK. They are the only mammal capable of ‘true flight’ and account for 25% of all British mammals. They are incredibly important to the environment and perform a variety of eco-system services including pollination and the control of insect populations. Bats have few natural predators and habitat loss is one of their main threats, which is why it is crucial to consider them in any development proposals.

The terrestrial ecologists at APEM regularly conduct assessments of bat roosts, but what exactly is a bat roost and where can they be found? And importantly, why should you consider them in your project?

Bat ecology

Any place where a bat rests, raises young or hibernates, is considered a bat roost. Bat roosts can be found in natural structures such as in trees and caves, but they can also be found in a variety of man-made structures such as barns, houses, bridges, and office blocks.

Bats have different requirements for roost locations depending on changes to their behaviour at different times of year.

While it does vary from species to species, generally in the summer months bats require warm dry places for rearing their young (such as loft spaces), whereas in the winter bats require cool, damp conditions for hibernating (such as caves or bridges).

All British bats are classed as insectivores, which means they exclusively feed on insects. They navigate the night by using echolocation, where they produce and project sounds onto potential prey. The returning echoes then relay information to the bat about the prey, such as the size and shape, and most importantly, where exactly it is!

Some species have evolved their own specialist feeding techniques, for example, Daubenton’s bats (Myotis daubentonii) have extra-large feet for picking up (or gleaning) insects from the surface of water bodies.

How are bats protected?

Bats are protected under both the Wildlife and Countryside Act, 1981 (as amended) and Conservation of Habitat and Species Regulations, 2017 (as amended). Together, these make it an offence to:

  • Deliberately take, injure or kill a wild bat
  • Intentionally or recklessly disturb a bat in its roost or deliberately disturb a group of bats
  • Damage or destroy a place used by bats for breeding or resting (roosts) (even if bats are not occupying the roost at the time)
  • Possess or advertise/ sell/ exchange a bat of a species found in the wild in the EU (dead or alive) or any part of a bat
  • Intentionally or recklessly obstruct access to a bat roost
Greater horshoe bat

Greater horseshoe bat

Protecting bats from development

It is because of this legislation that bats must be a material consideration when it comes to development, to ensure that the project will not have any detrimental impacts on the favourable conservation status of British bats. Damage, disturbance, and destruction of bat roosts is considered a criminal offence and can incur large fines and even prison sentences.

To avoid breaches in legislation, bat surveys by a suitably experienced, and in some cases licenced ecologist, may be required. Bat surveys can be broadly categorised into Stage 1 and Stage 2 surveys and will provide you with all the necessary information on how your project can avoid adversely impacting bat populations.

For buildings and other man-made structures, Stage 1 surveys usually encompass a Preliminary Roost Assessment (PRA), whereas a Ground Level Tree Assessment (GLTA) is used for trees. These surveys can be conducted at any time of year, although preferably in the winter months for a GLTA.

The aim of these survey types is to determine the presence or potential presence of bats and the requirement for Stage 2 surveys. If it has not been possible to completely rule out the presence of bats during the PRA, Stage 2 surveys are usually recommended.

Stage 2 surveys involve a more detailed assessment of the structure/tree and must be conducted in the bat ‘active’ season, which extends from May-August (this period can be extended into later months depending on the value of the site).

Once all the necessary Stage 1 and Stage 2 (where required) bat surveys have been completed, an ecologist will be able to determine whether your project is likely to adversely impacts bats.

If adverse impacts are likely, a European Protected Species Licence (EPS) may be required from the relevant Statutory Nature Conservation Organisation (SNCO; such as Natural England or Natural Resources Wales) which allows you to legally disturb or destroy the bat roost.

APEM have licenced bat surveyors with the necessary skills and qualifications to successfully deliver all Stage 1 and Stage 2 bat surveys for your project. Our surveys are carried out using best practice methods, and in compliance with industry guidance issued or endorsed by the relevant SNCO.

After all the relevant information is available it is evaluated and assessed for likely impacts on the protected species, APEM consultants can prepare survey reports and licence applications, mitigation proposals and/or method statements.

We can also provide an Ecological Clerk of Works (ECoW) and post-consent monitoring for protected species, if required.

Further information

For further information on bats or bat surveys, visit the following websites or contact us for further advice and guidance.

IMAGE CREDIT – Plecotus auritus – Brown long-eared bat –  Nils Bouillard

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APEM are a global environmental consultancy providing independent advice and guidance to support government and environmental regulatory guidelines.