Bats

Bats

British Species and Ecology

There are a total of 17 species of bat resident in Britain plus a number of others that have only been recorded as occasional visitors to the UK

The majority of bats are active between April or May and October depending on the weather conditions. Bats roost in a wide range of locations; typical sites include trees with loose bark, holes and cracks and perhaps more commonly in buildings. Building roosts maybe in barns, older traditional style buildings and modern houses. Typical roost sites in buildings include roof spaces, soffit boxes, behind hanging tiles and under loose lead flashing. Bats may enter these roost spaces through very small gaps that may not be evident to the non-specialists.

Protection Under UK Legislation

In England, all bats are fully protected under the Wildlife and Countryside Act 1981, through inclusion in Schedule 5, and under the Conservation (Natural Habitats, &c.) Regulations 1994, which implements the EC Habitats Directive 92/43/EEC in the United Kingdom.

Taken together, these legislative instruments make it illegal to carry out the following activities:

Deliberately or recklessly capture or kill bats;
Deliberately or recklessly disturb bats;
Damage or destroy a bat breeding site or resting place; and
Keep, transport, sell or exchange, or offer for sale or exchange, any live or dead bat, or any part of, or anything derived from a bat.

Any activity that would result in a contravention of the above legislation would require a Natural England licence to avoid committing an offence.

Survey Methods

Bat surveys must be carried out by licenced surveyors, if there is a possibility of disturbing roosting bats. ECOSA surveyors hold current Natural England bat licences for England and Wales. Survey methods for bats consist of two phases, which apply to both trees and buildings:

Phase I

Phase I surveys consist of an evaluation of the structure of a building or features of a tree to determine their suitability for roosting bats. For example features such as loose bark on trees or gaps between tiles may provide roosting opportunities for bats. Phase I surveys will often need to be followed by Phase II surveys if evidence of roosting bats or features suitable for roosting bats are recorded or identified.

Phase II

Phase II surveys involve a detailed assessment of the status of a roost site or potential roost site. If the Phase I survey confirm the presence of a bat roost then Phase II surveys will be essential in providing sufficient information for a Natural England licence. Phase II surveys will usually involve the use of bat detectors to determine the species present within a roost, these are combined with counts. This accurate assessment is essential for bat licencing purposes. ECOSA use Pettersson 240x time-expansion detectors which slow down the echolocation made by bats (usually by 10x). This enables a recording to be made which can be downloaded into analysing software. Once the recording is opened within the software it is displayed as a sonogram and from this it is possible to analyse parameters of the echolocation such as its peak frequency, duration and time between calls allowing species identification.

Survey Timing

Phase I surveys can be carried out throughout the year, but will almost invariably lead to Phase II surveys which are carried out between late May and early September. At this time bats occupy summer roost sites and the status of a roost can be reliably assessed.

Mitigation

Mitigation for the loss of a bat roost is a requirement of a Natural England licence. The amount and type of mitigation for the loss of a bat roost will be dependant on the status of the roost. For smaller low status roosts the provision of bat boxes in trees or on buildings or the provision of bat roosting units in buildings may be sufficient. For higher status roosts such as maternity roosts the construction of dedicated bat roosts may be necessary. ECOSA has a wide experience in advising on and implementing suitable mitigation strategies.

Links

Bat Conservation Trust

Bat Ecology & Bioacoustics

Disclaimer

Although we have taken great care to ensure that our information and advice is correct, we cannot accept any responsibility for any incorrect information, loss or damage incurred arising from the use of the information published on our web site. For further advice, detailed surveys and quotations please contact ECOSA.

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