British Standard BS 8596:2015 – Surveying for Bats in Trees and Woodland

British Standard BS 8596:2015 – Surveying for Bats in Trees and Woodland

British Standard (BS) 8596, which was published in October 2015, sets out guidance for surveying bats in trees and woodland.  This BS is relevant to both development and conservation-led work affecting trees and woodland habitats.

Since all UK bats and their roosts are protected by law (through the Habitats Regulations¹ and the Wildlife and Countryside Act 1981 [as amended]), the legal requirement to avoid killing, injuring or disturbing bats, or damaging or destroying their roosts is an important consideration for those involved in woodland and tree management.

BS 8596 sets out how surveys should be planned and carried out where work is proposed which has potential to affect bats in trees or woodland.

In this article we provide a review of BS 8956. In our view, the guidance provides some helpful clarification; however, care needs to be taken when applying the guidance. Surveying trees for bats is complex, and any non-specialist surveyors tasked with carrying out survey work need to have a clear understanding of when to seek advice from an experienced, specialist surveyor.

Aims of the guidance

The stated aim of BS 8596 is to bring together guidance on surveying for bats in trees and woodland, and to make it available to a variety of audiences (woodland managers, arborists, planning officers, developers, ecological consultants, and others). It refers to a range of operations from the management of trees and the loss of woodland as a result of development, to ongoing woodland and forestry management.  The standard seeks to set out a consistent approach to survey and assessment for bats; it also describes more advanced survey techniques that may need to be applied.

The survey process

BS 8596 describes a process for scoping survey requirements and undertaking bat roost and activity surveys. The guidance varies where tree or woodland loss is required as a result of development, or where ongoing forestry management is proposed².

To accommodate these varied applications, BS 8596 outlines which elements of survey can be carried out by whom, depending on experience, training and licences held. It describes situations when a non-specialist survey is likely to be adequate (i.e. a survey carried out by arborists and forestry workers with basic bat awareness training, as defined in the BS), and those where specialist surveys (those carried out by a professional ecologist/licenced bat worker) will be required.

The distinction between specialist and non-specialist surveyors is significant, since confidently identifying or ruling out the presence of bat roosts can be difficult, requiring experience in assessing potential roost features (PRF) and bat ecology, and a sound grasp of survey techniques and their effective application, including aerial tree survey (a PRF inspection survey).

If BS 8596 is widely adopted will it benefit bats?

The process of roost assessment and survey as outlined in BS 8596 establishes an approach which can be broadly adopted by those involved in tree and woodland management and it is likely to be used as an industry standard, certainly by the professional tree management industry (in a similar way to BS 5837³). Other related guidance also exists (including the forthcoming Bat Conservation Trust survey guidelines, due for publication in early 2016).

Without clear, accessible guidance there is a risk that the possible presence of bats (and associated risk) is not adequately considered or understood.  The requirement to carry out an assessment (and to maintain documented evidence), as set out in BS 8596, should in theory improve consideration of bats when tree work or woodland management is planned. By following the approach in the standard, those involved in tree work are likely to reduce their exposure to the risk (of both harming bats and of committing an offence).

The staged process of assessment, which makes use of non-specialist surveyors, makes some sense as it would not be practical (or realistic) for a licenced bat worker to survey every tree with cavities before any tree work or woodland management is carried out. BS 8596 does, however, place a great deal of reliance on the ability of non-specialist surveyors (e.g. arborists with bat awareness training) to identify potential roosts or rule out their presence. Ruling out roosts, or determining what level of follow up survey is reasonable, could make for a difficult decision for an inexperienced (non-specialist) surveyor. This creates a risk that roosts may be misidentified or missed due to the lack of surveyor experience and, therefore, non-specialist surveyors tasked with carrying out surveys do need to have a good, honest appreciation of the limitations of their experience and the various survey techniques involved, and significantly, to know when to seek advice from an experienced licenced surveyor.

A “micro-guide”, which is also available from BSI, and free to download, sets out some of the basic principles from BS 8596, and is designed for non-development related tree and woodland management.

BSG Ecology – Specialist bat advice and survey

BSG Ecology has an experienced team of consultants who are qualified to climb trees and licenced to carry out survey work for bats. We have carried out aerial inspections on many hundreds of trees throughout the UK since we first started to deliver this service in 2007. We also have a wide range of bat mitigation and (European Protected Species) licencing experience and provide training on bat survey work.


¹ In full: the Conservation of Species and Habitats Regulations (2010), as amended).

² Guidance on implementing the Habitats Regulations differs slightly between development, which is subject to a consenting process, and ‘ongoing activities’ such as agriculture and commercial forestry which are not, although the same strict protection applies in both cases (European Commission: Guidance document on the strict protection of animal species of Community interest under the Habitats Directive 92/43/EEC (February 2007): 30-35)

³ BS 5837:2012 Trees in relation to design, demolition and construction – Recommendations

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