Bat Surveys

There are 17 Species of bat native to the UK.  All species and their resting places are legally protected under both the Regulation 41 of The Conservation of Habitats and Species Regulations 2010 and Section 9 of the Wildlife and Countryside Act 1981. It is an offence for anyone intentionally to kill, injure or handle a bat, to possess a bat (whether live or dead), disturb a roosting bat, or sell or offer a bat for sale without a licence. It is also an offence to damage, destroy or obstruct access to any place used by bats for shelter, whether they are present or not.

Bats will use a variety of places to roost including, trees, caves and all manner of buildings and individual species have specialised to forage in a variety of most British habitats.

Bat risk assessments or scoping surveys can be carried out at anytime of year although they are most effective in the summer. These surveys are usually the minimum required by Local Planning Authority for any project affecting buildings or mature trees requiring planning permission.  In order to avoid contravening the Conservation and Habitat Regulations 2010 we recommend that a bat risk assessment is carried out prior to any activity that has the potential to affect bat roosts regardless of whether the activity requires planning permission (roof replacement, demolition, tree removal).

Bat risk assessments are specifically designed to look for suitable bat roosting habitat on any site. The assessment will usually include an internal inspection of suitable voids such as lofts. Habitat features will be rated on their potential to support bats following accepted methodologies as included within “Bat Surveys.  Good Practice Guidelines.” (BCT, 2007). Recommendations will be made accordingly.

Nocturnal Bat activity surveys can only be undertaken between May and September (inclusive), with surveys specifically targeting maternity colonies between May and August (inclusive). The surveys are carried out on buildings that have been found to have shown potential for or signs of bat occupation during the bat risk assessment / scoping survey. Nocturnal surveys are usually specifically targeted to establish three key aims.

• Presence/absence of bat roosts within the targeted structure
• Species and numbers of bats using the targeted structure (if bats present
• Type of usage of the targeted structure (if bats present)

This information will gathered of over a number nights usually requires the use for more than one surveyor in order to cover all aspects of the targeted structure.  Surveyors will be equipped with recording bat detectors (Anabat SD1 and Bat box Duets) and where relevant night vision equipment in order to accurately record activity associated with the targeted structure. The recorded data will then be analysed and used to inform a survey report that will include suitable site specific recommendations including whether a European Protected Species Licence is required for the development to continue.

Transect surveys are used to establishing a baseline for Bat activity over a wide area.  They can also help trace locations of roosts but cannot determine numbers of bats or the definitive species using a specific roost.

Transect surveys are particularly important for developments that affect a wide area of suitable foraging or commuting habitat (wind farms, large scale housing projects, quarries, road projects, etc.).  Such projects, as well as having a direct affect on bat roosts within their development area, could also have a significant negative effect on the survivability of roosts outside of their direct area of affect due to habitat degradation.  

Surveyors will be equipped with recording bat detectors (Anabat SD1 and Bat box Duets) and where relevant night vision equipment in order to accurately record bat activity as they walk or drive a set route through the targeted area. The results of these surveys will then be used to form an activity map for the site highlighting features of particular importance for bat species. This information will than be compiled into a report along with relevant site specific recommendations.

Bats will use a variety of structures in which to hibernate (cellars, caves, tunnels, bunkers and dead trees etc). Hibernation surveys can only be undertaken between October to March inclusive. The exact timing of the surveys will vary with weather conditions as some bat species will remain active if the temperature remains high enough. Surveys are likely be conducted using two methodologies; daytime roost searches and remote Anabat surveys. Daytime roost searches can be conducted throughout the Hibernation period, but are best conducted during periods of sustained cold weather. Remote Anabat surveys are best conducted during periods of transition in temperature (cold to warm or warm to cold).

If trees suitable for bats are to be affected by proposed works the most effective way of confirming the presence or absence of bat roosts within them is by aerial inspection.

Trees will be climbed using appropriate equipment following the Arboricultural Association’s (2006) and the Health & Safety Executive’s (2011; 2011a) guidelines for climbing trees. The inspection will focus on searching for evidence of bat occupation within suitable roost features. Where cavities are too deep or restricted to be directly observed an endoscope will be used. Should evidence be found the tree will be tagged as a bat roost.

The results of the surveys will be compiled into a tree assessment report along with relevant site specific recommendations.

Any project where bats may be impacted detrimentally will require a Natural England development licence to mitigate these affects on the population. Access Ecology has a number of Licenced and experienced staff who have compiled and managed successful licence applications for a range of differing development (and non-development) situations. As a result we are able to offer advice and expertise on all stages of the mitigation process.

We are also able to offer advice on the enhancement of sites for bats, this is becoming particularly important with Local Planning Authorities following Guidance for Public Authorities on Implementing the Biodiversity Duty (Defra, 2006) states,

“It is important that public authorities seek not only to protect important habitats and species, but actively seek opportunities to enhance biodiversity through development proposals, where appropriate. Incorporating enhancement opportunities into projects may help applicants to achieve planning permission”