Types of Bat survey
Initial Bat Barn Owl and Nesting Bird Surveys (Bat and Barn Owl Survey)
Initial Bat Barn Owl and Nesting Bird Surveys (Bat and Barn Owl Survey)
Initial Bat Barn Owl and Nesting Bird Surveys (Bat and Barn Owl Survey)
When planning work which has the potential to impact the parts of buildings used by bats or nesting birds- most commonly the roof spaces and eaves of a building- it is advisable to have an initial Bat, Barn Owl and Nesting Bird survey undertaken (BBONB).
This type of survey is frequently required by the planning authorities to inform their planning decisions for extensions, roof maintenance, demolition works and work that may impact the roof or external structures of occupied or unoccupied buildings and agricultural barns.
This type of survey can be undertaken at any time of year and involves a careful inspection of the building, both internally and externally, looking for signs of use by bats and for features with potential for use and includes an assessment for nesting birds, including Barn Owls.
Preliminary Ground Level Roost Assessment
Initial Bat Barn Owl and Nesting Bird Surveys (Bat and Barn Owl Survey)
Initial Bat Barn Owl and Nesting Bird Surveys (Bat and Barn Owl Survey)
Most species of bat traditionally use features in trees for roosting. These roosts can be impacted by the pruning or removal of the tree, the construction of buildings nearby or through the introduction of artificial light in the vicinity of the tree
If trees are at risk of being impacted by a development a Preliminary Ground Level Roost Assessment may be needed either to support a planning application or to inform the works.
This involves carrying out an inspection of the tree from the ground using a high power torch. Tree roost assessments are best conducted in the winter when the trees are without their leaves and involves identifying and assessing features on the tree that have the potential to support roosting bats.
Potential Roosting Feature Assessment
Initial Bat Barn Owl and Nesting Bird Surveys (Bat and Barn Owl Survey)
Potential Roosting Feature Assessment
If Potential Roosting Features are observed on a tree during the Ground Level Roost Assessment then a Potential Roosting Feature (PRF) assessment is likely to be necessary to assess the features identified and establish the presence or absence of bats. If these features are accessible from a ladder this will be carried out at the same time as the Ground Level Roost Assessment.
This assessment involves inspecting the features identified as having the potential to be used by roosting bats using a torch, or endoscope to assess in more detail their likely suitability for use by bats and to look for evidence of use including the presence of individual bats, droppings, staining, odour, the presence of parasites.
This inspection also aims to identify any additional potential roosting features not observed during the ground level assessment which may provide roosting space for bats.
Bat Emergence/Re-entry surveys
Bat Development Mitigation Licences
Potential Roosting Feature Assessment
If evidence is found of the use of a building by roosting bats or features with the potential to be used by roosting bats are identified during a Bat, Barn Owl and Nesting Bird survey, it is likely further survey work will need to be undertaken.
This usually involves carrying out evening emergence/dawn re-entry surveys which involve the positioning of surveyors around the building being surveyed, from just before sunset/sunrise until 1 to 2 hours afterwards/before to watch for emerging/re-entering bats. Theses surveys aim to determine if bats are roosting in the building, and if so, the species, the status of the roost, the number of individuals, the roosting sites and access points.
This information is then be used to assess the potential impacts, if and how they can be avoided, what mitigation is needed and if a Bat Mitigation Licence will be needed to cover the works.
Bat Activity Transects
Bat Development Mitigation Licences
Bat Development Mitigation Licences
Where development of an area of land could result in the degradation or loss of bat foraging habitat which could adversely impact bats, further survey work is likely to be required to establish the level of use of the site, the species present and the likely impacts. This information can then be used to inform mitigation to safeguard important flight lines or areas of habitat.
The need for this type of survey is usually identified during a Preliminary Ecological Appraisal and consists of a set of three or more (dependent on the value of the site) walked activity transects, walked at dusk/dawn, paired with the deployment of a static bat detector.
Bat Development Mitigation Licences
Bat Development Mitigation Licences
Bat Development Mitigation Licences
If works to a building, in which bats have been found to roost cannot be undertaken without negatively impacting the bats it is likely that a Bat Mitigation Development Licence will need to be obtained from Natural England before the works can proceed lawfully.
This will involve timing the works to be carried out when bats are least vulnerable to disturbance, carrying out the works carefully to ensure bats are not harmed and installing mitigation to allow the bats to continue living onsite, ideally using the same roosting sites.
We have vast experience designing mitigation, obtaining Bat Mitigation Development Licences, and supporting clients and contractors through the process and with its implementation.
We have successfully obtained Full Bat Mitigation Development Licences for a wide range of bat species, including rare species, and Simon is a registered Consultant on Annexes B, C and D of the simplified Bat Mitigation Class Licence for small numbers of common species of bat
What to expect from a bat survey
What to expect from a bat survey
What to expect from a bat survey
If you are unsure whether you need a survey please feel free to contact us. Or, if you would prefer, please follow the above link to the CIEEM website for free advice on what to expect from your survey and what may happen as a result of instructing a bat survey on your property or for your project.
Survey Methods and Techniques
Observation and passive listening
Observation and passive listening
Observation and passive listening
During dusk and dawn emergence/re-entry surveys and Bat Activity Transects bat detectors are an important tool. They allow us to listen to the bats whilst we observe where bats are either coming out from, or entering the buildings, or flying around a site. They also assist with identifying which species are being observed.
Observing where bats are coming from during emergence/re-entry surveys becomes more difficult when surveying for late emerging or early re-entry bats and this is when the use of aids such as Thermal Imaging and night vision equipment becomes important.
Thermal Imaging
Observation and passive listening
Observation and passive listening
Thermal Imaging devices are an important tool as they allow the locations of roosts and access points to be identified in the lowest light conditions and late after they would otherwise be missed.
Our ecologists are fully trained in the use of Thermal Imaging devices and how best to operate them for optimal viewing to help pinpoint where bats were accessing buildings or trees. We still use bat detectors in conjunction with the Thermal Imagine devices to identify the bats to species level.
Infra red video
Observation and passive listening
Mist netting and Harp trapping
Infra-red cameras are another important tool to assist with identifying the roosting and access points used by bats on trees and buildings.
This is more widely used than Thermal Imaging as it is much lower cost and makes use of infra red light to help illuminate bats in the dark. This helps our ecologists pinpoint where bats are accessing buildings or trees and combined with the use of a bat detector to identify the bat to species level.
Mist netting and Harp trapping
Remote detecting sound analysis
Mist netting and Harp trapping
Passive listening and watching bats can not always gather enough data regarding a site or project sometimes it is necessary to catch bats. Simon is licensed to carry out Mist netting and Harp trapping which can be used to gain a better understanding of the local populations of bats, how they make use of the landscape and can be used to identify the presence of cryptic species which are difficult to differentiate using bat detectors alone.
Remote detecting sound analysis
Remote detecting sound analysis
Remote detecting sound analysis
Part of most bat survey work, involving either buildings or sites, will involve the deployment of a remote or static bat detector into the building or site being surveyed. These detectors record all bat calls emitted within its range and then with this information calls can be analyzed to determine the frequency of activity, the species of bat it is associated with and the timing of any peaks in the activity recorded.
The reason for using these detectors to supplement the manned surveys is because these detectors remain in place for a number of nights sampling bat activity over the full night and provides valuable additional information.
Trail camera trapping
Remote detecting sound analysis
Remote detecting sound analysis
Our mammal surveys, including bats, can also involve the use of static wildlife trail cameras which are triggered by movement. These cameras can help record activity around a site, e.g. near Badger Setts or important habitat features which would otherwise be disturbed by the noise and presence of a surveyor when the animals are likely to be active.
The appropriate use of these cameras can also help reduce the need and costs of a surveyor needing to be present or the regularity of the visits needed.