Bat Survey

ABST surveys involve the temporary capture of Bats on-site through the use of mist nets and harp traps. Capturing bats in this manner enables the bat to be examined in hand for the purpose of confirming the species, sex, reproductive status and age. Depending on the scope of the project, in some instances, it may be necessary for captured bats to be fitted with a radio tag. 

This allows individuals to be tracked across the landscape to their roosts, foraging grounds and to pin­ point their flight routes. The use of ABST is an efficient way to provide robust, detailed and accurate survey data to support planning applications, inform European Protected Species Mitigation Licences (EPSML) and to tailor mitigation/ habitat creation and enhancement measures, increasing the likelihood that these will be correctly sited and effective.

ABST Survey should be considered when it is necessary to confirm Bat roost locations in woodlands and/or to confirm if cryptic species (those that are difficult to identify using sonogram e.g.) are present on-site:

• Myotis spp. or Barbastelle) are present on-site 
• To determine how Bats are utilising a site (roosting, commuting and foraging) 
• To assess the home range of Bats 
• To confirm/negate likely severance impacts 
• To determine whether Bats from a roost are also using an alternative roost within their range 
• To inform the appropriate siting of replacement roosts (optimising the likelihood of their colonisation) 
• To inform the locations of woodland planting corridors/other green infrastructure.

The use of ABST presents a number of advantages to the client over standard Bat survey methods. They can often provide a more cost effective and efficient approach to the gathering of data, particularly when complex mitigation measures are required involving multiple Bat species.

Furthermore, when providing alternative Roost sites, depending on the rarity of the Bat species using the Roost, and the type of Roost to be lost, proof of occupation (prior to the removal of any existing Roost) is sometimes required. This can result in costly delays to a scheme. A thorough understanding of flight paths, foraging areas and Roost requirements facilitates the design of appropriately sited, species specific mitigation measures, that are more likely to be colonised quickly by the resident Bat population.

The use of radio tracking as a survey methodology can also provide cost savings to the client, on the basis that the level of manpower required to gather sufficient evidence to inform large or complex schemes, is often reduced. Following trapping, Bats can be tracked to Roosts for up to tens days, when the tag is active. This approach can capture the usage of multiple Roosts by an individual/colony of Bats. In addition, the used of triangulation methods enables surveyors to cover greater distances within the tracking period of up to 10 square kilometres.

The use of ABST is also beneficial when detailed survey data is required for high impact or contentious schemes, or when there is the risk that the scheme might be subject to a public enquiry.

A high proportion of our Three Shires Ecological staff are licensed to handle Bats and use Endoscopes to investigate potential roosts.  Some hold enhanced licences allowing them to use of acoustic lures and capture bats in mist nets and harp traps.  These latter methods are increasingly required by local authorities when determining impacts of development on species of bats, such as Bechstein’s Bat, which cannot be determined by their call characteristics. One member of staff is also a Registered Consultant with Natural England, which permits them to use the Low Impact Bat Class Licence at registered sites. A few staff are also accredited to climb trees to inspect potential roost sites.

Our in-house team is complemented by regionally-based specialist sub-consultants, with whom we have long-standing relationships. This capacity and capability allows us to undertake bat survey work anywhere in the UK and Ireland to a high technical standard and enables us to deploy large teams of skilled field workers in a cost-effective manner.Our bat survey and data analysis capability includes:

• Designing and undertaking walked transect surveys;
• Remote survey using static bat data loggers (such as SM2 and Anabat detectors);
• Building inspections:
  • Assessment of the potential of building features to support bats
  • Inspection of internal roof spaces and other voids for roosting bats
  • Activity surveys (dawn and dusk surveys) to record bats emerging from or returning to roosts
  • Collection of droppings for DNA analysis to confirm species where appropriate
• A comprehensive bat survey service for wind farm schemes, including at height survey;
• Call analysis using a variety of specialist software;
• Tree surveys, including at height inspections by licensed surveyors and use of thermal imaging and infra-red equipment where appropriate;
• Survey and assessment of underground sites/tunnels for hibernating bats;
• Mist netting surveys to establish presence of species which cannot be confirmed from call analysis, including Bechstein’s bat, and to inform impact assessment;
• Radio tracking studies to establish habitat preferences and ranging behaviour of bat species.