11 Sep Trapping and Radio Tracking of Bats to inform Mitigation and Licencing.
We have recently captured and tracked bats to inform mitigation for impacts on woodland in north-eastern England. This short article outlines why these methods were necessary and how the results will benefit our client.
Survey was required to determine whether an area of woodland that will be unavoidably reduced in size as a result of development supported bats. A guidance-led programme of work was initially implemented (in 2018), which began with ground based assessment and included the use of static detectors, transects and climbed surveys to identify the potential for bats to roost within the wood. As a result of the survey work it was established that a range of bat species were present, some of which were roosting. The function of the woodland remained unclear however: what was the nature of these roosts, were some bats commuting in to the woodland to forage, and what was the value of the woodland resource to bats in assessment terms?
Having reflected on the initial results and discussed their limitations with our client, we teamed up with Corylus Ecology in 2019 to undertake a programme of mist netting and harp trapping that would address the unanswered questions. Sixty-seven bats of six species were captured, a proportion of which were then tagged and radio tracked. The tracking exercise resulted in the identification of six previously unknown roosts in the local area (but not within the woodland), and showed that bats both visited the woodland to forage and ranged along river catchments and over other semi-natural habitats in the wider area. While no maternity roosts were located in the wood, the trapping confirmed that non-breeding, breeding and juvenile males, post-breeding and juvenile female animals were foraging within it. Currently, work is being completed to determine whether the woodland is also used as a mating area.
As a result of the work we are now able to complete a more robust ecological impact assessment, deliver more focused mitigation and have a suitable evidence base for European Protected Species licencing. This will allow our client to move forward with their project.
BSG Ecology is regularly involved in the radio tracking of bats, and is currently conducting research on the Blenheim Estate (Oxfordshire) as well as other private contracts that require it. To understand the full range of bat survey and assessment services we offer see our Bats and Tree Survey for Bats service pages, or contact one of our offices.
Top image: Senior Ecologist Hannah Norman with Noctule bat