16 Dec The use of night vision aids on bat surveys
The use of Night Vision Aids (NVAs) on nocturnal bat survey has become more established in the UK in recent years, and with interim guidance[1] and forthcoming changes to bat survey guidelines, the use of NVAs will become more widespread.
At BSG Ecology, we have been using NVAs such as infra-red and thermal imaging cameras routinely on nocturnal bat surveys for many years. The following is a project example where we have applied NVAs in typical and non-typical ways to inform an effective mitigation strategy that will deliver benefits to our client and to bat conservation.
Hotel redevelopment project, Leicestershire
During fieldwork to inform a planning application for the redevelopment of a former stately home and associated outbuildings into a hotel, a large roost of 380 soprano pipistrelle bats was recorded roosting in the eaves of a two-storey stable block.
The proposed redevelopment works will require significant works near to the roost, and the room below / adjacent to the roost will be converted into a hotel bedroom. To help design effective mitigation to retain access to the roost, but also prevent potential conflict with future hotel guests from noise and smell and we needed to answer certain questions:
- How do the bats access the roost?
- Are the bats confined to the wall cavity and eaves of the building or do they also utilise the loft space?
- If they use the loft space, to what extent?
To answer these questions, the use of NVAs has been crucial. Externally, infra-red cameras confirmed the bat access points and numbers of bats present which will enable roost access to be retained. The footage below shows the bats emerging from the roost taken during June 2022.
Within the loft space, NVAs were used to inspect the roost area to see if any bats were present on several occasions during daytime in June and July 2022. It was clear that groups of bats, including adult female and their pups, were present in the lower areas of the loft. The use of a high-quality infra-red camera enabled us to observe the bats from a safe distance (8m) without causing disturbance to the bats; this is demonstrated by the naturalistic behaviour recorded on the footage (an example below), including social interactions and pups suckling. Without NVA’s we would not have been able to observe this behaviour within the roost.
The use of NVAs on this project has enabled a mitigation strategy to be developed and will provide a baseline for which future monitoring can be assessed against to test the effectiveness of the strategy.
The are numerous benefits of using NVAs on bat surveys They enable surveys in low-light situations to be completed accurately with robust evidence recorded on the numbers of bats present and their behaviour, which can be advantageous for both development and conservation-led projects.
For further information on our bat survey and assessment services please contact one of our offices.
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[1] https://cdn.bats.org.uk/uploads/pdf/Interim-guidance-note-on-NVAs-May-2022-FINAL.pdf?v=1653399882