Tree Climb and Inspect surveys for bats – why are we such fans?
LSC have three CS38 qualified ecologists who also hold Natural England bat licences which permit them to climb trees and inspect potential roost features (PRFs) for bats. We have been undertaking these surveys for over five years and have recorded inspections of thousands of trees in this timeframe. The traditional approach for surveying trees for bats is to conduct dusk and dawn emergence/re-entry surveys from the ground but ,whilst this still has its place, we think that the climb and inspect option has many advantages. Here are just a few:
Trees come in all shapes and sizes and inspecting a mature oak with many features can take half a day or more. On the other hand, we have climbed and comprehensively inspected 25 semi-mature trees in a single day before, but 8-10 trees a day is a good average to work on. Surveys of 16x trees would take a team of 2 surveyors a week of dusk/dawn surveys to assess, so it’s easy to see that deploying a pair of climbers to inspect these in two days would be much more efficient.
An inspection of a PRF at height allows the surveyor to fully understand a feature. Does it extend upwards, is it clean or dirty, does it even provide a roosting opportunity at all? From the ground, a good surveyor has to be precautionary and assume that an apparent feature might be a PRF – however from an aerial inspection, we frequently confirm that 50% or more of apparent PRF’s are in fact unsuitable for bats and can be ruled out. Conversely when the feature really is good with high potential for bats, we can identify this and grade the PRF accordingly.
When we get to a feature, we would search not only for live bats in residence, but for evidence which suggests they have been there recently. This includes a search for bat droppings, or for other tell-tale signs of recent occupation such as smoothing of the cavity. An aerial inspection can identify conclusive evidence which spans several nights, compared with the individual snapshot of the emergence survey which can only tell you if a bat was in residence on that occasion.
The climber who has inspected hundreds of PRF’s at height has a much better idea of how a feature viewed from the ground might look when they’re in up the tree. Climbing is a great opportunity to check and correct your assumptions and bring this knowledge to the next assessment you undertake. Our climbers have developed this experience over a wide range of projects and can use the knowledge to provide you with an expert ground-level assessment as well as a confident and efficient aerial inspection service.
We work extensively throughout the Midlands and the rest of the UK. In August of this year, our climbers have completed inspections in Warwickshire, Essex, Nottinghamshire and Derbyshire. For more information on our aerial inspection services, follow this link!