Bat Surveys for the 2025 Season

Monday 20th October

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This season our recorded emergences have been from Daubenton’s bats and common pipistrelles, though rarer species were also observed such as brown long-eared bats. Across the season we recorded 76 emergences, all concentrated at just three of the sites we visited.

These surveys allow us to make sure bats, a protected species, are not harmed during construction or development projects. By understanding where bats are roosting and foraging, we can adapt our work to safeguard them and comply with legislation. It’s about striking the balance between progress and protecting the wildlife we share our environments with. The work has taken us to some truly unusual (and sometimes challenging) locations: surveying from rooftops, crouching quietly under bridges, and even building a makeshift platform out of fence panels to cross dense bramble.

In August, ecologist Hannah Yetman carried out a bat survey along 1km of the Wood Green Tunnel near Walthamstow, ahead of proposed maintenance works, involving damming and draining the New River to remove silt and asses the structure for any faults to be repaired.

The tunnel was accessed via boat and during the inspection, a maternity roost of approximately 30-35 Daubenton’s bats was identified beneath a manhole cover at the tunnel’s midpoint. A single bat was also recorded roosting on brickwork around 300m from the main roost.

Given the presence of the maternity roost, it was recommended that the works proceed under a non-licensed method statement, with Natural England notified. To minimise the risk of disturbing bats during sensitive periods, works will be scheduled for either autumn or spring, avoiding the maternity and hibernation seasons.

As autumn sets in and bats begin to hibernate, we’ll be busy analysing the season’s findings. But come spring, our surveyors will once again be listening for those ultrasonic chirps that signal the start of another bat season.

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