A dozen of us joined Mark Langley from Monmouthshire Countryside Services for a dusk walk around the Meadows to look and listen for bats. First stop was the river, but there was too much wind to spot the Daubenton’s bats that can sometimes be seen skimming low over the water in search of insects. We had better luck by the copse where there were plenty of pipistrelles flying around. Mark’s bat detectors brought their calls down to human hearing range, so we could listen to them both navigating and hunting for small insects using high-frequency sound. Working out whether their squeaks were loudest at 45kHz (common pipistrelle) or 55 kHz (soprano) kept us happily – and inconclusively – occupied till well after dark.