Out for the count: an evening vigil with bat conservationists

Marbury Country Park, Cheshire A fold-out table is a hubbub of measurements, weights, wing patterns and ear shapes

The dog walkers regard us with suspicion. Perhaps they think we're ravers, assembled in the car park just before sunset. While admittedly there is a van loaded with speakers and kit, the only stimulants you'll find are coffee and cake. I've joined the South Lancashire Bat Group and friends who are monitoring rare Nathusius' pipistrelles in Marbury Country Park.

With the traps and acoustic lures set among the vegetation, we're sitting patiently in camping chairs along the nearby path, watching the sun cast an apricot glaze across the mere. The bats begin to throw some shapes once the colour drains from the day. They are frenetic while they feast, whirling around the tree tops. We see them through breaks in the canopy, gorging on the tiny insects that cloud around the oaks and alders at the lake's edge.