New sensor offers a window into the secret lives of Britain's rarest bats

Device makes it inexpensive to monitor sites previously too hazardous or difficult for volunteers to enter after dark

The secret lives of the UK's rarest bats could be revealed thanks to a new sensor that can record ultrasonic calls in dense woodland areas that have previously been difficult to reach.

For decades, acoustic monitoring has been done by bat detectors carried by experts reluctant to stray into woodland thickets during night-time walks. Now a new 60 sensor that can be left in woodlands for up to a fortnight, called AudioMoth, is giving researchers a richer insight into the lives of these elusive mammals after a successful pilot study.