Bat spotting in the UK's biggest survey

The biggest bat survey ever carried out in Britain is underway.

And it is a team effort between experts and AI.

Researchers left devices on poles among the trees of 310 woodlands, recording 98 million bat calls over three years, which would have taken more than 30 years to study without AI.

BBC reporter Harriet Bradshaw went out in the dark to try to spot them.