Conservationists believe a colony of lesser horse shoe bats in the Wye Valley has reached record numbers.
A total of 890 bats has been recorded living in the stone barn
Gloucestershire Bat Group recorder David Priddis, from Woolaston, has registered 599 flying adults and 291 babies in a small stone barn.
"The barn's only about the size of two goat sheds and the bats roost from less than two inches off the ground, right to the top of the rafters," he said.
He believes it is the largest colony of lesser horseshoe bats in England.
"The scale of the colony can be put into context when you consider that mainland European bat experts would consider a colony numbering 80 to be large," said Mr Priddis, who has been monitoring the roost since 1989
"The Lower Wye Valley probably has the greatest population of lesser horseshoes per square mile in Europe and it's one of the greatest strongholds in this country."