Hundreds of bats were counted during the study
Bat numbers have soared in the Ben Lomond area, according to a study by the National Trust for Scotland (NTS).
In Ardess Lodge, which houses the trust's offices, more than 90 bats were spotted, up from 21 last year.
More than 300 of the flying mammals were seen at Blairvockie Farm and about 500 were noted at an information block at Rowardennan car park.
The bats were mostly soprano pipistrelles, a species common throughout Scotland.
More bats were found in the Ben Lomond area, which is at the east side of Loch Lomond, than at any other NTS site.
Lindsay Mackinlay, nature conservation adviser at the trust, said: "These findings show both that this area of Ben Lomond has some of the biggest roosts and that the roosts appear to be in a very healthy state.
"As bats are given such high conservation priority by law, seeing them in such large numbers on trust ground is very encouraging."