A bird-watching hide in a woodland beauty spot has restricted its opening times after it was targeted by strangers meeting for sex.
Twitchers at Highnam Woods, near Gloucester, found their hideaway was attracting so-called doggers.
The Royal Society for the Protection of Birds, which runs the 119-hectare site, now says it opens the hide only when staff are present.
It remains padlocked shut at all other times and police are investigating.
Barry Embling, from the local RSPB group, said: "Voluntary wardens do patrol and it is a case of trying to keep business as usual.
"It is a problem and landowners around the country are blighted by it."
Bird feeding stations have also been moved away from the hide to a more exposed area near the car park.
The RSPB said it was forced into taking the action after complaints from members of the public and concerns among their volunteers.
A message on the Gloucestershire local group's bird-watching website said: "A number of visitors had called us to say they had experienced an uncomfortable and/or intimidating situation in the hide during the daytime.
"Action had to be taken to safeguard our visitors from further incidents within the hide."
A Gloucestershire Police spokeswoman said: "We are aware of certain activities taking place and have discussed the issue with the RSPB, advising them to keep the building locked or closed.
"Patrolling officers pay attention to this area and if offences do come to their attention, those involved will be dealt with appropriately."