Members of Caerphilly Bird Rescue and around half a dozen supporters went to Caerphilly Castle on the evening of Monday, May 20, after a tip-off that a second cull was to take place.
However, Cadw’s South Wales Regional Manager Jackie Arrowsmith told Caerphilly Observer that said no such cull had been planned.
Caerphilly Bird Rescue had been told that contractors were due to attend the castle to remove ducks and geese.
In a post on its Facebook page Caerphilly Bird Rescue said: “A huge thank you to everyone who turned up at the castle…there is definitely something going on.”
The group has also called into question the legality of the culling as the general licence issued says alternative solutions must be sought.
These may include decoy models to act as a deterrent to the birds at the castle.
The type of general licence used by Cadw contractors to cull the birds is a general one issued by Natural Resources Wales under the Wildlife and Countryside Act.
In England, this type of licence is now no longer used after a legal challenge from campaign group Wild Justice, which was founded by TV presenter and conservationist Chris Packham.
A Natural Resources Wales spokesperson said it was considering its position in light of the change in England.