Investigations are under way in Donegal after 32 swans were found dead.
The dead swans were recovered from New Lake in Dunfanaghy over the weekend by conservation rangers.
It is understood some of the birds had been dead for some time.
An ill swan recovered from the lake was brought to a vet, but had to be put down.
Water samples have been taken from the lake and the dead swans have been sent to a Department of Agriculture facility in Sligo for further testing to determine the cause of death.
Poisoning, water pollution and a form of avian flu have not been ruled out.
New Lake is a nesting site for dozens of swans, ducks and other wildfowl, drawing bird watchers and tourists alike.
The public is advised to contact the National Parks and Wildlife Service if they come across ill or dead swans.