Two hedgehogs found dead in the Beaumaris area are thought to have eaten rat poison.
They were found on July 18, with the incident reported to the RSPCA a few days later.
RSPCA inspector Andrew Broadbent said: “We understand rat poison is being used locally and it appears these two hedgehogs may have consumed it.
“They were found very near to each other, on a Beaumaris path.
Mr Broadbent added: “Concerns are heightened as there are a number of hedgehog families thought to be living in the local area – so we’re reminding the public as to the potentially fatal, unintended consequences of legal poisons to other wild animals.”