An investigation is under way after several swans were reported missing from ponds in Gloucestershire.
A member of the public told police of a "noticeable drop" in the number of swans and ducks at ponds near the River Severn at Apperley, near Gloucester.
He said he had seen two men using large fishing nets in the area twice this month.
A police spokesman said: "Swans are a protected species and it is a criminal offence to interfere with them."
He asked anyone who sees anything suspicious to get in touch.