Giant rat-like creatures called coypu are spreading in the wilds here, having been first introduced to Ireland as pets.
Native to South America, the coypu is one of the biggest rodents in the world, weighing 5kg-7kg and measuring a metre long.
Also known as the river rat, it is often mistaken for an otter - but can be identified by its long, round tail and orange or yellow teeth.
The National Parks and Wildlife Service (NPWS) says it has trapped 10 coypu in or around the Curraheen area in Cork since the creatures were first seen in the River Curraheen two years ago. The NPWS is now urging the public to inform it of any sightings in an attempt to monitor the spread.
Colette O'Flynn, invasive species officer for the National Biodiversity Data Centre, said it was unusual to see a coypu in the wild.
"It is known mainly for being a pet species. It is likely that someone brought one or more here as a pet and they escaped into the wild," Ms O'Flynn said.
She said that the rodent could cause damage to the environment if it was not properly monitored or controlled.
"This is all about understanding what we're dealing with here by finding out how many coypu there are in the area now. We need to ascertain how spread out they are from where the first one was seen.
"The problem is coypus are herbivores.
"They eat plants, which means they will eat a lot of the riverside vegetation which other wildlife depend on," Ms O'Flynn said.