The public is being asked to report sightings of any coypus, sometimes mistaken for otters, after one was spotted in or near the River Lee near the Lee Fields in Cork City a week ago.
It is one of a number seen since last year beyond the Curraheen River, that feeds into the River Lee from the south.
It is believed that two or three of the rodents were released into the Curraheen River two years ago, near the Cork greyhound track in Bishopstown.
Since then, the National Parks and Wildlife Service (NWPS) has trapped around 10 coypus on or near the Curraheen.
But with reports from other locations becoming more frequent, it is now seeking the public’s help to monitor their spread, as it is on a list of major environmental concerns across the EU.
“Their burrowing can undermine river banks and possibly coastal defences, and they can do a lot of damage to crops, especially root crops that they feed on,” said NWPS south-west region conservation ranger, Danny O’Keeffe.
With millions of pounds having to be spent in a decades-long eradication programme in Britain, keeping track of their spread is essential to restrict the potential longer-term costs associated with the invasive species.
The South American natives look like a very large rat, weighing between five and nine kilos, and measuring as long as a metre from the head to the tip of the long tail.
The coypu has dark fur with lighter ends, a white muzzle, long cylindrical tail and distinctive orange or yellow teeth.
While the NWPS has caught several coypus on the Curraheen, they have also got reports of sightings seen in a stream near the old rail viaduct on the Cork-Bandon road, south of the Curraheen and in the Monkstown area of Cork’s lower harbour.
An unconfirmed report also suggests a dead coypu was seen in the northside suburb of Blackpool, which has a number of rivers and streams.
The service now needs to compile as much information as possible to adopt control plans elsewhere.
Mr O’Keeffe said people might see them swimming in rivers, or scurrying around river banks like an otter.
“The more records we have, we can bait the areas, set traps, and in areas they are using constantly, we can get in a shooter,” Mr O’Keeffe said.
“If someone sees a coypu, it’s fine if they want to get a photo. The main thing to let us know is the location, date and time,” he said.
Any sightings of coypu can be notified by calling or texting Danny O’Keeffe at 087 2472264 or email firstname.lastname@example.org