Photograph of raccoon dog by Marc Baldwin

They may not be a fixture in our local parks or countryside but experts at the Mammal Society are concerned that raccoon dogs have the potential to become a problematic invasive species in Britain.

A member of the fox family, raccoon dogs (pictured above) are wild animals which are native to Japan, Siberia and China. In previous years, the animals have been brought into Britain as exotic pets; however, it is now illegal to buy or sell one in this country.

As well as having a reputation as the escapologists of the mammal world, raccoon dogs are very adaptable, a troublesome combination which means that if a raccoon dog is released or escapes from captivity, it is likely to thrive, as they have done in some other European countries where they are considered a pest.

In the Horizon Scanning study, funded by Defra and with the GB Non-Native Species Secretariat (GB NNSS) (published December 2019) invasive non-native species were reviewed. The aim of the review was to identify those species which were not yet present in the wild in Britain but could arrive and have the potential to have most negative impact. Of 243 species reviewed, two mammals were included as high risk in the top 20 list, they were the raccoon and the raccoon dog.

Helen Roy, principal scientist at the UK Centre for Ecology and Hydrology, and one of the authors of the study, explains why the two mammals have the potential to cause so many problems. “We assessed many, many potentially invasive non-native species for inclusion on the horizon scanning list. Raccoons and raccoon dogs, were ranked within the top 15 most worrying invasive non-native species on the horizon because of their impacts on biodiversity, both feed on a variety of small animals but they also transmit a number of diseases to humans. Therefore, they are both a concern to nature and people. The top 15 also included plants, such as the two-leaf water milfoil, and invertebrates, such as the Asian hornet. Making such predictions about invasive non-native species is important to inform biosecurity and particularly approaches to prevent the arrival of these damaging species in the first place.”

Raccoon dogs are classed as an invasive non-native species (INNS), which means that not only have they been moved from their place of origin and brought into Britain by humans but that they can also have a negative impact on the environment, the economy or human health. It is estimated that around 10-15% of non-native species belong in the INNS category but the proportion for mammals is much higher and the number of new arrivals is increasing every year.

Dr Stephanie Wray, new Chair of the Mammal Society, says “While there has been only one reported sighting of a raccoon dog this year, in Lincolnshire, there are a small number of sightings around Britain each year. Luckily, these have been sightings of single animals so far, but wild animal populations can grow remarkably quickly, and the raccoon dog is a very adaptable animal which can breed quickly and survive on a wide range of food.  Once breeding in the wild, they can spread very quickly.  We need to be mindful of their potential impact on our native species and report any such sightings as soon as possible. You only have to look at the decimation of water vole numbers, which were already struggling with habitat loss, before predation by invasive American mink to see the damage which can be done over a relatively short period of time.”

This week (24-30 May) is national Invasive Species Week and the Mammal Society are calling on the public to record signs and sightings of any invasive mammals they spot, including unusual records like raccoon dogs and raccoons, but also more easily seen mammals such as the four invasive deer; fallow, sika, muntjac and Chinese water deer; rabbit; grey squirrels or rats or house mice to name a few. You can record wild mammal sightings using the free Mammal Mapper app or by completing a quick and easy form on the Mammal Society website

Records received help the Society to build a better picture of wild mammal populations and distribution in Britain which in turn will help us to advise on appropriate conservation action. To reduce confusion about what is a non-native or invasive mammal, the Society has produced a position statement