Muntjac Deer originally come from China but were introduced to the UK
A project to record and count the invasive species of Great Britain has been launched.
Four of these alien species can be found in Oxfordshire and can have a destructive effect on local wildlife.
Members of the public can take part by taking photos and submitting them to the GB Non-Native Species Secretariat (NNSS) website.
It follows the successful Harlequin Ladybird survey which helped scientists identify the insects' impact in the UK.
BBC Oxford spoke to Project Co-ordinator Peter Brown and Dr Helen Roy of the Centre for Ecology and Hydrology in Oxfordshire to get the lowdown on the species native to Oxfordshire that we should be looking out for.
"We needed species that would be able to be identified by the public," Peter Brown explained.
"Anything obscure wouldn't be a candidate. It's about the level of impact the species may have."
Helen Roy outlined the problem: "Because humans are moving around the globe at an increasing rate and frequency, the appearance of these species along with them is inevitable.
"But we can be the eyes and ears of biodiversity and watch out and see what is arriving."
"These species have all come into Britain because of people," Peter Brown concurred.
"We need to be more careful in terms of plants used in gardens, animals escaping from wildlife parks and things being deliberately introduced.
"A lot more care is needed.
"Things have improved a lot and we now know more about some of these species that perhaps 100 years ago there was no thought given to."
The majority of the new arrivals to Britain do not have a negative impact.
"Many of them are really welcome additions," said Helen Roy.
"99% of all the new species that arrive in Britain aren't going to cause any problems but it's the rest that we want people to be really watching out for and reporting on to allow us to make decisions about them."
Muntjac Deer (Muntiacus reevesi)
"The Muntjac Deer was an escape from Woburn Safari Park over 100 years ago.
"The major problem that it causes is that it grazes quite prolifically on the low plant species, causing damage to the flowering plants that we like to see in our woodlands.
"They also cause collisions on roads and that's quite a concern." HR
"It's suited to the climate here and has done extremely well and expanded its range very rapidly.
"The main impact is on the ground flora and increasingly in gardens. It's causing people problems when eating flowers and fresh shoots.
"The sheer numbers of them have got so big. We don't have any wolves or the big predators of the past that would have controlled their numbers." PB
Zebra mussels are native to Russia and came to Britain via ships
Zebra Mussel (Dreissena polymorpha)
"The Zebra Mussel is one of the classic non-native species. It first arrived in ballast water on ships in the 19th century.
"There are signs in recent years that it's expanded its range, becoming abundant and starting to spread.
"This one has impacts on wildlife as well as economic impacts.
"Thousands and thousands of the mussels all together lock gates and even affect fisheries by clogging everything up and getting onto ships." PB
"It gets in rivers and various waterways.
"They affect the water quality and the other creatures that live in and around that water body.
"They do have a nuisance factor.
"In the waterways which have pipes and ducts going out of them the Zebra Mussel can form such dense colonies that they actually block the pipes." HR
Tree of Heaven threaten native species as they sprout on disturbed ground
Tree of Heaven (Ailanthus altissima)
"The Tree of Heaven tends to do better in warmer climates but there are signs that it's becoming invasive in Britain.
"It's more of an urban species and is often planted in parks.
"It sends out suckers that can damage pavements and walls. In the right conditions it can spread very quickly." PB
"It has the capacity to get to large heights and can outcompete the native plant species around it.
"By affecting these plant species you get knock on effects to other things beyond that.
"You can find them in any open areas where their seeds can take and start to begin to grow.
"They're very good at doing what they do and when they arrive in a suitable place they really take off." HR
American Skunk-cabbage (Lysichiton americanus)
American Skunk-cabbage is spreading from gardens into the country
"People have enjoyed planting the American Skunk Cabbage in their gardens but it seems to be spreading out into the wider countryside.
"It reaches really high numbers - you see great swathes of it where it occurs." HR
"It is the one we know least about.
"It's a big thing with great big yellow spathes or flower-like structures up to about 45 or 50 centimetres long with great big cabbage-like leaves.
"It can crowd out and shade out other plants in wet woodland which is quite a rare and vulnerable habitat now.
"It has potential to do damage to other plants but we don't know how that's going to take off." PB