The Threat of Invasive Species Across the UK May be Greater than You Think

Non-Native and Invasive Non-Native Species (also known as NNS and INNS respectively) are very rarely talked about, but the damage that they are doing locally and globally is pretty incredible.

The main difference between an invasive non-native species and a non-native species is the impact that they have. Non-native species have either a neutral or positive impact, whilst invasive species have a negative impact on the ecosystem they are introduced to.

Currently we have over 3,000 INNS in the UK, which makes up around 15% of all non-native species in total. It is estimated that INNS cost the UK £1.7 billion per year. The estimated total annual costs of INNS to England is £1,288,262,000, Scotland £250,144,000 and Wales £132,244,000. INNS are also seen to be the second biggest threat to global biodiversity after habitat loss, and with the rise in globalisation making transportation easier, and global warming forcing species to move, this could continue to grow.

To give more of an idea as to where this cost comes from, here are some figures taken from the GB non-native species secretariat (NNSS) website:

– £13.9m of damage per year estimated to be caused by deer vehicle collisions (many of which were non-native species)

– £11m estimated to be the cost that would be required to eradicate rhododendron from a national park in Wales

– £100,000 spent by one water works on modifications to cope with Zebra Mussels
 – £10m estimated cost to British timber industry of squirrel damage to beech, sycamore and oak woodland

– £1m delay was caused to a road development scheme while waiting to treat Japanese Knotweed

– A Scottish Government report estimated the potential Net Economic Value loss to Scotland of the introduction of the salmon parasite Gyrodactylus salaris at £633 million with severe consequences for rural communities.

INNS can cause a number of issues for native wildlife; in fact, INNS have been involved in the extinction of 68 out of the 135 bird species lost in the wild globally over the last 500 years. The main issues that they present are:

– Introducing new diseases

– Competition for resources

– Hybridisation, which occurs when the non-native species breeds with the native species which can cause the unique genetic diversity of one species, usually the native species, to become extinct

– Predation; most native species cannot adapt quick enough when a new predator is added to the ecosystem

The Ruddy Duck: By Derek Bakken from Minneapolis, MN – Ruddy Duck, CC BY 2.0,

This is just a quick overview of some of the issues being faced in the UK when it comes to Non-Native species. When you take a look at what is happening across the globe, it is difficult not to be surprised by the scale of the problem. The total loss to the world economy as a result of invasive non-native species has been estimated at 5% of its annual production. Globally, INNS have contributed to 40% of the animal extinctions that have occurred in the last 400 years, and over 80% of the world’s islands have been invaded by rodents. Marine life is one of the most affected, with 84% of the world’s 232 marine ecoregions reporting the presence of invasive non-native species.

Unfortunately there just doesn’t seem to be much research on NNS and INNS, especially in the UK. One of the main challenges is that it is difficult to tell which non-native species will turn into an invasive species until it is too late. Whilst being able to prevent INNS being introduced in the first place may be an impossible task, being able to act quickly to prevent them from becoming established could be key to controlling and managing this issue. Removing INNS from an ecosystem has proven successful in the past, allowing that ecosystem to return to its natural state.

There are many notable invasive species. The grey squirrel, which originated in North America and entered Britain in the 1870’s has wiped out the majority of the red squirrel population. The red squirrel can only be seen in a small number of places, including the Isle of Wight (having grown up there I only saw one, and that was on a visit to my family at the age of 31, so they aren’t exactly common). Ruddy ducks, again originating in North America have been breeding with white-headed ducks to such an extent that there is concern that the white-headed duck will be completely wiped out by hybridisation. The ring-necked parakeet, a common site in London parks and with reported sightings through the South-East of England, is one of the biggest INNS in the bird population. Then there is the Asian Hornet; a huge threat to bees which are already suffering devastating losses in numbers, the public are urged to report any sightings of the Asian Hornet to the Centre for Ecology and Hydrology here.

The UK Government has “The Great Britain Invasive Non-native Species Strategy”, originally released in 2008 and updated in 2015. So far the strategy has mostly focused on the removal of fauna such as Japanese Knotweed and Water Primrose, a much less controversial focus than that of the removal of wildlife. The Convention on Biological Diversity (CBD) recommends prevention as being the best way forward, and this strategy recognises that whilst that has been a key aim, it is one that they have struggled with. However, it will continue to consider this a high priority moving forward. With 10-12 new NNS becoming established in the UK per year, it also recognises the need to be knowledgeable and predict in advance potential NNS arriving in Britain, and to determine if any of these could become invasive. Whilst it is a difficult threat to manage, it is one which needs to be taken seriously as the damage it is causing – both financially and ecologically – is already high. The strategy is due for review every five years, so it hopefully won’t be long before we receive an update as to how efforts have been progressing.

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Jessica Howard

Jessica Howard

31 years old, currently living and working in London, UK.

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