Invasive Species: What you need to know and what you can do!

Invasive Species: What you need to know and what you can do!

You may be aware of the dangers to buildings from Japanese Knotweed, or the impact Grey Squirrels are having on our native Reds, but did you know that the introduction of invasive non-native species is the second biggest threat to global biodiversity after habitat loss!

In Britain alone, there are more than 3,000 non-native species. Many are harmless, but occasionally a species will establish and flourish in a way which can pose a threat to our native biodiversity.

The cost of dealing with invasive non-natives in Britain is estimated to be several billion pounds annually and invasive non-native species are not just a threat to biodiversity, they can also damage economic interests such as agriculture, forestry and fisheries.

People have a long history of moving animals and plants around the globe and – either deliberately or inadvertently –  allowing them to establish in new areas.  On the surface it may appear that the introduction of a new species is harmless, only for problems to appear once the species has become established.  Some species have been introduced intentionally for use in agriculture, forestry etc, and others as the accidental result of human activity, eg in ships’ ballast water or the transporting of goods.

Free from native predators and competition, the new non-native arrivals often flourish and sometimes create severe problems for native wildlife:

  • Predation – introducing new predators into an area can have devastating effects on the native wildlife and ecosystems. Native species are often not able to adapt quickly enough to the predators.
  • Competition for resources – introduced species can out-compete native wildlife for resources like food, breeding sites, space etc. Japanese knotweed, an introduced plant to the UK, forms dense stands which can prevent native plants from growing. This can change the habitat structure of an area, making it unsuitable for the other organisms that live there.
  • Introducing new diseases – introducing new diseases can have serious consequences, as native species will not have developed immunity. Signal crayfish, an introduced species to the UK, is a carrier and host of the crayfish plague, which can kill our native crayfish.
  • Hybridisation – some species are capable of breeding with another related but distinct species, creating hybrids. Over time, the unique genetic diversity of one species can be lost and the species can become extinct.
  • Preventing invasive non-native species from being introduced in the first place, or, if that fails, acting quickly to prevent them becoming established, are key to tackling this issue. In places where invasive non-natives are already present and considered a threat, control or eradication of the population may be considered.

The GB Non-native Species Secretariat (NNSS) has responsibility for helping to coordinate the approach to invasive non-native species in Great Britain. If you find a non-native animal or plant on your land or in the wild, you must report it to the NNSS at:

Below is a list of the current GB alert species. By recording any sightings of these species as quickly as possibly you could be helping to prevent the establishment of a new invasive non-native species.





We can all help prevent the spread of non-native species by:

  • Keeping any boats, clothing, footwear and equipment used in water free of invasive non-native species – remember to Check Clean Dry after use.
  • Be Plant Wise and don’t let your garden, pond, or aquarium plants enter the wild.
  • Taking care of your pets, never release them or allow them to escape into the wild. It’s cruel and could harm other wildlife.
  • Looking out for Asian hornet and other alert species and record your sightings.