Great Britain is in the top 10% of areas for harbouring alien species, according to a study.
Animals that have moved in from afar include the gray squirrel, rose-ringed parakeet and the noble false widow spider.
The UK also has more established alien plants than elsewhere in Europe, such as Himalayan balsam.
Scientists say islands and mainland coastal regions are global “hotspots” for alien species.
They are calling for more effective measures to stop further introductions of plants and animals into vulnerable ecosystems.
“We need to be much better at trying to prevent the introduction of species that can be harmful in the first place, ” said Dr Wayne Dawson of Durham University, UK. “Prevention is better than remedy with invasive species.”
Alien species are plants or animals that are non-native( or alien) to an ecosystem and whose introduction might very well cause harm.
International researchers examined data on eight groups of plants and animals across 186 island and 423 mainland regions.
Great Britain is 29th out of 540 regions( countries, nations or island blocks) in terms of established alien species( of which a subset are invasive) The top three global “hotspots” for alien species are the Hawaiian Islands, the North Island of New Zealand and Indonesia’s Lesser Sunda Islands Hawaii has high numbers of alien species in all eight groups studied, including fish such as guppies and mammals such as feral pigs New Zealand is not far behind Hawaii, with around half of plant life being made up of non-native species. Many native birds have suffered from predation by mammals such as rats, cats and possums Among coastal mainland regions, Florida in the US is the top hotspot, with invasive ants and reptiles such as the Burmese python Image caption