The impacts of invasive species

News emerged this week linking the presence of invasive Burmese pythons with a severe decline in mammal populations in the Everglades national park in Florida. The scientific study, led by US scientists and published in Proceedings of the National Academy of Sciences, suggests the pythons have had a remarkable impact within just eleven years of their establishment as an invasive species in the 1.5 million acres park. In some areas, foxes, rabbits, raccoons and opossums have all but disappeared and the pythons have also been recorded as consuming deer and alligators. In their native habitats they predate animals the size of leopards.

Non-native species: A grey squirrel eating in a London park.



  The pythons in question are obviously large creatures with appetites to match and the scientists are working to understand how they influence community structure in complex ecosystems. Scientists in the UK are doing similar work, although our invasive non-native species generally influence the environment on a smaller scale. Well known examples that regularly appear in the UK national press include Grey squirrels, the Harlequin ladybird and Himalayan balsam.

Through one such project, Recording Invasive Species Counts , scientists hope to improve their understanding of the ecology and distribution of a number of species recognised as invasive, non-native species that are now established in Britain. It is co-ordinated by the National Biodiversity Network and the Biological Records Centre (part of CEH), in partnership with recording schemes for the animals and plants. (The project is funded by Defra).

The RISC project encourages members of the public to send in their sightings of a number of different species including muntjac deer, the chinese mitten crab and signal crayfish. While Britain has a great tradition of biological recording with well-established monitoring schemes for many different taxonomic groups, non-native species are under-recorded because in many cases they have not been the primary interest of researchers. We would encourage you to help change that by sending in your sightings! The evidence will prove valuable in the future, not just for ecologists but anyone with an interest in managing or enjoying the environment.

Further reading:

• Read a series of blog posts by Dr Helen Roy of CEH about invasive species in Britain
• Submit sightings to the Recording Invasive Species Counts project
• Severe mammal declines coincide with proliferation of invasive Burmese pythons in Everglades National Park (Open Access article)

Posted by Paulette.