- Invasive species are animals and plants which have been moved from their native habitats by humans to other parts of the world where they have a negative impact upon native species and indirectly economies.
- The domestic cat is described as an invasive species in most of the world but they can’t be described as an invasive species in the places where the wildcat became domesticated which extends in an arc from northern Egypt in the east to Iraq in the West.
- A comprehensive global report on invasive alien species has been signed off by 143 governments.
- The report was organised by the United Nations through the Intergovernmental Science Policy Platform on Biodiversity and Ecosystem Services.
- Prof Helen Roy, is an author of the report who is based at the UK Centre for Ecology & hydrology in Oxfordshire.
- The report found that there were 37,000 invasive species worldwide.
- The number is growing by 200 a year.
- The report says that invasive species cost $423 billion (£336 billion) a year mainly through their impact on other species and plants.
- The best British example is the introduction in the 19th century of the gray squirrel. The gray squirrel carries a virus which is deadly to red squirrels which is confined to islands and Scotland as a consequence.
- The report which is 200 pages long says that invasive species are responsible for 60% of extinctions (of native species in the countries to where the invasion species have been transported).
- With increased global trade and climate change the spread of invasive species is increasing.
- The researchers warned that there needs to be intervention in the number of invasive species which is set to rise by more than 33% by 2050 compared to 2005 levels.
- New Zealand has set a target of 2050 to eradicate all invasive species according to The Times report. This would mean that the domestic cat is going to be eradicated in New Zealand which is untrue. This must apply to feral cats which are greatly disliked by a large majority of New Zealanders because they prey on their precious native species.
- The UK has been successful in stopping the Asian hornet from establishing itself and eradicating muskrats.
- Prevention is better than reaction to the problem which requires good proactive management. Comment: there is little chance that this will happen as governments are generally reactive and slow moving.
- Raccoons, according to Roy, have been “very problematic” in other parts of Europe.
- Almost 200 countries (which I presume is the entire planet) have signed up to a deal in Canada to safeguard biodiversity by measuring the progress of invasive species against a target to halve the rate of these species establishing themselves by 2030.
- The North American signal crayfish grows up to 15 cm in length. They carry diseases that have caused British varieties to decline.
- A fungal disease called ‘sudden oak death’ is spreading through British wetlands and accelerating problems for native trees.
- Floating pennywort is an invasive plant which chokes rivers in the UK.
- The American mink are members of the weasel family and they prey on Britain’s water voles.
- The killer shrimp is an invasive freshwater shrimp and it is “altering the communication structures of other invertebrates” in the UK according to Roy.
- The bane of homeowners, Japanese knotweed, damages buildings because of its deep roots and it is very hard to remove.
- Plant life is damaged by the rhododendron which grow rapidly.
- The harlequin ladybird is an American invader linked to the decline of some of Britain’s native ladybirds.
- A Japanese “squirt” species called the carpet sea squirt attaches itself to marine structures creating a carpet that blocks out other species.
My thanks to The Times report of September 5, 2023.
