The invasive Brown Tree snake (Bioga irregularis) - A native of Australia, Indonesia, Papua New Guinea, and the Solomon Islands,
the brown tree snake is thought to have hitchhiked to Guam on military aircraft in the late 1940s or early 1950s.The brown tree
snake is a serious threat to the biological diversity of tropical islands and is most infamous for its near complete extermination of Guam’s native forest birds.
There are a variety of causes of extinction and loss of biodiversity. Drivers may include (but are not limited to) pollution, climate change, overharvesting, large environmental events or disasters, introduction of non-native species, habitat destruction and fragmentation, and genetic issues or demographic phenomena. Habitat loss and fragmentation has been considered the primary culprit of species extinctions to date, but some recent work has now identified invasive species as the front runner in the extinction race.
When a non-native species is introduced to a new location there is the potential for it to become abundant and dominate an ecosystem. Provided there was a large enough invading population upon arrival, the species has the biological characteristics to survive, reproduce and establish and the environmental conditions of the receiving ecosystem are appropriate, invasives have the potential to cause environmental damage, interrupt ecosystem processes, cause losses to local biodiversity or eventually even local extirpation.
Some claim that native species are no less likely than invasive species to cause environmental damage, including biodiversity loss. A study by University College London (UCL) researchers recently published in Frontiers in Ecology and the Environment compared how frequently invasive and native species have been implicated as drivers of known extinctions (since 1500) in a comprehensive global database, the 2017 International Union for Conservation of Nature (IUCN) Red List of Threatened Species.
“Some people have suggested that aliens are no more likely than native species to cause species to disappear in the current global extinction crisis, but our analysis shows that aliens are much more of a problem in this regard,” said lead researcher Professor Tim Blackburn of UCL Biosciences.
The numbers really speak for themselves.
Since the year 1500, invasive species have been solely responsible for 126 extinctions (13% of the total number studied).
Of the 953 documented global extinctions, 300 were the result in-part to invasive species and of that 300, close to half, 42%, had invasive species as the sole cause of the extinction.
Out of 782 listed animal species and 153 plant species, 33.4% and 25.5% listed invasives as an extinction driver respectively. Contrary to invasive species, the impacts of native species were associated with only 2.7% of animal extinctions and 4.6% of plant extinctions. Further to that, the number of animal extinctions caused in-part by invasive species is more than 12 times greater than those of native species.
So, what does this mean looking forward? To try and curb these high extinction rates resulting from invasive species increased biosecurity is required to prevent future invasions. This may include better predictive tools, stiffer border controls, cost-effective and efficient treatment/management options, improved communication and education on invasive species and their impacts, establishing international regulations and better ways to hold people/organizations/companies/governments/countries accountable for their actions. As trade cross continents, oceans and seas increases and travel times decreases the risks of transporting viable invasive to new localities will grow as well. There is a great deal of fundamental research required and hopefully studies like this one can help put invasive species receive the recognition they deserve.
To download this UCL study please see the following link:
For information on the IUCN assessment process please visit their website:
Find out more about the world's worst invasive species by visiting the IUCN's Invasive Species Special Group (ISSG) Global Invasive Species Database (GISD).
For information regarding invasive species in British Columbia, Canada please visit the Invasive Species Council of BC’s website. www.bcinvasives.ca
