Thanks to global warming and habitat destruction, narratives about ‘invasive species’ have started to change
As human activity continues to heat the planet and destroy habitat for wildlife, plants and animals respond based on their genetic makeup and ability to adapt to altered environments. Some are losing ground, landing on ever-increasing lists of endangered species, or disappearing altogether. Others are making money, losing their lives by our side, or even profiting from the habitat modification we have brought about – raccoons, for example.
Science writer Fred Pearce notes that âmost of the losers are rare, endangered and endemic species, while most of the winners are common, generalist and invasive species – rats, mosquitoes, water hyacinths, etc. .
âAssisted evolutionâ initiatives aim to help wildlife species at risk adapt more quickly to their changing environments than generally slow evolutionary processes would normally allow. In Australia, a program aims to help the great bilby, an endangered marsupial, learn to avoid predation by intruders in their ecoregion – the feral cats and foxes introduced by British colonizers.
Cats have successfully adapted to their new surroundings and are not going anywhere. A team of researchers modified the standard conservation measure for construction fences to keep cats out, bringing them to fenced bilby shelters instead. This helps bilbies learn avoidance, a skill they need to survive in the wild.
Invasive species have long been recognized as key threats to native plants and animals. WWF’s Living Planet Canada Report 2020 identifies them as a major cause of the decline in wildlife here. But as plant and animal species around the world have started to shift their range in response to global warming and habitat destruction, narratives about invasive species have also started to change.
In the past, environmentalists viewed them negatively. Various eradication initiatives have been launched depending on the government’s landscape management capacity, the threat invasive species pose to species at risk or economic enterprises, proliferation levels and ease of eradication. (Think zebra mussels and purple loosestrife.)
There is now a good chance that species that enter new areas will leave habitats that are warming and degrading and benefiting from human stewardship. How should we respond? Should we differentiate between these âinvadingâ ecosystems as climatic or habitat exiles and those that human travelers have transported to new places?
Some scientists argue for such a differentiation. University of Vienna conservation biologist Franz Essl and colleagues propose that species that move or expand their range in response to human-caused environmental changes be classified as “neo-native” species, rather than âinvasive speciesâ, and that management guidelines reflect this distinction.
To some extent, science supports a distinction, as species that move on their own are more likely to keep pace with their natural counterparts than a species that, for example, arrives in the hull of a ship. .
Some scientists have proposed that the most logical way to determine how to deal with an invasive species is to assess whether its presence has an overall positive or negative impact on the ecosystem. As Mark Davis, professor at Macalester College writes, “Whether it is because of the climate or because people move them, species must be assessed on their own effects and not on whether they are native or new or non-native. or non-natives displaced by humans. ”
The effects of species on ecosystems are not unique, however, and consensus on ecological impacts does not always exist. This can lead to ideological differences in which some conservationists advance species eradication while others advocate for stewardship. As author Sonia Shah writes, âIn California, wildlife officials attempted to exterminate the Cordillera de Spartina, introduced west from the salt marshes of the Atlantic coasts and the Gulf of Mexico, despite providing feeding and nesting sites for endangered California valve rails. . ”
Ultimately, human pride drove many plants and animals to extinction. It is also the pride of trying to “manage” the species that have moved to new areas on the basis of our somewhat subjective analyzes to know if they do more harm or good.
It is clear that science alone cannot dictate a way forward. We need to incorporate other inputs, such as foresight, precaution, and indigenous knowledge when overseeing programs to limit or support wildlife populations on land and in water. If we are not careful enough to think through these complex issues, wildlife management will be driven solely by the economic value humans place on some plant and animal species over others.
The species most in need of better management is ours.
Written with the contribution of Rachel Plotkin, Boreal Project Manager of the David Suzuki Foundation. Learn more about davidsuzuki.org.