Earth appears to be on the brink of its sixth great extinction event — the first in about 66 million years. One-fourth of all mammal species on the planet are currently considered “endangered,” and so are nearly twice as many species of amphibians.
Many would blame climate change and deforestation as major causes for worldwide fauna population drops, but there’s something else we do that may be even more catastrophic to wildlife — introducing non-native species to unsuspecting ecosystems.
The fifth major extinction, the one that killed the dinosaurs, was likely caused by an asteroid. The sixth one will be the result of human activity.
Australia hasn’t changed much since Europeans colonized in 1788. Its population density is incredibly low, and its wilderness has been minimally altered. Most of the continent is considered “the outback,” as settlers mainly stayed near the coast. However, compared to other areas of the globe, Australia’s mammalian wildlife are dying at incredible rates.
After the splitting of the supercontinent Pangea, earth’s species have had nearly 200 million years of mostly isolated adaptation and evolution. However, as humans began traveling between continents, we introduced non-native plants and animals to new habitats, to live alongside other organisms with whom they may not get along.
Over the past 200 years, more than ten percent of Australia’s 273 known native land mammal species have gone extinct. Comparatively, in North America, only one has disappeared since Europeans arrived.
The main culprits of the decline of Australia’s native mammals appear to be the continent’s feral cat and European red fox populations. These non-natives have thrived in the Australian outback, mostly by preying on the species that are now in danger of extinction.
Conservationists have attempted separating endemic species from non-native predators with some success. But other factors, such as irregular bushfire patterns and habitat fragmentation, have also posed a major threat to Australia’s diverse land mammal populations.