- Predation and Extinction: Invasive predators such as feral cats and foxes have been responsible for the decline and extinction of many small native mammals and birds. Feral cats, for instance, are a major factor in the extinction of 30 Australian native mammal species since European settlement[3][5].
- Competition for Resources: Invasive species often outcompete native animals for food and habitat. For example, European rabbits consume large amounts of vegetation, depriving native herbivores of food sources[2]. Similarly, invasive fish like carp dominate aquatic ecosystems, outcompeting native fish species[5].
- Habitat Degradation: Invasive herbivores such as rabbits, goats, and deer degrade habitats by overgrazing and trampling vegetation. This leads to soil erosion and a decline in vegetation diversity, which adversely affects the entire ecosystem[5].
- Disease Transmission: Some invasive species carry diseases that can spread to native wildlife, livestock, and even humans. For example, feral cats can transmit diseases to other animals[2].
- Ecosystem Alteration: Invasive plants can alter habitats by forming dense infestations that displace native flora. This can lead to reduced biodiversity and changes in ecosystem structure[3]. For instance, the yellow crazy ant has significantly altered the ecosystem on Christmas Island by reducing native crab populations[3].
- Economic Impact: The presence of invasive species also has economic repercussions, costing Australia billions in management and control efforts, as well as losses in agriculture and tourism[3].
Overall, invasive species pose one of the most significant threats to Australia’s biodiversity by disrupting ecological balance, leading to the decline or extinction of native species.
Sources
[1] birds and mammals threatened by invasive species https://www.abs.gov.au/ausstats/[email protected]/94713ad445ff1425ca25682000192af2/0542a2bdf511788bca256bdc00122411!OpenDocument
[2] How Do Invasive Species In Australia Affect The Ecosystem? https://www.eastcoastmulching.com.au/invasive-species-in-australia/
[3] Australia’s silent invaders – Curious – Australian Academy of Science https://www.science.org.au/curious/earth-environment/invasive-species
[4] Threatened Species https://fnpw.org.au/news/latest-news/australian-threatened-species/
[5] Invasive Species – NSW State of the Environment https://www.soe.epa.nsw.gov.au/all-themes/biodiversity/invasive-species
[6] A strategy for dealing with invasive species in Australia https://invasives.org.au/our-work/feral-animals/strategy-invasive-species-australia/
[7] An inventory of threats https://www.nespthreatenedspecies.edu.au/media/sphgvm15/4-4-5-threats-to-threatened-species-findings-factsheet.pdf
[8] 10 of the Most Endangered Species in Australia in 2024 | Earth.Org https://earth.org/endangered-species-in-australia/
