The Threat of Invasive Species to Native Wildlife

Human health and economies are also at risk from invasive species.The impact of invasive species on our natural ecosystems and economy costs billions of dollars each year. Many of our commercial, agricultural and recreational activities depend on healthy native ecosystems.

A species is considered “invasive” when it is introduced to a new environment and causes significant harm to that ecosystem. It can be any kind of living organism – a non-native plant, an amphibian (like the cane toad), an insect, animals, fungus, bacteria, or even an organism’s seeds or eggs that is not native to an ecosystem and causes harm.

Invasive species can outcompete native species for resources, such as food and water. They can also prey on native species, or introduce diseases that native species are not immune to. This can lead to the decline and extinction of native species. 

Invasive species can also alter the physical environment in ways that harm native wildlife. For example, they can change the structure of forests, or introduce new pollutants into water bodies.

Invasive species are primarily spread by human activities. Often, unintentionally, people and the goods we use travel around the world very quickly, carrying uninvited species with them. Ships can carry aquatic organisms in their ballast water, while smaller boats may carry them on their propellers. Insects can get into wood, shipping palettes and crates that are shipped around the world. 

In addition, higher average temperatures and changes in rain and snow patterns caused by climate change will enable some invasive plant species such as garlic mustard, kudzu and purple loosestrife to move into new areas. Insect pest infestations will be more severe as pests such as mountain pine beetle are able to take advantage of drought weakened plants.

A stark example of how invasive species spread and the resulting devastation can be seen with the water hyacinth (Eichhornia crassipes) in Kenya. Initially introduced as an ornamental plant, this rapidly reproducing aquatic menace demonstrates the ease with which non-native species can establish themselves and proliferate. Its spread across Lake Victoria, chocking vast swathes of the water, and its encroachment into irrigation canals and rivers highlights how human activities, such as the introduction of non-native species for aesthetic purposes, can inadvertently trigger ecological disasters. This case vividly illustrates the mechanisms of invasive species spread, from initial introduction to rapid proliferation, and the subsequent disruption of ecosystems and livelihoods. 

A silent war is reshaping our planet’s ecosystems, fought with the insidious spread of invasive species. These biological invaders are pushing native wildlife to extinction, from coral reefs to African savannahs.

The introduction of the Argentine ant, for instance, has disrupted native ant populations, crucial food sources for various reptiles and birds. 

In areas like the Tsavo National Park, this disruption can lead to a decline in native insectivores, as their primary food source is outcompeted.

Furthermore, invasive plants like Prosopis juliflora, known locally as ‘Mathenge’, outcompete native grasses and shrubs, reducing grazing areas for herbivores like zebras and gazelles. This alteration in vegetation cover not only impacts herbivore populations but also affects the predators that rely on them, creating a cascading effect throughout the ecosystem. 

Preventing invasive species introductions is paramount. Once established, these invaders wreak havoc on ecosystems, driving native wildlife to extinction and costing billions in control efforts. Through strict biosecurity measures, public awareness, and careful import regulations, prevention is far more effective and cost-efficient than eradication. Every introduction carries risk; a seemingly harmless plant or pet can trigger ecological disaster. Prioritizing prevention is our fundamental responsibility to protect the planet’s natural heritage.  

If you see invasive species, you should report it to the appropriate authorities. You can also help them to control invasive species by removing them from your property and volunteering to help with eradication efforts. We can all do our part to help prevent the introduction of invasive species and to control those that are already here.