How do invasive species devastate native ecosystems?

The answer

Invasive species are non-native organisms introduced to an environment where they lack natural predators, competitors, or diseases, allowing their populations to explode. The brown tree snake, accidentally introduced to Guam after World War II, drove 10 of 12 native forest bird species to extinction because the birds had no evolutionary experience with snake predators. Cane toads introduced to Australia in 1935 poisoned native predators that tried to eat them and have spread to cover over 1.2 million square kilometers. Zebra mussels in the Great Lakes filter so much plankton that they starve native species and cause billions of dollars in infrastructure damage annually. Invasive species are now considered the second greatest threat to global biodiversity after habitat destruction, contributing to approximately 60% of recorded animal extinctions worldwide.