7. Why are introduced, invasive species such a big problem on islands?

Of the nearly 250 recorded animal extinctions since 1500, 80% have been on islands. When causes could be determined, non-native, invasive species were responsible for 54% of these island extinctions.

Island species are especially vulnerable to extinction because of their small populations and limited habitat. Many island species have also evolved in isolated environments with limited competition and an absence of native predators. These island species are adapted to ecosystems that are comparatively safer than most continental ecosystems, making them vulnerable to introduced, invasive species. Non-native species often quickly alter and damage the ecosystems to which they are introduced, both directly and indirectly, and cause native species to decline or even become extinct.

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