However, exotic species may also seriously disrupt delicate ecological balances and may produce a plethora of unintended yet harmful consequences. The worst of these unintended yet harmful consequences arise when introduced exotic species put native species in jeopardy by preying on them. This can alter the natural habitat and can cause a greater competition for food. Species have been biologically introduced to environments all over the world, and the most destructive effects have occurred on islands. Introduced insects, rats, pigs, cats, and other foreign species have actually caused the endangerment and extinction of hundreds of species during the past five centuries.
Exotic species are certainly a factor leading to endangerment.
Overexploitation A species that faces overexploitation is one that may become severely endangered or even extinct due to the rate in which the species is being used. Unrestricted whaling during the 20 th century is an example of overexploitation, and the whaling industry brought many species of whales to extremely low population sizes. Due to this moratorium, some whale species, such as the grey whale, have made remarkable comebacks, while others remain threatened or endangered. Due to the trade in animal parts, many species continue to suffer high rates of exploitation. Even today, there are demands for items such as rhino horns and tiger bones in several areas of Asia.