The results can be disastrous. This increase in the rate of habitat destruction is directly linked to the rise in human population. People also affect plant and animal habitats when they take wood, oil, and other products from the land. Sometimes an introduced species causes no obvious harm, but in other cases the introduced species causes serious problems. The worst of these problems is when introduced species begin to prey on native species and cause them harm.
Overexploitation is another reason species become endangered.
One example of this is the case of the great whales, many of which were reduced to extremely low populations sizes in the mid-20th century because of unrestricted whaling. In 1982 a number of countries agrees to put a ban on commercial whaling. As a result, some whale species that used to be endangered have made great comebacks. Many other species, however, are still at risk. Some other animal species experience high rates of exploitation because of the trade in animal parts .