Hunting for food and other reasons

Since the 1600s, commercial exploitation of animals for food and other products has caused many species to become extinct or endangered. For examplethe slaughter of great whales for oil and meatthe African rhinoceros, killed for its horn, the great auk became extinct in the 19th century because of over-hunting the Carolina parakeet perished as a species because of a combination of over-hunting and habitat destruction. Introduced diseases, parasites, and predators against which native flora and fauna have no defenses have also exterminated or greatly reduced some species. The accidental introduction of a blight, for example, eliminated the chestnut tree from North American hardwood forests. Predator and pest control also have adverse effects. Excessive control of prairie dogs, for example, has nearly eliminated one of their natural predators, the black-footed ferret. In Australia the introduction of rabbits and cats has caused the destruction of much of the wildlife. In Queensland the Great Barrier Reef is under serious threat by the Crown of Thorns starfish.