Controlling alien species

Alien or invasive species are those that have moved from one ecosystem to another where they were previously unknown

• People have been responsible for the movement of species about the globe by trading animals and plants or unwittingly carrying them on ships
• some species have been introduced as biological control agents to control pests

• the cane toad was introduced in Australia from Hawaii in 1935 to control an insect pest of sugar cane
  • in Australia, the cane toad has become a pest as it breeds rapidly and has spread across the eastern, northern and western parts of the country
  • the cane toad has few predators in Australia,  mainly because it produces a powerful toxin that kills most animals that eat it
  • the northern quoll is the species most at risk from invasion by cane toads as it tries to eat the toads
  • numbers of this endangered marsupial carnivore decrease steeply after cane toads invade its habitat
  • cane toads probably compete with some other amphibian species for food and are known to eat the chicks of a ground-nesting bird

• other alien species are escapes or animals introduced for sport
  • it is thought the rabbit, introduced to Australia in the 19th century, has been responsible for more loss of biodiversity than any…