• Habitat loss and degradation affects 86% of all threatened birds, 86% of the threatened mammals assessed and 88% of the threatened amphibians.
  • Introductions of Invasive Alien Species that establish and spread outside their normal distribution. Some of the most threatening invasive species include cats and rats, green crabs, zebra mussels, the African tulip tree and the brown tree snake. Introductions of alien species can happen deliberately or unintentionally, for example, by organisms “hitch-hiking” in containers, ships, cars or soil.
  • Over-exploitation of natural resources. Resource extraction, hunting, and fishing for food, pets, and medicine.
  • Pollution and diseases. For example, excessive fertilizer use leads to excessive levels of nutrients in soil and water.
  • Human-induced climate change. For example, climate change is altering migratory species patterns, and increasing coral bleaching." - http://www.iucn.org/what/tpas/biodiversity/about/biodiversity_crisis/