Threatened, Endangered and Extinct
From top left: Hawaii Oo, Golden Toad, Passenger Pigeon
From bottom left: Tecopa Pupfish, Caribbean Monk Seal
Scientists estimate that there are millions of different species species of animals on Earth. Many species have stable populationspopulations and are doing fine. Their numbers fluctuate from year to year but overall there are enough new animals being born to replace the animals that die.
For some animals, this is not true. Animals whose numbers decrease consistently are in danger of becoming extinct. Scientists call these animals endangeredendangered. Animals that are likely to soon become endangered are called threatenedthreatened.
Sometimes animals become extinct or endangered for natural reasons, without humans having anything to do with it. And sometimes, humans cause changes that lead to a population or species' decline.