Extinction

A species is said to be extinct after the last known member of the species has died, and no more known members of that species are seen alive. The official IUCN definition is: there is no reasonable doubt that the last individual has died-after an exhaustive survey in known or suspected habitat at appropriate times (day-night, seasonal) throughout its historical range, and the survey was done over a time frame appropriate to the species' life cycle (IUCN Red List: Categories and Criteria) Seven species have become extinct since 2000; 39 in my lifetime, and 784 (plus 60 extinct in the wild) since 1500 A.D.

Most species typically become extinct within 10 million years of its first existence. However, since humans have existed, species extinction has accelerated at an unprecedented rate. Current extinction rates are 50-500 times higher than rates in the fossil record. Some experts predict that half of presently existing species will be extinct by 2100 (E.O. Wilson, The future of life, 2002). As of October, 2008, almost one-quarter of the world's mammals are in danger of extinction. The natural extinction rate had been about one every 100-200 years. Now it is one each year; this rate could be ten each year, and by 2099 ? to ½ of all species are predicted to be extinct. This rate of extinction has not been seen since the end of the dinosaurs, 65 million years ago. (Recently Extinct Animals)

Causes of Extinction by Humans

• We hunt them-over-exploitation (industrial fishing fleets, well-armed poachers)
• We destroy their homes (habitats) by chopping down forests, plowing grasslands, and by pollution.
• We introduce some species which become pests, and they then destroy native species; they become an invasive alien species.
• Climate Change-global warming: causes species to move up the mountain or to the North/South Poles (to cooler climes). Bleaching of coral reefs: raising the acidic content of seawater kills plankton and other crustaceans at the bottom of the food chain.

Non-manmade Causes of Extinction

• Lack of genetic diversity
• Limited geographic range
• Abrupt change in environment-asteroid slamming into Earth
• A bacteria or virus causes

Our Earth is the only one we have. If we destroy it, we destroy ourselves.

Extinction in the Wild

Extinct in the Wild means that there is no member of the specie living free in their natural habitat. Some members are living in a protected habitat such as a Zoo. They could also be living in a facility for captive breeding with the goal to re-introduce them into their natural home environment. One example of success with this method is the Peregrine Falcon (The Peregrine Fund). California Condors have been re-introduced into the wild, but it is too early to tell if this specie will be saved, but it looks good so far.