Extinction is a part of existence and species have been known to become extinct before. But what is of concern today is the speeding up of the process due to human action and intervention. It is estimated that ninety nine per cent of threatened species are at risk due to human activities. With increase in population humans are clearing natural landscapes of forests and grasslands and in the process driving animals out of their habitat. Other human activities are polluting the rivers and oceans and damaging the plant and marine environment. Other harmful activities include hunting for sport or collection in museums.
Also due to increased globalization, plants and animals are often introduced in areas where they do not naturally belong. These species often find that their new environment is already degraded by humans or other factors. These prove catastrophic to native species.
Visit Animal Info - Information on Endangered Mammals  for exhaustive information on biology, ecology, habitat, and status of rare, threatened and endangered species of mammals
 Why it Concerns Us?
Human beings are dependent on bio-diversity. We depend on species, animals and plants, all across the whole planet, not only for our food, but for roofs over our heads, furniture and medicines. If we continue losing species we endanger our own welfare and that of the future generations.
Threatened species are further classified into the following three categories:
• Vulnerable species
Which are likely to become endangered unless the circumstances threatening their survival and reproduction improve.
• Endangered species
Those which are at a risk of becoming extinct because of their low numbers
• Critically endangered species
Those whose numbers continue to decrease significantly over the years.
 IUCN Red List of Threatened Species
The 2007 World Conservation Union or International Union for the Conservation of Nature and Natural Resources (IUCN) Red List of Threatened Species puts the number of known threatened species at 785. And those threatened with extinction number 16,306. Great Apes are critically endangered because of habitat loss, poaching and the deadly Ebola virus.The ranks of those facing extinction are joined by familiar species like the polar bear, hippopotamus and desert gazelles, along with ocean sharks, freshwater fish and Mediterranean flowers have joined the ranks of those facing extinction. See Reuter Video Report on 2007 IUCN Red List  Visit 2007 IUCN Red List of Threatened Species 
Some species improve
The IUCN Red List has reported that the survival odds of Mauritius (Echo) Parakeet, once dubbed ‘the rarest parrot on Earth’, is improving due to sustained conservation work by Mauritius Wildlife Foundation and the Durrell Wildlife Conservation Trust
Corals as Endangered Species
This year’s IUCN Red List has included coral as one of the threatened species for the first time and referred to climate change as the cause of threat. Floreana coral (Tubastraea floreana) and Wellington's solitary coral (Rhizopsammia wellingtoni) are listed as Critically Endangered, while Polycyathus isabela is listed as Vulnerable. This development indicates the extent of environmental threat to marine biodiversity and underscores the need for immediate corrective action. Corals are said to be affected by global warming which reduced nutrient availability around the Galapagos Islands in the Eastern Tropical Pacific Ocean, off South America.
 Classification of Threat in IUCN Red List
The IUCN Red Book has categorized the various stages of threats in the following classifications:
• EXTINCT (EX)
A taxon is Extinct when there is no reasonable doubt that the last individual has died. A taxon is presumed Extinct when exhaustive surveys in known and/or expected habitat, at appropriate times (diurnal, seasonal, annual), throughout its historic range have failed to record an individual.
• EXTINCT IN THE WILD (EW)
A taxon is Extinct in the Wild when it is known only to survive in cultivation, in captivity or as a naturalized population (or populations) well outside the past range. A taxon is presumed Extinct in the wild when exhaustive surveys in known and/or expected habitat, at appropriate times (diurnal, seasonal, annual), throughout its historic range have failed to record an individual. Surveys should be over a time frame appropriate to the taxon's life cycle and life form.
• CRITICALLY ENDANGERED (CR)
A taxon is Critically Endangered when the best available evidence indicates that it meets any of the criteria A to E for Critically Endangered (see Red List Categories and Criteria booklet – link given in Reference) and it is therefore considered to be facing an extremely high risk of extinction in the wild.
• ENDANGERED (EN)
A taxon is Endangered when the best available evidence indicates that it meets any of the criteria A to E for Endangered (see Red List Categories and Criteria booklet for details), and it is therefore considered to be facing a very high risk of extinction in the wild.
• VULNERABLE (VU)
A taxon is Vulnerable when the best available evidence indicates that it meets any of the criteria A to E for Vulnerable (see Red List Categories and Criteria booklet for details), and it is therefore considered to be facing a high risk of extinction in the wild.
• NEAR THREATENED (NT)
A taxon is Near Threatened when it has been evaluated against the criteria but does not qualify for Critically Endangered, Endangered or Vulnerable now, but is close to qualifying for, or is likely to qualify for, a threatened category in the near future.
• LEAST CONCERN (LC)
A taxon is Least Concern when it has been evaluated against the criteria and does not qualify for Critically Endangered, Endangered, Vulnerable or Near Threatened.
 Did you know?
Australia is home to between 600,000 and 700,000 species, many of which are found nowhere else in the world. About 84 per cent of plants, 83 per cent of mammals, and 45 per cent of birds are endemic - that is, they are only found in Australia
Red List Categories and Criteria booklet