It’s hard to believe that extinction is happening right before our eyes. There are five primary causes: habitat fragmentation, pollution, introduction of invasive species, overexploitation and climate change. Here is a list of ten species that have been declared extinct so far this century. These are masterpieces of nature that we can no longer enjoy. We are running the Ecolympics (registration begins on March 21) to raise awareness of exactly this problem.
The same information is presented, with a stirring soundtrack and more photos, in the video below, produced by the MotherNatureChannel:
Both of these need to be updated to include the Eastern Cougar, declared extinct this year, though it's last confirmed sighting was in Maine in 1938.
You can also find a timeline of extinctions on Wikipedia.