The Real Biodiversity Crisis

The numbers are grim: Some 2,000 species of Pacific Island birds (about 15 percent of the world total) have gone extinct since human colonization. Roughly 20 of the 297 known mus sel and clam species and 40 of about 950 fishes have perished in North America in the past cen tury. On average, one extinction happens some where on earth every 20 minutes. Ecologists esti mate that half of all living bird and mammal species will be gone within 200 or 300 years. Al though crude and occasionally controversial, such statistics illustrate the extent of the current