Previous experiments conducted in Kenya have isolated patches of land from megafauna such as zebras, giraffes and elephants, and observed how an ecosystem reacts to the removal of its largest species. Rather quickly, these areas become overwhelmed with rodents. Grass and shrubs increase and the rate of soil compaction decreases. Seeds and shelter become more easily available, and the risk of predation drops. Consequently, the number of rodents doubles -- and so does the abundance of the disease-carrying ectoparasites that they harbor. "Where human density is high, you get high rates of defaunation, high incidence of rodents, and thus high levels of pathogens, which increases the risks of disease transmission," said Dirzo, who is also a senior fellow at the Stanford Woods Institute for the Environment. "Who would have thought that just defaunation would have all these dramatic consequences? But it can be a vicious circle."More via DailyKos.
Biologists (yet again) sound the alarm in this latest article via Stanford News Service, warning that 16 to 33 percent of vertebrates are now endangered. Larger animals such as elephants, rhinos and polar bears face the highest decline rates, which follows in the pattern of past extinction events. The loss of such creatures would mean devastating trickle-down effects on the human population and other species.