Over the past 50 years, humans have thrown many ecosystems out of balance. We have pushed roughly 40 percent of plant species to the verge of extinction, and approximately two-thirds of wildlife has been lost. Many scientists and naturalists are shifting focus from protecting a particular species or place of beauty to rebuilding entire ecosystems that can sustain themselves with minimal human interference.
Rewilding attempts to restore ecosystem balance by trusting natural environments to recover by themselves with maybe a little initial push. Often, this nudge is reintroducing a keystone species to areas where it has become extinct. Keystone creatures are ones that have a structural role in a natural community disproportionate to their abundance; frequently, they are large, wide-ranging predators (mammals, raptors, large fish, etc.).
Yellowstone is the best-known rewilding project, where 14 wolves were reintroduced in 1995. The obliteration of wolves in Wyoming 100 years earlier led to big increases in elk herds and eventually to overgrazing of grasses, and even aspen and willows. Hindering the growth of riparian trees deprived birds and beavers of their natural habitat. Moreover, the water temperature rose from lack of shade, negatively affecting fish and other aquatic creatures. Within 20 years, the wolf population has normalized and rebalanced the park’s ecosystem to its biodiversity.