BIRDS ON THE BRINK

Found on all seven continents, birds are a vital gauge

of ecosystem health. Yet many species have had it

rough since at least 1500, when recordkeeping

began. During the rise of global trade in the colonial

era, birds in the biodiverse tropics, for example, were

hard hit by habitat loss and the introduction of invasive

species—threats that persist oday. Nearly 200

species are gone forever, according to BirdLife

International, the official authority for birds on the

International Union for Conservation of Nature (IUCN)

Red List of Threatened Species. Even more species

are critically endangered, many clinging to grim odds:

Fewer than 50 adults survive in the wild.