Blank Park Zoo says addax, once widespread across the Sahara Desert, have been driven to the brink of extinction by years of illegal poaching and habitat loss.

Humans have driven sharks and their cousins to the brink of extinction. The health of the entire ocean is at stake.

At the turn of the 20th century, the great zoological gardens of Paris, London and New York City would have been hardly recognizable by today’s standards. Animals large and small—those that had ...