In 1875, trillions of Rocky Mountain locusts gathered and began migrating across the western United States in search of food. The enormous swarm covered an area larger than California. Three decades later, these grasshoppers were extinct.
This fate is all too common for migratory species. Their journeys can make them especially vulnerable to hunting or fishing. They may move between countries, meaning protecting the species in one jurisdiction isn’t enough. And it’s hard for us to even know if they’re in trouble.
