The country’s rich biodiversity owes a great deal to its geological history. Around 65 million years ago, North and South America were joined by a land bridge not unlike what exists today. Around 50 million years ago however, the continents split apart and remained separate from one another for millions of years.
During this time, unique evolutionary landscapes were created on both continents. In South America, there was an astonishing diversification of many species. The land soon gave rise to many bird families (toucans and hummingbirds included), unique neotropical rodents (agoutis and capybaras) and groups like iguanas, poison dart frogs and basilisks. In North America, which collided repeatedly with Eurasia, animal species that had no relatives in South America (horses, deer, raccoons, squirrels and mice) flourished.
The momentous event that would change natural history for both continents occurred around three million years ago when the land bridge of Panama arose. Species from both continents mingled as northern animals went south and southern animals went north. Many found their homes in the lush forests and wetlands along the isthmus, where the great variety of plant species created ideal conditions for nourishing wildlife.
Today, the interchange of species between North and South America is limited to winged migrations, though this annual event can be breathtaking to behold.