### Snake Island (Ilha da Queimada Grande)
Brazil — Trapped by rising seas, ordinary snakes evolved into tree-dwelling, bird-hunting assassins with flesh-melting venom.
About 11,000 years ago, melting Ice Age glaciers caused eustatic sea levels to rise across the globe. This rushing water swallowed the land bridge connecting a rocky hill to mainland Brazil, trapping a population of ordinary pit vipers on a newly formed, isolated island.
This geographical lockdown triggered a dramatic case of "allopatric speciation." With no ground-dwelling mammals left to eat, the snakes faced starvation. Through rapid natural selection, they moved into the canopy to ambush migratory songbirds. But if a bitten bird flew away before dying, the snake still starved. To survive, the snakes had to upgrade their biological weapons.
The result is the golden lancehead viper, a hyper-specialized reptile armed with fast-acting hemotoxic venom three to five times deadlier than its mainland cousins. The venom is so potent it practically melts avian tissue, killing birds almost instantly. While local legends claim the island crawls with five snakes per square meter, biologists estimate the true population is between 2,000 and 4,000. That is still dense enough that the Brazilian Navy has made visiting strictly illegal.