Spring rains in southern Cuba mark the beginning of one of nature’s mass migrations: millions of yellow, black and red female land crabs, skitter-scattering across roads and beaches to deposit their fertilized eggs in the waters of the Bay of Pigs. Mating occurs in burrows in a nearby swamp, however, once the eggs are fertilized they must hatch in the sea. Having deposited their precious cargo, the mother crabs turn around and head for home, risking being snapped up or squashed by local Cuban crocodiles, black hawks, or locals of the human variety driving along the same road. Despite all these threats (and the threat of the newly-hatched baby crabs being eaten by fish lurking in the shallows) the crab population is still healthy. Indeed, the biggest threat to their survival is habitat destruction due to human development.

Watch the mass crab migration here.