Every year, after the first spring rains, a huge number of land crabs cover the territories close to Playa Girón on their way to Bahía de Cochinos (Bay of Pigs). Red, black and yellow crabs migrate from the nearby forests to the bay to spawn in the sea at the end of their mating season. They cause chaos on the roads, cover house walls and the beach road which curves around the bay. The smell of crushed crab is everywhere, and their shells damage car tires. Despite being smashed by cars and pedestrians, they still complete their long journey to ensure survival of their species.
Cubans don't take advantage of this mass migration because they believe this crab species is toxic. Gecarcinus ruricola and lateralis are not endemic to Cuba, and according to Cuban officials they survival is not threatened by the migration through heavily urbanized areas. After releasing eggs at the Bay of Pigs, crabs return to their forest burrows and in a few weeks are joined by baby crabs who repeat their parents' journey from the sea.
The mass crab migration usually starts in late March, peaking in April. You might still spot some crabs in May and June, but not as much.