Australia-  Millions of red crabs head to the sea to lay their eggs in their annual migration, turning Christmas Island a fiery red.

More than 50 million red crabs make the journey from the jungle to the coast on Christmas Island in northwest Western Australia. Locals and visitors often share many images documenting one of the largest animal migrations on the planet when crabs turned the island red. Red crabs crawl across roads, bridges, rocks and along streams to reach the spawn point in time. They even appear in some strange locations like cliffs and city centers.

Conservation staff on the island spent several months preparing for the migration by building special bridges for crabs and temporary barricades. Dr. Tanya Detto, Christmas Island’s invasive species program coordinator, said the land had never been so populated with migratory crabs since 2005. He and his team spent a lot of time arranging bridges and fences. barrier to help red crabs move safely to Flying Fish Bay.

According to Detto, although experts on the island can predict the route the crabs will take, the route still changes slightly each year. A few crabs got stuck crawling over three-story buildings or falling off limestone cliffs, but most survived. The migration season usually begins when the first rain of the rainy season falls in October or November. The male crabs will leave the burrow and head to the beach, taking the female crab along the way.

The exact timing and speed of migration are determined by the lunar phase. This year, experts predict that the crabs will lay eggs on November 29 or 30. The crabs know exactly when to leave the cave to reach the beach in time to lay eggs most smoothly. Each female crab will lay 100,000 eggs in the Indian Ocean for 5-6 consecutive nights during the migration. A month later, the baby red crab returned to shore to make the journey back to the island’s rainforest. However, the majority of larvae will be eaten by fish, rays and whale sharks lurking in the surrounding waters.

Christmas Island manager Bianca Priest shares this natural event that takes place on the island every year. Christmas Island National Park has erected kilometers of makeshift barricades, directional signs and sealed off roads to protect millions of crabs.