allows the crabs to increase their activity and stimulates their annual migration. The timing of their migration is also linked to the phases of the moon. During this migration, red crabs abandon their burrows and travel to the coast to mate and spawn. This normally requires at least a week, with the male crabs usually arriving before the females. Once on the shore, the male crabs excavate burrows, which they must defend from other males. Mating occurs in or near the burrows. Soon after mating the males return to the forest while the females remain in the burrow for another two weeks. During this period they lay their eggs and incubate them in their abdominal brood pouch to facilitate their development. At the end of the incubation period the females leave their burrows and release their eggs into the ocean, precisely at the turn of the high tide during the last quarter of the moon. The females then return to the forest while the crab larvae spend another 3–4 weeks at sea before returning to land as juvenile crabs. Life cycle The eggs released by the females immediately hatch upon contact with sea water and clouds of crab larvae will swirl near the shore until they are swept out to sea, where they remain for 3–4 weeks. During this time, the larvae go through several larval stages, eventually developing into shrimp-like animals called megalopae. The megalopae gather near the shore for 1–2 days before changing into young crabs only across. The young crabs then leave the water to make a 9-day journey to the centre of the island. For the first three years of their lives, the young crabs will remain hidden in rock outcrops, fallen tree branches and debris on the forest floor. Red crabs grow slowly, reaching sexual maturity at around 4–5 years, at which point they begin participating in the annual migration. During their early growth phases, red crabs will moult several times. Mature red crabs will moult once a year, usually in the safety of their burrow. Their lifespan is about 12 years. Diet Christmas Island red crabs are opportunistic omnivorous scavengers. They mostly eat fallen leaves, fruits, flowers and seedlings, but will also feed on dead animals (including cannibalising other red crabs), and human rubbish. The non-native giant African land snail is also another food choice for the crabs. Red crabs have virtually no competition