Christmas Island, an Australian territory in the Indian Ocean south of Java, is the scene of one of the world’s most extraordinary migrations. With the start of the wet season, tens of millions of bright red land crabs leave the forest and march to the coast to breed, covering roads, rocks and beaches in a moving red carpet.
At a glance
| Best time | The first rains of the wet season, usually October to December |
| Getting there | Flights from Perth (about 4 hours) |
| Time needed | 5 to 7 days |
| Big draws | Red crab migration, robber crabs, seabirds, snorkelling |
| Good for | Wildlife enthusiasts, photographers |
The migration
- Christmas Island red crabs live in the rainforest, where they help recycle leaf litter. See our Christmas Island red crab profile.
- When the wet season begins, usually in October or November, adult crabs begin migrating to the coast. The timing is triggered by rain.
- Males arrive first, dig burrows and mate. Females stay in the burrows for about two weeks while their eggs develop.
- The females release their eggs into the sea at the turn of the high tide before dawn during the last quarter of the moon. The exact dates are predicted each year by Parks Australia.
- About a month later, if the larvae survive, tiny baby crabs emerge from the sea and march inland in huge numbers.
Protecting the crabs
Roads are closed during peak migration, and special crab bridges and underpasses help crabs cross. In the past, invasive yellow crazy ants killed millions of crabs; control programmes, including the release of a biological control wasp, have helped.
Other wildlife
- Robber crabs (coconut crabs): the world’s largest land-living arthropod. See our coconut crab profile.
- Seabirds: Abbott’s booby (which nests only on Christmas Island), Christmas Island frigatebird, red-footed boobies, golden bosuns (a colour form of the white-tailed tropicbird).
- Marine life: excellent snorkelling and diving, with spinner dolphins and, from about November to April, whale sharks.
When to go
The migration usually starts between October and December, depending on the rains. Check Parks Australia’s predictions for spawning dates before booking. The migration is less predictable than a calendar event, so allow a week.
Getting there
Flights from Perth take about four hours, sometimes via the Cocos (Keeling) Islands. Accommodation on the island is limited, so book early for migration season.
Frequently asked questions
When is the red crab migration? Usually starting in October to December with the first wet season rains. The spawning dates are linked to the moon and tides.
How many red crabs are there? Estimates put the population at tens of millions, often cited as around 40 to 50 million adults.
Can I drive during the migration? Some roads close; others remain open with care. Follow instructions from Parks Australia.
Is Christmas Island only for crabs? No. It has excellent birdwatching, rainforest walks, snorkelling and diving year-round.
Related guides
- Monarch butterfly reserves in Mexico
- Kasanka bat migration
- Swimming with whale sharks at Ningaloo Reef
- Animal profiles: Christmas Island red crab, Coconut crab, Magnificent frigatebird
Cover photo: DIAC images, CC BY 2.0, via Wikimedia Commons