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Unusually dry weather in Australia has caused an historic two-month delay in the annual Christmas Island red crab migration.

The spectacular event usually takes place around November and sees some 50 million red crabs travel from their home in the island forests to the ocean.

Experts say climate change has played a part in the delay to this crucial breeding process.

Brendan Tiernan, who is the Parks Australia threatened species field programme coordinator said the last "six to nine months of 2023 was exceptionally dry.

"So dry, that in October and November when the crabs would usually migrate, we had no rainfall. And that dry period continued into January this year".

With a population of tens of millions, the crabs are unique to the island in the Indian Ocean and are protected by Australian law.

The migration prompts road closures. Authorities also create special migration bridges for them to climb on so they can avoid the roads.

February 2024 is the first time these red crabs are known to have migrated so late.

They usually travel during the first rainy days of the year.

Did you know the Moon also plays an important factor in when the crabs decide to migrate?

Red crabs all leave their burrows at the same time when the Moon is in its third-quarter phase.

Once they have mated, the female crabs stay in little burrows on the beach for a few weeks while their eggs grow.

When the Moon reaches its final quarter and the tide is high, the female crabs will head into the water just before dawn to lay their eggs - which hatch straight away into tiny crab larvae.

Then the adult crabs will head back home into the forests, with the babies following when they have developed enough.