AT’s intrepid eco-explorer Inger Van Dyke heads to idyllic Christmas Island only to discover there’s a war going on . . .  

“A rocky outcrop 360km south of Jakarta is an unlikely place for natural warfare. OnChristmas Island, however, a full-scale battle is being waged between the island’s native crabs and some feisty invaders. Yellow Crazy Ants, feral cats and rats are staging a united front in a war againstChristmas Island’s famous crabs.

Described by Sir David Attenborough as “the world’s greatest migration”, the Red Crabs of Christmas Island are endearing little critters. Casually combing the forest floor, they graze on leaf litter until wide expanses of newly cleaned earth are opened. Then once a year, in a cloud of supercharged hormones, they leave their forest and freshwater home to enter the sea. On the shorelines, at high tide on the last quarter moon in November precisely, female crabs perform a disco dance with claws raised and bottoms a-jiggle while they release millions of eggs into the ocean. It’s one of the most prolific breeding frenzies on the planet. Once in the water, the eggs hatch, and the young make their way back to land to contribute to the cycle.

Sharing this remote island paradise with Red Crabs are Blue Crabs and probably the largest intact population of Robber Crabs on earth. As a motor vehicle-bound tourist or resident on the island, it’s extremely bad karma to run any of them over. Driving over a Robber Crab carefully so they end up between your wheel span could land you with a 40cm hitchhiker hanging off your chassis sporting a nasty attitude. “They tend to rise up if they feel threatened,” warned my partner. He was right.

The 1000 or so Australian residents ofChristmas Islandhave grown accustomed to crabs. Holes in the impossibly scenic golf course are often used by Red Crabs as rest stops on their way to sea. Losing a ball off the course adds a dimension to the game that’s unique to the island: Robber Crabs lie in wait at the edge of the greens and will often mistake golf balls for coconuts, making them a formidable opponent if you try to wrestle with one to get your ball back.

During peak migration, more than 100 million Red Crabs scuttle through the forests and community to the coast. Leaving your door open is a welcome invitation to red-clawed guests, and school children step over low boards to enter classrooms so they don’t share their lessons with red invaders.

The relationship between people and crabs is a harmonious one. Perhaps it’s the laid back, sultry pace of life or the sheer beauty of the island’s landscapes that fosters this friendliness. Limestone grottoes, sandy keyhole bays and blowholes dot the precipitous cliffs lining the coast. Thick jungles fed by freshwater springs crown the hillsides. Floating on thermals high above, large, canary yellow Golden Bosunbirds with long streamer-like tail feathers share the air with frigatebirds and boobies. Coral reefs teem with life in tepid ocean waters around the island’s fringe. In an idyllic world such as this, sinister problems are lurking.

Accidentally introduced Yellow Crazy Ants, so called for their fast and frantic movements, invade the subterranean homes of Red Crabs, spraying the occupants with lethal formic acid and forming multi-queened colonies. Parks staff have deployed several methods of control but progress has been slow and arduous due to the island’s rugged terrain. Attacking the island’s remaining endemic wildlife is a scourge of feral rats and cats that have evolved their palettes from crabs to devour reptiles such as Christmas Island Blue-tailed Skinks and ground-nesting feathered friends like the Gold and Silver Bosunbirds.

At the Golden Bosun Tavern, we chat with a small group of naturalists and Parks staff about the conservation of Christmas over a few beers and an extravagantly colouredIndian Oceansunset. At a neighbouring table, a group of scuba divers celebrated their dive with one of the island’s Whale Sharks while another group of visiting birders exchanged stories of watching Great Frigatebirds drinking and endemic Abbotts Boobies nesting. At the bar, enthusiastic tourists regale each other with tall tales of encounters with Robber Crabs and swap tips on how best to avoid making road pizza out of their newly found red friends.

Visit soon before the wildlife conversations at the Golden Bosun change forever.

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