Once said to be as numerous as ants, Bermuda Land Crabs in their thousands used to make for the water from their inland burrows. On the stretch between Spittle Pond and John Smith’s Bay, cars couldn’t help but crush the animals on their way to spawn. The crabs, then seen as pests, were in houses, roads, and golf courses. But today you’ll likely only find a leftover claw here or legs there, the remains from a heron’s dinner. Where have the crabs all gone?
The Bermuda Land Crab is a stocky, medium-sized crab that lives in burrows on the land, often quite a distance from the ocean. Deep red in colour with a dark purple back, they are terrestrial crustaceans that only return to the sea to spawn.
Unfortunately, the trek from the burrow to the sea is often treacherous due to coastal roads and passing cars. Before the island became motorized, the crabs had a much easier journey.
Another reason why the crab population has been drastically reduced has to do with their main predator, the Yellow-crowned heron. In pre-colonial Bermuda, the land crab’s population exploded out of control because the early settlers had decimated populations of their predatory heron. Upon this more recent realization, environmentalists eventually worked to introduce the Yellow-crowded Night Heron, from which the pre-colonial heron in Bermuda was clearly derived. The heron has done its job nicely.
Today, land crab populations seem less abundant than they really are because the crabs have learned not to venture out of their burrows unless there is a good reason. They can feed from the burrows on rootlets, and not risk predation by herons by spending too much time on the surface.
In their journeys by moonlight to reproduce, they release thousands and thousands of eggs, which hatch almost immediately after they hit the water. Then, the tiny crablets, smaller than a fingernail, climb out of the water and back up the cliffs to mature. The production of so many offspring is a tactic by animals with high mortality rates – all of their young are never expected to survive, only a tiny percentage.
When the heron does manage to catch a crab dinner, it bashes its victim against rocks on the shoreline, scattering body parts as it does. This is probably all you will see of the Bermuda Land Crab.