Operation Land crab

Thursday 5th June 2014

A hardworking and, in my opinion, very cute animal spotted whilst I’ve been on Ascension Island is the Land crab (Johngarthia lagostoma), which spends much of its time inland in the island’s mountainous areas.

Here the climate is cooler and more humid than at the coast, where it is baking hot, dry and barren. However the crabs still need the sea to breed and every year they make an incredible journey from the mountains to the coast to spawn – this can be a rather hairy descent of several kilometres and over 800 metres.

Ascension Island’s only large native land animal, the Land crab is only found on four other South Atlantic islands, so it is pretty unusual.

Ascension Island is a stronghold for this species and so its protection is high on the list of the many conservation priorities here.

The crabs feed mainly on leaves, fruit and flowers, but their diet made them subject to persecution in the 1800s.

The British Navy garrisoned on Ascension quickly found that the crops they had planted were a tasty treat for the Land crab and they took divisive action. Between 1879 and 1887 soldiers killed a staggering 335, 535 crabs, motivated by a ‘reward’ of 1s 6d (would have been 7.5 p in today’s money) for every hundred pairs of Land crab claws turned in. This soon had a disastrous impact and by 1887 the population had crashed and soldiers had to go far and wide to even find a crab.

Whilst this practice no longer takes place, predators such as rats, mice and rabbits have found the crabs to be a tasty snack, putting further pressure on this fragile population.

Luckily the crab has clawed its way back and with help from ‘Operation Land crab’ it is hoped the population will recover. They may not be here in the same numbers as before but the populations are clearly on the up and with a better awareness of their importance they should be able to thrive.

Find out why Alice is visiting the UK Overseas Territories in our Bugs on the Brink project.