Troubled giants: The updated conservation status of the coconut crab (Birgus latro)

The coconut crab, Birgus latro (Linnaeus, 1767), the largest land arthropod in the world, is widely distributed on islands and atolls across the Indian and Pacific Oceans, but there is strong evidence that populations are declining in the face of anthropogenic threats. Here we review the data on population trends, habitat availability, distribution, and threats worldwide used by the IUCN Red List of Threatened Species to reassess the global conservation status of B. latro. The results indicate that crab populations are suffering declines in many parts of their range associated with urbanisation and coastal habitat fragmentation driven by increasing human populations and overexploitation. Immediate threats to B. latro include habitat loss, overharvesting, introduced predators, and road kills, while future threats potentially include sea level rises and ocean acidification. These widespread threats, coupled with the lack of protective conservation measures in most areas, together justify the elevated global extinction risk assessment change from Data Deficient to Vulnerable A2cd+4cd (IUCN version 3.1).