British Indian Ocean Territory Biodiversity Action Plan: Coconut Crab

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In the Chagos Archipelago, systematic surveys of coconut crabs have mostly concentrated on Diego Garcia (Fig. 5). On Diego Garcia, densities of coconut crabs appear to be among the highest recorded for this species anywhere in the world. In particular, Vogt and Guzman [12], using the DISTANCE transect methodology [13], found coconut crab densities on the east side of the island, in the Minni Minni conservation area, were on average approximately 300 crabs per hectare (and two of their transects in this area revealed density estimates of 467 and 489 crabs per hectare). These remarkably high densities are almost certainly linked to the abundance of coconut within the coconut plantations, which were planted centuries ago [14]. The high density of coconut crabs in the Minni Minni conservation area contrasted with lower densities of coconut crabs in areas of Diego Garcia that are not conservation areas: there approximately 150 crabs per hectare at the southern tip of Diego Garcia and approximately 50 crabs per hectare on the west side of Diego Garcia, the developed part of the island (Fig. 6). These density estimates are not without substantial error. However, a crude extrapolation of these estimates across the 2,719 hectares of Diego Garcia equates to a population size on Diego Garcia of several hundred thousand coconut crabs. No repeat surveys using the same methodology have been made on Diego Garcia since Vogt and Guzman’s study. Hence, the current population of coconut crabs on Diego Garcia may have changed. Continued yearly data is needed to track the trend of these population dynamics across time.


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StatwsHeb ei Gyhoeddi - 2020
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