The coconut crab Birgus latro, the largest terrestrial decapod, is under threat in most parts of its geographical range. Its life cycle involves two biomes (restricted terrestrial habitats near the coast, and salt water currents of the tropical Indian and Pacific Oceans). Its dependence on coastal habitat means it is highly vulnerable to the habitat destruction that typically accompanies human population expansion along coastlines. Additionally, it has a slow reproductive rate and can reach large adult body sizes that, together with its slow movement when on land, make it highly susceptible to overharvesting. We studied the distribution and population changes of coconut crabs at 15 island sites in coastal Tanzania on the western edge of the species' geographical range. Our aim was to provide the data required for reassessment of the extinction risk status of this species, which, despite indications of sharp declines in many places, is currently categorized on the IUCN Red List as Data Deficient. Pemba Island, Zanzibar, in Tanzania, is an important refuge for B. latro but subpopulations are fragmented and exploited by children and fishers. We discovered that larger subpopulations are found in the presence of crops and farther away from people, whereas the largest adult coconut crabs are found on more remote island reserves and where crabs are not exploited. Remoteness and protection still offer hope for this species but there are also opportunities for protection through local communities capitalizing on tourist revenue, a conservation solution that could be applied more generally across the species' range.

中文翻译：

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桑给巴尔椰子蟹 Birgus latro 的案例研究强调了全球威胁和保护解决方案

椰子蟹比格斯拉特罗最大的陆地十足目动物，在其地理范围的大部分地区都受到威胁。它的生命周期涉及两个生物群落（海岸附近受限的陆地栖息地，以及热带印度洋和太平洋的咸水流）。它对沿海栖息地的依赖意味着它极易受到沿海岸线人口扩张通常伴随的栖息地破坏的影响。此外，它的繁殖速度很慢，可以达到成年体型，再加上在陆地上的缓慢移动，使其极易受到过度捕捞的影响。我们研究了椰子蟹在该物种地理范围西部边缘的坦桑尼亚沿海 15 个岛屿的分布和种群变化。我们的目标是提供重新评估该物种灭绝风险状况所需的数据，尽管在许多地方都有急剧下降的迹象，但目前在 IUCN 红色名录中被归类为数据不足。坦桑尼亚桑给巴尔奔巴岛是重要的避难所B. 拉特罗但亚种群被分散并被儿童和渔民剥削。我们发现，在有农作物和离人类较远的地方发现了较大的亚种群，而在更偏远的岛屿保护区和未开发螃蟹的地方发现了最大的成年椰子蟹。偏远和保护仍然为该物种提供了希望，但也有机会通过当地社区利用旅游收入进行保护，这是一种可以更广泛地应用于整个物种范围的保护解决方案。