Understanding the patterns of displacement and site fidelity in blue land crabs (Cardisoma guanhumi Latreille, 1825) has important implications for their conservation and management. The central objective of this study was to analyze seasonal variations in site fidelity in C. guanhumi, a species that is intensively exploited in Brazil, in spite of being part of the Official National List of Critically Endangered Species. This species currently suffers multiple severe threats, such as overharvesting and habitat destruction. C. guanhumi were sampled monthly at four fixed sectors that were delimited at the upper fringe of a restricted-access mangrove at Itamaracá Island between April 2015 and March 2016. One thousand and seventy-eight individuals were captured, measured, sexed, weighed, and their color patterns registered. Of these, 291 individuals were tagged with PIT (Passive Integrated Transponder) tags. Ninety-seven individuals (size range 27.0–62.6 mm carapace width) were successfully recaptured, totaling 135 recapture events. The largest interval between marking and recapture was 331 days. Through the use of mark-recapture-based models, it was possible to estimate the local population as being 1312 (± 417) individuals (mean density 2.23 ± 0.71 ind. m−2). Considering the mean density of burrow openings and individuals, there were 3.4 burrow openings per individual. C. guanhumi showed a clear philopatric behavior. Seventy-seven percent of recaptured individuals were recaptured in their sector of origin, and the remainder in an adjacent sector. Site fidelity was higher in females. Males showed minimum site fidelity in October, which is most likely related to be the onset of the reproductive season. The present study opens new perspectives for the definition of reproductive seasons, based on seasonal changes in behavior, and thus to improve the conservation of exploited and severely threatened species.

中文翻译：

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使用PIT标签对红树林螃蟹（Cardisoma guanhumi Latreille，1825）在限制进入的红树林地区的站点保真度和种群结构进行了分析

了解蓝土地蟹的位移和保真度的模式（Cardisoma guanhumi Latreille，1825年）对其保护和管理具有重要意义。这项研究的主要目标是分析尽管在官方濒危物种国家清单中，但在巴西大量开发利用的C. guanhumi种群保真度的季节性变化。该物种目前遭受多重严重威胁，例如过度捕捞和栖息地破坏。从2015年4月至2016年3月，在Itamaracá岛的限制进入红树林的上边缘划定的四个固定扇区，每月对C. guanhumi进行采样。捕获，测量，定性，称重和称重178个个体它们的颜色模式已注册。这些，291个人被PIT（被动集成应答器）标签标记。成功地重新捕获了97个个体（大小范围为27.0–62.6 mm甲壳），共进行了135次重新捕获事件。标记和重新捕获之间的最大间隔为331天。通过使用基于标记夺回的模型，可以估计本地人口为1312（±417）个人（平均密度2.23±0.71 ind。m-2）。考虑到洞口和个人的平均密度，每个人有3.4个洞口。C. guanhumi表现出明显的哲学行为。被俘虏的人中有77％在其原籍地被俘获，其余人员则在邻近的地方。女性的部位保真度更高。十月份，男性表现出最低的现场忠诚度，这很可能与生殖季节的来临有关。本研究根据行为的季节性变化为生殖季节的定义开辟了新的视角，从而改善了对已开发和受严重威胁物种的保护。