SummaryReliable population size estimates are imperative for effective conservation and management of globally threatened birds like the ‘Critically Endangered’ Blue-throated Macaw Ara glaucogularis. Endemic to one of South America’s largest grassland floodplains, the Llanos de Moxos in northern Bolivia, the species’ global population size is uncertain. The region’s inaccessibility renders the application of traditional methods for obtaining bird population estimates impracticable or cost prohibitive. We developed a simultaneous, multilocality, double-sampling approach combined with quantitative habitat availability analyses to obtain the first rigorous population size estimate for the Blue-throated Macaw. We established 11 survey areas across its three subpopulations that were visited twice by one team in each subpopulation over a 23-day period in the 2015 dry season and obtained additional count data from two roost sites. We classified suitable habitat (palm forest islands) using Landsat 8 images and CLASlite forest monitoring software. We extrapolated the number of macaws detected (conservative estimate of the total number of macaws [CETN], highest single count [HSC]) per 100 ha of suitable habitat in each survey area to the entire area of suitable habitat in all subpopulations combined, corrected for the species’ range occupancy of 34.3%. The total number of Blue-throated Macaws detected by survey (CETN) and roost site counts was 137. Across all survey areas, the number of macaws per 100 ha of suitable habitat was 4.7 for the first and 4.4 for the second period for CETN and 3.2 and 3.4, respectively, for HSC data. Corresponding global population estimates were 426–455 (CETN) and 312–329 (HSC) individuals. Other recent research and anecdotal data support these estimates. Although it would be premature to propose downlisting the species to ‘Endangered’, our findings indicate that it has a larger population and slightly larger range than previously thought, and that the positive effects of conservation actions are now becoming apparent.

中文翻译：

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第一个系统抽样方法来估计极度濒危的蓝喉金刚鹦鹉 Ara glaucogularis 的全球种群规模

摘要可靠的种群规模估计对于有效保护和管理全球受威胁的鸟类（如“极度濒危”蓝喉金刚鹦鹉）至关重要Ara 青光眼。该物种是南美洲最大的草原洪泛区之一，玻利维亚北部的 Llanos de Moxos 特有的，其全球种群规模尚不确定。该地区的交通不便使得应用传统方法来获得鸟类数量估计不切实际或成本过高。我们开发了一种同步、多地点、双采样方法，并结合定量栖息地可用性分析，以获得蓝喉金刚鹦鹉的第一个严格的种群规模估计。我们在其三个亚种群中建立了 11 个调查区域，每个亚种群中的一个团队在 2015 年旱季的 23 天内访问了两次，并从两个栖息地获得了额外的计数数据。我们使用 Landsat 8 图像和 CLASlite 森林监测软件对合适的栖息地（棕榈林岛屿）进行了分类。我们将每个调查区域中每 100 公顷合适栖息地中检测到的金刚鹦鹉数量（保守估计的金刚鹦鹉总数 [CETN]，最高单计数 [HSC]）外推到所有亚种群中合适栖息地的整个区域的总和，更正该物种的范围占有率为 34.3%。调查发现的蓝喉金刚鹦鹉总数 (CETN) 和栖息地数量为 137 HSC 数据分别为 3.2 和 3.4。相应的全球人口估计为 426-455 (CETN) 和 312-329 (HSC) 个体。其他最近的研究和轶事数据支持这些估计。虽然提议将该物种降级为“濒危”还为时过早，