The central-peripheral hypothesis states that the demographic performance of a species decreases from the centre to the edge of its range. Peripheral populations are often smaller and tend to occur under different and suboptimal conditions from those of core populations. Peripheral populations can also coexist during part of their annual cycle with populations from the core of the species’ range. Studies on peripheral populations are thus valuable for broadly understanding ecological and evolutionary processes. The Two-banded Plover (TWBP, Charadrius falklandicus, Charadriidae) is an endemic South American shorebird that breeds in Argentine and Chilean Patagonia and migrates northward during the Austral winter. There are breeding records, however, from Lagoa do Peixe National Park in southern Brazil. In this study, we (i) mapped TWBP nests, (ii) characterised their reproductive biology and nesting habitats, (iii) colour-marked birds and evaluated their seasonal occurrence patterns and (iv) estimated the size of the Brazilian population by combining supervised habitat classification analyses and generalised additive models. We estimated that the Brazilian population has 55 (95% CI: 44.1–66.6) breeding pairs and found that the length of their breeding season was roughly 5 months, spanning the Austral spring and summer. The population’s nesting habitat differed, and their apparent reproductive success was lower than that of core populations. Unlike more southerly populations, the results of our mark-resighting efforts demonstrate that the Brazilian population is sedentary. Taken together, these results indicate that the Brazilian TWBP population seems geographically isolated from the species’ southernmost core populations, resulting in a heteropatric distribution. Furthermore, differences in nesting habitat and year-round residency indicate that this peripheral population is ecologically distinct. The marked behavioural and ecological differences combined with the small population at the northern edge of the TWBP distribution support the central-peripheral hypothesis in a Neotropical system.

中文翻译：

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双带鸻（Charadrius falklandicus）在其分布北部边缘的繁殖栖息地、物候和规模

中心-外围假设指出，一个物种的人口统计学表现从其分布范围的中心到边缘递减。外围种群通常较小，并且往往发生在与核心种群不同且次优的条件下。外围种群也可以在其年度周期的一部分与来自物种范围核心的种群共存。因此，对外围种群的研究对于广泛了解生态和进化过程很有价值。双带鸻 (TWBP, Charadrius falklandicus, Charadriidae) 是南美特有的滨鸟，在阿根廷和智利的巴塔哥尼亚繁殖，并在澳大利亚冬季向北迁徙。然而，巴西南部的 Lagoa do Peixe 国家公园有繁殖记录。在这项研究中，我们 (i) 绘制了 TWBP 巢穴图，(ii) 描述了它们的生殖生物学和筑巢栖息地，(iii) 用颜色标记的鸟类并评估了它们的季节性发生模式，以及 (iv) 通过结合受监督的栖息地分类分析和广义加法模型。我们估计巴西人口有 55 对（95% CI：44.1–66.6）繁殖对，发现它们的繁殖季节长度大约为 5 个月，跨越南方春季和夏季。种群的筑巢栖息地不同，并且它们的明显繁殖成功率低于核心种群。与更偏南的人口不同，我们重新定位的结果表明巴西人口是久坐不动的。综上所述，这些结果表明巴西 TWBP 种群在地理上似乎与该物种最南端的核心种群隔离，导致异域分布。此外，筑巢栖息地和全年居住地的差异表明这种外围种群在生态上是不同的。显着的行为和生态差异与 TWBP 分布北边缘的小种群相结合，支持新热带系统中的中心-外围假设。我们重新审视标记的结果表明，巴西人口是久坐不动的。综上所述，这些结果表明巴西 TWBP 种群在地理上似乎与该物种最南端的核心种群隔离，导致异域分布。此外，筑巢栖息地和全年居住地的差异表明这种外围种群在生态上是不同的。显着的行为和生态差异与 TWBP 分布北边缘的小种群相结合，支持新热带系统中的中心-外围假设。我们重新审视标记的结果表明，巴西人口是久坐不动的。综上所述，这些结果表明巴西 TWBP 种群在地理上似乎与该物种最南端的核心种群隔离，导致异域分布。此外，筑巢栖息地和全年居住地的差异表明这种外围种群在生态上是不同的。显着的行为和生态差异与 TWBP 分布北边缘的小种群相结合，支持新热带系统中的中心-外围假设。导致异域分布。此外，筑巢栖息地和全年居住地的差异表明这种外围种群在生态上是不同的。显着的行为和生态差异与 TWBP 分布北边缘的小种群相结合，支持新热带系统中的中心-外围假设。导致异域分布。此外，筑巢栖息地和全年居住地的差异表明这种外围种群在生态上是不同的。显着的行为和生态差异与 TWBP 分布北边缘的小种群相结合，支持新热带系统中的中心-外围假设。