Oceanic islands, due to their evolutionary history and isolation, play a dual role of having high endemicity and being vulnerable to extinctions, with most known extinctions occurring on islands. Plant–animal interactions are particularly important on islands, as island systems generally have low redundancy and are more vulnerable to disruption either via extinction or by invasive species. Here, we examined the fruit removal and seed predation of a keystone palm, Caryota mitis, on Narcondam, a remote oceanic island. The island endemic Narcondam Hornbill (Rhyticeros narcondami) was the sole seed disperser of the palm (90 hours; N = 15 trees), with mean (± SE) visitation rate being 0.23 (± 0.06) individuals per hour and fruit removal rates of 3.5 (± 1.5; range: 0–16) fruits per visit, indicating a lack of redundancy in seed dispersal of the palm on this island. Whereas the invasive rodent, Rattus cf. tiomanicus, was the sole predator of palm seeds (N = 15 individual fruiting palms, 416 trap nights). Overall, 17.1% of the seeds placed (N = 375 seeds) were removed. Seeds placed under and away from the canopy, and at different densities (2 plots with 10 seeds each; 1 plot with 5 seeds, respectively), showed similar removal rates. This indicates density-independent seed predation and the lack of safe regeneration sites for Caryota mitis, with potential deleterious effects on subsequent stages of the ‘seed dispersal cycle’. Here, from a data-deficient site, we provide baseline information on the plant–frugivore interaction of a keystone palm and the potential impacts of an invasive rodent.

中文翻译：

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印度纳尔康丹偏远海洋岛屿上的鱼尾棕榈 (Caryota mitis Lour.) 的食果和种子捕食

海洋岛屿由于其进化历史和孤立性，具有高流行性和易灭绝的双重作用，其中大多数已知的灭绝发生在岛屿上。植物与动物的相互作用在岛屿上尤其重要，因为岛屿系统通常冗余度较低，并且更容易受到灭绝或入侵物种的破坏。在这里，我们研究了梯形棕榈的果实去除和种子捕食，轻尾鱼尾草，在纳康丹，一个偏远的海洋岛屿。岛上特有的纳孔丹犀鸟（斑纹蓟马）是唯一的棕榈种子传播者（90小时；氮= 15 棵树），平均 (± SE) 访问率为每小时 0.23 (± 0.06) 个个体，每次访问的果实去除率为 3.5 (± 1.5；范围：0–16) 个果实，表明种子传播缺乏冗余这个岛上的棕榈树。而入侵啮齿动物，黄鼠参见蒂马尼库斯，是棕榈种子的唯一捕食者（氮= 15 棵结果棕榈树，416 个陷阱之夜）。总体而言，17.1% 的种子已投放（氮= 375 颗种子）被移除。将种子放置在树冠下方和远离树冠的位置，并以不同的密度（2 个地块，每个地块 10 颗种子；1 个地块，分别有 5 颗种子），显示出相似的去除率。这表明与密度无关的种子捕食和缺乏安全的再生场所轻尾鱼尾草，对“种子传播周期”的后续阶段具有潜在的有害影响。在这里，我们从一个数据不足的网站提供了有关基石棕榈的植物与食果动物相互作用以及入侵啮齿动物的潜在影响的基线信息。