Highly mobile seed predators contribute to interisland seed dispersal within an oceanic archipelago

Long-distance dispersal (LDD) is an essential event for species colonization and expansion in oceanic island ecosystems. Endozoochory by birds is an important factor promoting the LDD of plant seeds, but its contribution to interisland seed dispersal is still unclear. Here, we show possible seed dispersal by a seed predator pigeon, the Japanese wood pigeon Columba janthina, among oceanic islands in the Izu archipelago, Japan. Although some previous studies showed that most seeds swallowed by this pigeon are crushed, intact seeds were found in 44.5% of pigeon feces, indicating the contribution of these birds to seed dispersal. Seasonal population fluctuations and movements by pigeons between neighbouring islands which are 4 km apart by pigeons can promote interisland seed dispersal. We found seeds from fruiting trees not located on the islands where the pigeon feces were collected, which could have been transported from another island. Although many tree species overlap their fruiting ph...长距离扩散（Long-distance dispersal, LDD）是海洋岛屿生态系统中物种定居与扩张的关键事件。鸟类体内传播（Endozoochory）是促进植物种子长距离扩散的重要途径，但其对岛屿间种子扩散的贡献仍未明确。本研究以日本伊豆群岛的海洋岛屿为研究对象，证实了一种兼具种子捕食性的鸽类——日本林鸽（Columba janthina）具备跨岛屿种子扩散的潜在能力。尽管既往多项研究显示，该鸽类吞食的绝大多数种子会被碾碎，但44.5%的鸽粪样本中仍检出完整种子，这表明此类鸟类可参与种子扩散过程。该鸽类存在季节性种群波动，且可在相距4公里的邻近岛屿间移动，这一特性可有效推动岛屿间的种子扩散。研究团队在采集的鸽粪中，发现了采集地岛屿并未分布的结果实树种的种子，这类种子大概率是从其他岛屿携带而来。尽管诸多树种的结果物候存在重叠……