1. Waterbird‐mediated endozoochory is an essential mechanism for the dispersal of sessile organisms in freshwater ecosystems. However, in the neotropics there are no previous studies of how different waterbird species vary in the dispersal functions they perform, and how seasonality influences endozoochory. In this study, we identified plant diaspores dispersed in faeces of five South American waterfowl (Brazilian teal Amazonetta brasiliensis, yellow‐billed teal Anas flavirostris, ringed teal Callonetta leucophrys, coscoroba swan Coscoroba coscoroba, and white‐faced whistling‐duck Dendrocygna viduata).
2. We collected 165 faecal samples from five wetlands in southern Brazil surrounded by pasture and rice fields, then separated and measured intact seeds and other diaspores. Using generalised linear models, we tested how diaspore abundance and taxonomic richness differed among bird species and between cold (April–September) and warm (October–March) periods. We also analysed bird‐specific and seasonal variations in diaspore composition through principal coordinates analysis and permutational multivariate analysis of variance. We used indicator species analysis to determine which diaspore species discriminated between bird species and seasons. Finally, we measured diaspore length in order to analyse differences among waterfowl species in the size of diaspores dispersed.
3. We found 2,066 intact diaspores from 40 different plant taxa, including seeds of 37 angiosperms and diaspores of Lycophyta (Isoetes cf. maxima), Pteridophyta (Azolla filiculoides), and Charophyceae. There was at least one diaspore in 65% of all faecal samples. Diaspores of native amphibious and emergent plants were dominant. We found 1,835 diaspores (from 33 taxa) in the cold period but only 231 (23 taxa) in the warm period. Seeds of the grass Zizaniopsis bonariensis and of the sedge Rynchospora sp. were the most abundant taxa. A strong interaction between bird species and season was the most important predictor of variation in both taxonomic richness and abundance of diaspores. The taxonomic composition of diaspores differed among waterfowl species and season. Indicator species analysis identified 12 plant taxa associated with particular bird species and seasons. Coscoroba swan, the largest bodied species in our study dispersed a higher proportion (8.2%) of large (length >2 mm) seeds.
4. Despite considerable overlap, there are important differences in the plants dispersed by each species, and the smallest (ringed teal) and largest (coscoroba swan) birds are particularly different. All five waterfowl species are distributed over wide areas of South America and here we demonstrated that they are likely to be important plant vectors connecting wetland species at different geographical scales. Many of these plants have previously been assumed to lack mechanisms for long‐distance dispersal.

中文翻译：

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新热带水禽的种子传播取决于鸟类种类和季节

1. 水鸟介导的内吞作用是固着生物在淡水生态系统中扩散的重要机制。但是，在新热带地区，没有以前的研究来研究不同水鸟物种在其执行的扩散功能中如何变化，以及季节性因素如何影响内分泌。在这项研究中，我们确定了分布在五个南美水禽（巴西蓝绿色亚马逊水鸭Amazonetta brasiliensis，黄嘴蓝绿色水鸭Anas flavirostris，环状蓝绿色水鸭Callonetta leucophrys，绿皮科天鹅天鹅Coscoroba coscoroba和白面吹哨的小鸭Dendrocygna）粪便中的植物渗漏。
2. 我们从巴西南部五个被牧场和稻田包围的湿地中收集了165份粪便样品，然后分离并测量了完整的种子和其他渗水孔。使用广义线性模型，我们测试了鸟类之间以及寒冷（4月至9月）和温暖（10月至3月）之间的水母丰度和分类学丰富度如何不同。我们还通过主坐标分析和方差的排列多元分析来分析水鸟组成的鸟类特异性和季节性变化。我们使用指标物种分析来确定哪些水生孢子物种区分了鸟类和季节。最后，我们测量了diaspore的长度，以分析水禽物种之间的diaspore分散大小的差异。
3. 我们发现从40个不同的植物种类2066个完好繁殖体，包括37个被子植物种子和Lycophyta的繁殖体（水韭CF 。最大值），蕨类植物（细叶满江红），和轮藻纲。所有粪便样本中至少有65％渗出。天然的两栖和紧急植物的孢子占优势。我们在寒冷时期发现了1,835个diaspore（来自33个分类单元），而在温暖时期只有231个（23个分类单元）。草种子Zizaniopsis bonariensis和莎草Rynchosporasp。是最丰富的分类单元 鸟类种类和季节之间的强相互作用是分类丰富度和水生孢子丰度变化的最重要预测因子。在水禽种类和季节之间，水生孢子的分类组成有所不同。指标物种分析确定了与特定鸟类物种和季节相关的12种植物类群。Coscoroba天鹅是我们研究中最大的身体物种，散布了较大比例（8.2％）的大（长度> 2 mm）种子。
4. 尽管有很大的重叠，但每种物种分散的植物仍存在重要差异，最小的（环状蓝绿色）和最大的（疣鼻天鹅）鸟类尤其不同。所有这五个水禽物种都分布在南美的广大地区，在这里我们证明了它们很可能是连接不同地理尺度上的湿地物种的重要植物媒介。以前，其中许多工厂都缺乏远距离扩散的机制。