Abstract We hypothesize that the presence of cattle should increase environmental heterogeneity and therefore maintain more diverse bird communities. Therefore, we analyzed the changes in the structure of vegetation and diversity of bird species that inhabit the fluvial forests in the Delta region of the Parana River in relation to the different cattle raising management (islands with cattle, islands without cattle, islands with recent cattle exclusion). In the islands with cattle we found lower height of the herbaceous layer, less coverage of the shrub layer and lower presence of climbing plants, which were associated with birds assemblages with greater richness, abundance and diversity. We consider that this region has evolved under a context of significant herbivory pressure, which in pre-Columbian times was possibly dominated by Blastocerus dichotomus and Ozotoceros bezoarticus (locally extinct at present), Hydrochoerus hydrochaeris and Myocastor coypus. In this context, the complete exclusion of cattle in protected areas and the absence of the cervids that inhabited this region in the past, would lead to deterioration the natural condition of the environment and seems to be generating a decrease in the diversity of these sites. We consider that a reintroduction plan for these cervids should be implemented in the area.

中文翻译：

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养牛如何影响巴拉那河三角洲的鸟类群落？

摘要我们假设牛的存在应该增加环境异质性，从而维持更多样化的鸟类群落。因此，我们分析了巴拉那河三角洲地区河流森林植被结构和鸟类多样性与不同养牛管理（有牛的岛屿、无牛的岛屿、最近有牛的岛屿）相关的变化。排除）。在有牛的岛屿中，我们发现草本层的高度较低，灌木层的覆盖率较低，攀缘植物的存在较少，这与更丰富、丰富和多样性的鸟类组合有关。我们认为该地区是在巨大的食草压力背景下进化的，在前哥伦布时代，可能以 Blastocerus dichotomus 和 Ozotoceros bezoarticus（目前在当地已灭绝）、Hydrochoerus hydrochaeris 和 Myocastor coypus 为主。在这种情况下，在保护区完全排除牛以及过去栖息在该地区的鹿科动物将导致环境的自然条件恶化，并似乎导致这些地点的多样性下降。我们认为应该在该地区实施这些鹿科动物的重新引入计划。会导致环境的自然条件恶化，并且似乎导致这些地点的多样性减少。我们认为应该在该地区实施这些鹿科动物的重新引入计划。会导致环境的自然条件恶化，并且似乎导致这些地点的多样性减少。我们认为应该在该地区实施这些鹿科动物的重新引入计划。