Data from: What can mixed-species flock movement tell us about the value of Amazonian secondary forests? insights from spatial behavior

The value of secondary forest for rainforest species remains an important question for conservation in the 21st century. Here, we describe the spatial behavior of understory mixed-species flocks in a heterogeneous landscape in central Amazonia. Understory mixed-species flocks represent a diverse, highly organized component of the rich Amazonian avifauna. We recorded movements within 26 flock home ranges in primary forest, secondary forest, interfaces between forest types, and forest fragments. We describe frequency and movement orientation in relation to forest edges, movement patterns and proportion of use between secondary and primary forest, the relation between home range sizes and vegetation height, and home range configuration. Flocks visited only a small portion of forest edges, and showed a tendency for moving parallel to edges next to less-developed secondary forest. Movement patterns in secondary forests did not show significant differences compared to primary forests. Time spent in secondary forests increased in proportion to mean canopy height. Flocks were consistently present in secondary forests where vegetation height averaged over 15 m, but home ranges were nearly twice as large compared to primary forest. Home range limits tended to be aligned with disturbed vegetation, essentially rearranging a territorial configuration normally adjusted by topography. The spatial behavior of this important subset of the Amazonian avifauna shows that secondary forests are tolerated above a certain development threshold, but perceived as sub optimal habitat until canopy height closely matches primary forests.21世纪的生物保护领域中，次生林（secondary forest）对于雨林物种的保育价值仍是一个核心议题。本研究针对亚马孙中部异质景观中的林下混合鸟群（understory mixed-species flocks）的空间行为展开系统性描述。林下混合鸟群是亚马孙丰富鸟类区系中兼具物种多样性与高度组织性的重要组成部分。我们记录了26个鸟群家域（home range）内的活动轨迹，这些家域覆盖原生林（primary forest）、次生林、林型交界带以及森林片段生境。本研究分析了鸟群与林缘相关的活动频率与移动方向、次生林与原生林的利用比例与移动模式、家域面积与植被高度的关联，以及家域布局特征。研究发现，鸟群仅会利用极小部分林缘区域，且在发育程度较低的次生林周边时，倾向于沿林缘平行方向移动；次生林内的鸟群移动模式与原生林无显著差异。鸟群在次生林中的停留时长与平均冠层高度（canopy height）呈正相关增长。当次生林植被平均高度超过15米时，鸟群会持续停留于此，但此时的家域面积相较原生林几乎扩大了一倍。家域边界往往与受干扰植被带重合，本质上是对原本由地形调控的领地布局进行了重新排布。亚马孙鸟类区系中这一重要类群的空间行为表明，次生林只有达到特定发育阈值后才会被鸟群接纳，而在冠层高度未完全匹配原生林之前，次生林始终会被视为次优生境。