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...