title: Decay of interspecific avian flock networks along a disturbance gradient in Amazonia.
abstract: Our understanding of how anthropogenic habitat change shapes species interactions is in its infancy. This is in large part because analytical approaches such as network theory have only recently been applied to characterize complex community dynamics. Network models are a powerful tool for quantifying how ecological interactions are affected by habitat modification because they provide metrics that quantify community structure and function. Here, we examine how large-scale habitat alteration has affected ecological interactions among mixed-species flocking birds in Amazonian rainforest. These flocks provide a model system for investigating how habitat heterogeneity influences non-trophic interactions and the subsequent social structure of forest-dependent mixed-species bird flocks. We analyse 21 flock interaction networks throughout a mosaic of primary forest, fragments of varying sizes and secondary forest (SF) at the Biological Dynamics of Forest Fragments Project in central Amazonian Brazil. Habitat type had a strong effect on network structure at the levels of both species and flock. Frequency of associations among species, as summarized by weighted degree, declined with increasing levels of forest fragmentation and SF. At the flock level, clustering coefficients and overall attendance positively correlated with mean vegetation height, indicating a strong effect of habitat structure on flock cohesion and stability. Prior research has shown that trophic interactions are often resilient to large-scale changes in habitat structure because species are ecologically redundant. By contrast, our results suggest that behavioural interactions and the structure of non-trophic networks are highly sensitive to environmental change. Thus, a more nuanced, system-by-system approach may be needed when thinking about the resiliency of ecological networks.
authors: School of Renewable Natural Resources, Louisiana State University Agricultural Center, , 227 RNR Building, LSU, Baton Rouge, LA 70803-6202, USA, Projeto Dinâmica Biológica de Fragmentos Florestais, INPA, , R. André Araújo 2936, Caixa postal 478, Petrópolis, Manaus, Amazonas 69083-000, Brazil, Smithsonian Conservation Biology Institute, , National Zoological Park, PO Box 37012-MRC 5503, Washington, DC 20013, USA, Departamento de Ecologia, Universidade Estadual Paulista, , Rio Claro, São Paulo 13506-900, Brazil.
authors: Karl
authors: K
authors: Mokross
authors: Thomas B
authors: TB
authors: Ryder
authors: Marina Corrêa
authors: MC
authors: Côrtes
authors: Jared D
authors: JD
authors: Wolfe
authors: Philip C
authors: PC
authors: Stouffer
mesh_terms: D063147:Animal Distribution / Q000502:physiology*; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D001717:Birds / Q000502:physiology*; D001938:Brazil; D017753:Ecosystem; D004777:Environment; D008954:Models, Biological; D013045:Species Specificity; D014197:Trees
keywords: Amazon; forest fragmentation; heterogeneous landscapes; insectivorous birds; mixed-species flocks; network theory