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RESPONSES OF UNDERSTORY BIRDS TO ANTHROPOGENIC EDGES IN A NEOTROPICAL MONTANE FOREST
Author(s) -
Restrepo Carla,
Gómez Natalia
Publication year - 1998
Publication title -
ecological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.864
H-Index - 213
eISSN - 1939-5582
pISSN - 1051-0761
DOI - 10.1890/1051-0761(1998)008[0170:roubta]2.0.co;2
Subject(s) - understory , montane ecology , ecology , geography , cloud forest , biodiversity , agroforestry , biology , canopy
In a Neotropical montane forest in southwestern Colombia, we investigated how the distribution of understory birds changed from forest edge to forest interior (0–10 m, 30–40 m, 60–70 m, and 190–200 m from the edge) and how these changes were influenced by edge age (three old [>40 yr] and three young [<12 yr] edges) and month sampled. Capture rates of frugivores were highest both at the forest edge (0–10 m) and forest interior (190–200 m); for insectivores, capture rates were highest at the forest interior; for nectarivores, they were highest at the forest edge. Distance, edge age, and month interacted in various ways. Frugivores were more abundant at the forest interior than at the edge during the dry months. Insectivores were more abundant at new edges than at old edges during the wet months. Seventeen out of 25 abundant species (≥21 captures), including the Tangara spp. assemblage, exhibited a non‐uniform distribution, showing either an increase or decrease from forest edge to forest interior, or bimodal distributions. Extremely sparse species (one capture) were found more often than expected near the forest edge (0–10 m). Edges resulting from large‐scale, anthropogenic disturbances influenced the distribution of understory birds in complex ways. Significant interactions between distance, month, and edge age suggest that “edge effects” change over various temporal scales. Instead of emphasizing “depth” of “edge effects,” future studies should emphasize edge dynamics, i.e., how processes taking place at edges change over time, and how organisms can modify any “edge effect.” In particular, changes in the distribution of frugivores suggest that seed dispersal may be influenced by the presence of edges, leading to changes in the structure and location of edges through time. This might be particularly true in our study area, where transient corn fields, pastures, and second‐growth areas of various ages are embedded in a forest matrix.