Microhabitat associations of terrestrial insectivorous birds in Amazonian rainforest and second-growth forests

Document Type

Article

Publication Date

1-1-2013

Abstract

Across the Neotropics, small-bodied terrestrial insectivores are sensitive to forest fragmentation and are largely absent from second-growth forests. Despite their sensitivity to forest structure, the microhabitat relationships of these birds have not been quantified. From July 1994 to January 1995 in central Amazonia, we characterized habitat at sites where nine species of terrestrial insectivores were observed foraging, as well as at randomly selected sites in continuous forest and two types of 10-15-yr-old second-growth forest common in Amazonia (Vismia- and Cecropia-dominated). We used factor analysis to find suites of correlated variables. From each factor, we selected a representative variable that was relatively easy to measure. We used Bayesian analysis to estimate means and standard deviations of these variables for each species and for each type of habitat. All nine focal species were associated with ranges of microhabitat variables, such as leaf litter depth and tree densities, often absent in second-growth forests. At least in the early stages of regeneration, neither type of second-growth forest provides suitable structure for the terrestrial insectivores in our study. The large leaves of Cecropia trees that make up the thick leaf litter may preclude the use of Cecropia-dominated second growth by our focal species, many of which manipulate leaves when foraging. The leaf litter in Vismia-dominated second growth was also thicker than sites used for foraging by our focal species. In addition, Vismia-dominated growth had more small trees and small nonwoody vegetation, perhaps impeding movement by terrestrial birds. In continuous forest, our focal species foraged in microhabitats with characteristics that generally overlapped those of randomly selected sites. Thus, our results are consistent with the hypothesis that microhabitat differences make second-growth forests unsuitable for our focal species. © 2013 The Authors. Journal of Field Ornithology © 2013 Association of Field Ornithologists.

Publication Source (Journal or Book title)

Journal of Field Ornithology

First Page

1

Last Page

12

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