The Relation of Foliage Complexity to Ecological Diversity of Three Amazonian Bird Communities

Abstract

The relation between the complexity of the foliage and the structure of the bird community was compared on 3 Amazonian forest plots [Ecuador, Peru, Bolivia] of similar foliage complexity. Predictions made by assuming equilibrium numbers of species in relation to foliage profile were not supported and expected correlations between foliage complexity and numbers of bird species were not found. Correlations between total number of individuals and total biomass, however, were found. Similar proportions of individual birds on each plot used the same foraging technique. In corresponding vertical strata, there was a significant correlation between the rank order of number of bird individuals using a specific foraging technique on each plot. The vertical biomass distribution was different on the 3 plots and different degrees of interclass competition was a possible explanation for the difference in bird biomass in the upper strata. The overall structure of the bird communities on the plots was mediated by a combination of structural and energetic limitations inherent in the foliage, historical patterns of foliage and bird distribution and competitive interactions among the birds and with other animals, especially monkeys.