Bird Use of Epiphyte Resources in Neotropical Trees

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Abstract
Epiphytes are a common component of neotropical forests, but their importance to birds at the community level and their role in contributing to tropical bird diversity has only rarely been considered. Literature accounts from 55 studies document 193 species of neotropical birds that take nectar, fruits, invertebrates, water, and nesting materials from epiphytes. To quantify the amounts and types of resources provided by epiphytes compared to host trees, we watched birds in 14 forest and pasture sites (1,350-1,420 m) for 2 months in a lower montane landscape of Costa Rica. During our 289 hr of observations from within the canopy and on the ground, 33 of 56 bird species observed in foraging visits foraged in resources provided by epiphytes. Epiphyte resources were involved in 32% of all foraging visits. For eight bird species, 40% or more of all foraging visits involved epiphyte use, which included foraging for fruits, nectar, invertebrates, water, and nesting materials. Six types of bird foraging behaviors in six types of epiphytes are described and compared to bird use of tree resources. Some birds appeared to specialize on particular epiphyte resources such as invertebrates in crown humus. The frequent epiphyte use by a large number of bird species indicates that epiphytes constitute a resource that has generally been overlooked in past bird community studies. We discuss two ways that epiphytes may contribute to high tropical bird species diversity.