Psarocolius decumanus(Icteridae) acts as a seedling disperser ofGomesa recurva(Orchidaceae) in the Brazilian Atlantic Forest

Abstract

AbstractPsarocolius decumanus(crested oropendola) (Icteridae) is a neotropical bird whose reproductive biology is well studied. Its nests consist of pendulous bags up to 2‐m long usually made ofTillandsia usneoides(Bromeliaceae) with dry leaves lining up the incubation chamber. Several materials from different botanical families have been reported in the nests of crested oropendolas. However, these other plants have not been recognized at the specific level. In the present study, we report the use of roots and pseudobulbs ofGomesa recurva(Orchidaceae) by crested oropendolas to build nests in strictly protected area in the Brazilian Atlantic Forest. The roots ofG. recurvaare fibrous, eventually intertwined and reach tens of centimetres, constituting a suitable material for building nests. This interaction could also be beneficial for the orchid, because when searching for roots and pulling them out, the birds end up taking with them also small pseudobulbs. When building the nest with these parts ofG. recurva, crested oropendolas promote the dispersal of the orchid throughout the area. Seedlings may occasionally get attached to the lower branches and grow at more basal strata of the phorophytes or as terricolous in the forest understory after nests fall. In addition, as the nests are always built in the upper strata of trees, crested oropendolas may also be improving plant performance since many orchid species need relatively high light environments to bloom. The relationship betweenP. decumanusandG. recurvaand the ecological conditions required by both species need to be better investigated in future studies.