Bamboo specialist birds of the Neotropics: focus on the Atlantic forest, a hotspot for bamboo specialists

ARETA, JUAN I; COCKLE, KRISTINA

Campos do Jordão, Brasil

Simposio; International Ornithological Congress; 2010

Although bamboos occur in many regions, most birds that specialize on bamboo seem to occur in the Neotropics. Specialization on bamboo seeds, shoots and insects, has arisen in at least 15 families of Neotropical birds. The Atlantic forest region is a hotspot for bamboo specialist birds, with 13 species occurring in the Atlantic forest of Argentina. We predict the abundance and distribution of these species to vary quasi-cyclically over time, in response to the availability of their preferred bamboo resources, which depend on the deep-time dynamics of changing bamboo flowering overlap. Specialists on seeds of Guadua, like Temminck’s Seedeater (Sporophila falcirostris), which has the lower mandible much thicker than the upper mandible, occur in Argentina every ~15 years when one of the two Guadua seeds. The Uniform Finch (Haplospiza unicolor) with a thinner, conical bill, also exploits Guadua seeds but has a broader niche, feeding primarily on Chusquea ramosissima seeds, which are always available somewhere in the region. The Blackish-blue Seedeater (Amaurospiza moesta) apparently feeds primarily on green bamboo matter, and secondarily upon seeds, especially in Merostachys bamboo; we do not expect large population fluctuations. The White-bearded Antshrike (Biatas nigropectus) is an insectivore almost always found in Guadua trinii; we predict its populations to increase over the vegetative phase of G. trinii, but decline sharply when it dies after flowering en masse. The most specialized bamboo-users like S. falcirostris, B. nigropectus and the Purple-winged Ground Dove (Claravis godefrida) should experience the largest population fluctuations and be the most vulnerable to stochastic extinction.