Aves consumidoras de sementes de bambus dos gêneros Guadua sp. e Merostachys sp. na Mata Atlântica do Estado do Rio de Janeiro, Brasil

Abstract

Bamboos are usually semelparus, long life, with its unique fruiting synchronously between all individuals in the same region, occurring at fixed intervals, species-specific, ranging from three to 120 years. According to Satiation of Predators Hypothesis, bamboo accumulate biomass throughout life, and invest this biomass into a single, explosive fruiting. The large synchronic production of seeds among many individuals would be enough to satisfy the seed predators and produce a surplus that can guarantee the new generation. The main assumptions of this hypothesis are: (1) Bamboo seeds are predated by a large number of granivores, causing a great pressure of predation; (2) Small resident species are the main predators, as their populations increase in response to the abundance of food. We observed the birds consuming seeds of the Atlantic Forest endemic bamboo Guadua tagoara over 89 field days, divided in 10 years and 16 locations. We also observed the consumers birds present in fruiting individuals of two bamboos species of the genus Merostachys, over 11 field days. We found a small number of species of birds consuming seeds of both bamboos and nomadic species predominating among consumers species, against the two main premises of Satiation of Predator Hypothesis. In Merostachys, which had a greater interval between following fruitings, greater synchronization and shorter duration of fruiting, we have found only nomadic birds and fewer species of birds consuming compared to G. tagoara. We suggest that the long intervals between fruitings and synchronization can be a reproductive strategy to prevent resident birds to be adapted to identify the seeds of bamboo as food.