Fruit-eating birds of a subtropical riparian forest relic in Argentina: fruit-handling methods and seed fate

Abstract

Fruit-handling methods by the most important fruit-eating birds of the Punta Lara riparian forest and seed fate were studied. Feeding experiments were conducted involving 5 species of birds (each one represented by an individual) and 12 species of ornithochorous plants (11 of them common at the Punta Lara forest) with fruits or seeds that showed ample variation in their morphological traits. Feeding behaviour and seed dispersal were also observed in the wild and several individuals were captured with mist nets. The mode of fruit handling and seed fate varied with the bird type. Larger seeds were regurgitated or destroyed by birds that swallow whole fruits and dropped by those that crush the fruits in their bills prior to consumption, while the small seeds were defecated. Pulp type, degree of adhesion of pulp to seed, and type of seed coating influenced seed dispersal ability. The results confirm that the bird’s role as frugivore and its quality as seed disperser, while influenced by avian behaviour and morphology, are heavily dependent on plant dispersal-related traits.