Seed dispersal by bats and birds in forest and disturbed habitats of Chiapas, Mexico

We examined seed dispersal by bats and birds in four habitats of the Selva Lacandona tropical rain forest region, Chiapas, Mexico. The four habitats r epresented a disturbance gradient: active cornfield, ten-year-old abandoned cornfield, cacao plantation, and forest. Using seed traps examined before sunrise (0400 h) and before sunset (1800 h), we compared volant vertebrate seed dispersal, assuming that seeds found at the end of the night were disp ersed by bats and those found at the end of the day were dispersed by birds . We did not find seeds from other frugivores such as monkeys or opossums. In all habitats bats dispersed more seeds than birds. In most months bats a lso dispersed more seeds than birds, except in December when no seeds were found in the traps. Bats also consistently dispersed more species of seeds than birds, although a chi(2) comparison showed differences not to be signi ficant. Fifty percent of the species represented in the dispersed seeds in all habitats were pioneer species. Cecropia seeds represented a high percen tage (up to 87% of those dispersed by bats and up to 83% by birds) of dispe rsed seeds that fell in our traps. The influence of bats and birds on secon dary successional processes is likely to be fundamental for the establishme nt of vegetation. Since bats dispersed more seeds than birds (primarily to disturbed areas and consisting primarily of pioneer species), they are like ly to play an important role in successional and restoration processes amon g habitats as structurally and vegetationally different as cornfields, old fields, cacao plantations, and forest.