Bat-pollinated flower assemblages and bat visitors at two Atlantic forest sites in Brazil

Abstract

A comparison between bat-pollinated plant assemblages at two sits in different altitudinal ranges covered by the Atlantic rainforest in southeastern Brazil is presented. The lowlands (5-90 m) harbour ten plant species in seven families, pollinated mostly by three glossophagine bat species. The highlands (1540-1600 m) harbour seven plant species in five families, pollinated by a single species of glossophagine. Bromeliads account for about 30 % of the bat-pollinated species at each assemblage. Tube and brush shapes prevail in the flowers at both sites. Corolla lengths averaged 26.8 and 37.2 mm, sugar concentrations in nectar averaged 15.0 and 18.0%, and nectar volumes averaged 150.8 and 167.0 μl in the lowland and highland assemblages, respectively. The flowers are pollinated mostly by glossophagine bats during hovering visits, and the plants are visited in the trap-line foraging pattern. The plants bloom annually and both assemblages show a staggered continual flowering pattern. Flowering seasonality was found at both sites, with flowering clustering in the drier season at the lowland site and in the wetter season at the highland site. The ratio between bat-pollinated and hummingbird-pollinated species is 0.24 at the lowland site and 0.23 at the highland one. These similar values indicate that additional studies on bat- and bird-pollinated assemblages are merited at other Atlantic rainforest sites.