ABSTRACT The family Cactaceae possesses considerable floral diversity and is exclusively zoophilic. Cipocereus crassisepalus is an endangered species of columnar cactus, whose floral characteristics fit the chiropterophily syndrome. This study aimed to assess the correspondence between floral traits and pollinators and whether the pollination system of C. crassisepalus is specialized, as suggested by the hypothesis of geographical dichotomy. Hand pollination treatments demonstrated that C. crassisepalus depends on cross-pollen flow mediated by pollinators to set fruit and seeds. Nocturnal film recordings, diurnal observations, analyses of pollen loads of flower visitors and visitor exclusion experiments provided strong evidence that bats are the sole pollinators of this cactus. During two flowering seasons, pollen grains of C. crassisepalus were found only on the bodies of the bat Anoura caudifer. Cipocereus crassisepalus possesses a pollination system specialized on nectar-feeding bats, which corroborates the geographical dichotomy hypothesis.

ABSTRACT During flight, hummingbirds achieve the maximum aerobic metabolism rates within vertebrates. To meet such demands, these birds have to take in as much energy as possible, using strategies such as selecting the best food resources and adopting behaviors that allow the greatest energy gains. We tested whether hummingbirds choose sources that have higher sugar concentrations, and investigated their behaviors near and at food resources. The study was conducted at Atlantic forest remnant in Brazil, between June and December 2012. Four patches were provided with artificial feeders, containing sucrose solutions at concentrations of 5%, 15%, 25% and 35% weight/volume. Hummingbird behaviors were recorded using the ad libitum method with continuous recording of behaviors. The following species were observed: the Brazilian ruby Clytolaema rubricauda (Boddaert, 1783), Violet-capped woodnymph Thalurania glaucopis (Gmelin, 1788), Scale-throated hermit Phaethornis eurynome (Lesson, 1832), White-throated hummingbird Leucochloris albicollis (Vieillot, 1818), Versicoloured emerald Amazilia versicolor (Vieillot, 1818), Glittering-bellied emerald Chlorostilbon lucidus (Shaw, 1812) and other Phaethornis spp. C. rubricauda, P. eurynome and Phaethornis spp. visited the 35%-sucrose feeders more often, while the T. glaucopis visited the 25%-sucrose feeders more often. L. albicollis and A. versicolor visited more often solutions with sugar concentration of 15%. C. lucidus visited all patches equally. Three behavioral strategies were observed: 1) C. rubricauda and T. glaucopis exhibited interspecific and intraspecific dominance; 2) the remaining species exhibited subordinance to the dominant hummingbirds, and 3) P. eurynome and Phaethornis spp. adopted a hide-and-wait strategy to the dominant hummingbird species. The frequency of aggressive behaviors was correlated with the time the hummingbird spent feeding, and bird size. Our results showed that hummingbirds can adopt different strategies to enhance food acquisition; that more aggressive species feeding more than less aggressive species; and that the birds, especially if they were dominant species, visited high quality food resources more often.