The pollinators of two species of columnar cacti on Curaco, Netherlands Antilles
Three species of columnar cacti (Stenocereus gri seus, Subpilocereus repandus, and Pilosocereus lan uginosus) are conspicuous elements of arid vegetation in northern Venezuela and several nearby islands induding Aruba, Bonaire, and Curacao. Stenocereus griseus and Subpilocereus repandus produce most of their flowers and fruits during the dry season (from January to September) on Curacao, Netherlands Antilles (Petit 1995). They provide food for several species of animals (especially bats and birds) during part of the dry season, when many other plant species are non-productive. The major pollinators of these self-incompatible cacti in Venezuela are the bats Leptonycteris curasoae and Glossophaga longirostris (Phyllostomidae) (Nassar 1991). An exhaustive census showed that bats of all species, induding L. curasoae and G. longirostris were threatened on Curagao (Petit 1995). Unidentified sphinx moths and two species of hummingbirds are other potential cactus pollinators on the island. In the Sonoran desert, all three groups are important pol linators of columnar cacti (T. Fleming, pers. comm.), and in most systems studied so far, bats are not exdusive pollinators of key plants. I determined the importance of moths, birds, and bats as pollinators of S. griseus and S. repandus pollination on Curacao because bats were expected to contribute significantly to cactus pollination, and evidence of their ecological importance was needed to prompt conservation action for bats and caves.