THE EFFECT OF BAT (ROUSETTUS-AEGYPTIACUS) DISPERSAL ON SEED-GERMINATION IN EASTERN MEDITERRANEAN HABITATS

The fruit-bat Rousettus aegyptiacus (Pteropodidae) in Israel consumes a variety of cultivated and wild fruits. The aim of this study was to explore some of its qualities as a dispersal agent for six fruit-beari ng plant species. The feeding roosts of the fruit-bat are located an a verage of 30 m from its feeding trees and thus the bats disperse the s eeds away from the shade of the parent canopy. The bat spits out large seeds but may pass some (2%) of the small seeds (<4 mg) through its d igestive tract. However, neither the deposited seeds nor the ejected s eeds (except in one case) had a significantly higher percentage germin ating than intact seeds. Although the fruit-bat did not increase the p ercentage germinating, seeds of three plant species subject to differe nt feeding behaviors (deposited in feces or spat out as ejecta) had a different temporal pattern of germination from the intact seeds. The c ombined seed germination distribution generated by these different tre atments is more even over time than for each treatment alone. It is su ggested that this increases asynchronous germination and therefore enh ances plant fitness by spreading the risks encountered during germinat ion, especially in eastern Mediterranean habitats where the pattern of rainfall is unpredictable.