Echolocation, olfaction and fruit display: how bats find fruit of flagellichorous cucurbits

1. The relationship between plant morphology and the senses used by dispersal agents to find fruit was examined. ‘Flagellichory’ (fruit borne on pendulous structures), a costly morphology associated with dispersal by bats, is focused on.

2. Using Gurania spinulosa, a flagellichorous vine, and its major dispersal agent, Phyllostomus hastatus, the hypothesis was tested that flagellichory increases the conspicuousness of fruit to bats that use echolocation to find fruit.

3. The responses of wild-caught P. hastatus to various fruiting branch morphologies and fruit odour were recorded. Phyllostomus hastatus used echolocation rather than olfaction to detect fruit, and consistently chose fruit displayed on pendulous leafless branches, ignoring fruit held among leaves on horizontal branches.

4. By comparing echolocation signals with the distance between fruiting branches of G. spinulosa and surrounding vegetation, it was shown that pendulous fruiting branches present clear, clutter-free targets that can be detected by echolocating bats. This is the first demonstration of neotropical frugivorous bats using echolocation to find fruit.