GOODALE, E.; Univ. of Massachusetts, Amherst: The attraction of mixed-species flocking birds to the vocalizations of other species

Can playback be used to investigate the structure of a mixed-species bird flock community? I In this study, I played back the vocalizations of the two most frequent members of a large Sri Lankan flock system, the Orange-billed Babbler (Turdoides rufescens) and the Greater Racket-tailed Drongo (Dicrurus paradiseus), as well as a common species less often found in flocks, the Yellow-fronted Barbet (Megaflaima flavifrons). I hypothesized that other species would be most attracted to the babbler since this highly gregarious species fulfills all the criteria of being a nuclear species (in sensu Moynihan, Smithsonian Miscellaneous Collections, 1962), and may provide foraging benefits to other insectivores by beating up insects (neither the drongo, an aggressive sallying species, nor the frugivorous barbet would offer such advantages). To simulate a flock, I broadcast two species’ vocalizations simultaneously; there were seven treatments in total, including the different combinations of the three species, and a silent treatment. A trial started with a point count, followed by the 10 minute playback of a one minute recording of the species, followed by a point count, and each treatment was replicated 20 times at locations 300 meters apart. I analyzed which species were seen or heard approaching the speaker during playback, and whether the final point count was higher than the initial one. Preliminary analysis shows that flocking species were attracted both by the babbler and by the drongo. The results serve as evidence that the drongo is also a nuclear species and do not support the idea that species join flocks specifically to gain foraging benefits with the babbler.