Investigating polyspecific communication and associations between primates and birds in Madagascar

Some species in co-evolved communities may rely on others to access resources or avoid predation, with knock-on effects for their survival if the dynamics of mixed species groups or interspecific communication are changed. Madagascar has some particularly vulnerable ecosystems and habitat fragmentation threatens the survival of lemurs and other animals. It is therefore essential that we understand the complex relationships between different species. This study investigated whether ring-tailed lemurs, Lemur catta, and Verreaux’s sifakas, Propithecus verreauxi, respond to specific bird calls, and if so, what is the function and habitat context of these responses. Whilst both are known to recognise each others’ alarm calls and the calls of aerial predators, this is the first time that an experiment has tested their responses to non-predator bird alarm calls. The second half of the study explored whether these two species form associations with specific bird species, and the function of any associations formed. A controlled playback experiment was used to test responses of the two lemur species to the following bird calls in different habitats: song of Madagascar magpie robin, Copsychus albospecularis, (control), green pigeon, Treron australis, song, white-headed vanga, Artamella viridi, call and crested drongo, Dicrurus forficatus, alarm call. The research was carried out at Berenty reserve in the south of Madagascar. Calls were presented in counterbalanced order to 21 different troops of lemurs. Group scans recorded lemur behaviour prior to and after playback. Focal sampling and group scans were used to record activity, habitat context and bird associations for each troop. Both lemur species showed a significantly greater vigilant response to crested drongo alarm calls compared to their response to the control. Open and closed habitat did not have a significant effect on either species of lemurs’ response to the crested drongo alarm calls. Neither lemur species were shown to seek out associations with specific bird species. The results suggest that the primary reason for these two lemur species listening to bird communication is predation avoidance rather than foraging efficiency. This research supports the suggestion that species in co-evolved communities may rely on others to avoid predation.