Vocal coordination of group movement by green woodhoopoes (Phoeniculus purpureus)

Communication signals are used by many species to maintain group cohesion when moving over larger areas. Groups of green woodhoopoes (Phoeniculus purpureus) generally move around their territory as a close-knit unit. Dominant individuals were more likely than subordinates to initiate movement to a new foraging site, but there was no intersexual difference. Dominants were also more likely than subordinates to be followed immediately. Vocalizations were shown to play an important role in mobilization: in the thick forests inhabited by woodhoopoes, visual cues to coordinate movement are likely to be less successful. When responding to the rallying call of a neighboring group, dominants and subordinates were equally likely to lead, as were males and females. As other group members followed immediately on most of these occasions, vocalizations were less important in this context than when moving to a new foraging site.