In sub-Saharan Africa, some communities work together with wild birds to find honey. Using distinctive calls, honey-hunting people coordinate with greater honeyguides (Indicator indicator), who lead them to bee hives. A new study demonstrates that the honey-hunters’ calls vary between communities, and evolve in much the same way as human dialects.
Honey-hunters use two call types to communicate with honeyguides: recruitment calls to invite the wild birds to the hunt, and coordination calls to stay in contact with the bird as it leads them to a hive.
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Once a hive has been located, honey-hunters use smoke to subdue the bees and harvest their honey, while the honeyguides help themselves to beeswax and tasty grubs.
Both species therefore benefit from this interaction: honeyguides get food that they couldn’t otherwise access, and honey-hunters are guided to the hive. Indeed, previous research shows that honey-hunters are over three times more likely to find a hive if they have a honeyguide guiding them.
Both types of call that the honey-hunters use – recruitment and coordination – vary across cultures, in the same way that human language varies. But even neighbouring villages have slightly different calls, a bit like regional dialects.
To find out if these ‘dialects’ evolved because of cultural processes, like human language dialects do, researchers recorded calls from 131 honey-hunters across 13 villages in Mozambique’s Niassa Special Reserve.
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They found that neighbouring villages tended to have similar calls, while villages that were further apart had more dissimilar calls. Meanwhile, environmental factors had no effect on call similarity. This means that call variation is driven by cultural rather than environmental processes.
“The highlights just how powerfully culture shapes us as a species, even in our interactions with wild, untrained animals,” explains Dr Jessica Van Der Wal, lead author of the study.
While honey-hunters learn recruitment and coordination calls from their fathers, scientists are unsure how honeyguides learn to cooperate with humans.
“They can’t learn from their parents, because they are brood parasites: like cuckoos, they lay their eggs in other birds’ nests,” says Dr Van Der Wal. “But they may learn by observing other honeyguides interacting with humans.”
Senior author Professor Claire Spottiswoode, of the University of Cape Town’s FitzPatrick Institute of African Ornithology (who leads the Honeyguide Research Project), added “Humans learn and maintain the local signals needed to cooperate with honeyguides, and honeyguides are in turn probably learning and so helping to reinforce these local human dialects – much as they learn larger-scale variation in human signals across Africa, more akin to different human languages.”
Figuring out how honeyguides learn to cooperate with humans is one of the team’s next research questions.
Top image: Carvalho Nanguar, a Yao honey-hunter from northern Mozambique, with a male greater honeyguide. Credit: David Lloyd-Jones and Dominic Cram
