Humans and wild animals often help each other, but the relationship is usually accidental. For example, birds of prey sometimes follow farm equipment through fields because the hardware washes away small animals. People don’t intentionally help the birds and we gain nothing. For truly cooperative relationships, you generally have to look at animals we’ve domesticated.
In general, but not exclusively. There is an African bird called the honeyguide that helps people find bee nests. The humans get the honey, while the birds feast on the leftover wax (the honey guides were first formally described after witnessing them eat some candles). Now, new research shows that the birds may respond specifically when a human calls to indicate their interest in finding honey.
Honeyguides inhabit a part of Africa that includes Tanzania and Mozambique. When they feel like beeswax, they approach a human and start chattering. This call differs from the one they use to communicate with each other, and involves very specific behavior: the bird flits from tree to tree in the general direction of a bee’s nest. Once the nest is found and opened, the human gets away with honey, leaving the wax for the honeyguide to eat.
It is an extremely effective mutualism. Once the guidance process began, the researchers found that three-quarters of searches ended in the discovery of a bee’s nest.
The people who collect honey in the area where honey guides live have their own call to indicate when they are ready to hunt. Researchers describe it as “a loud trill followed by a growl: ‘brrrr-hm.'” The honeyhunters told the researchers that they learned this call socially — their parents or other relatives usually taught it to them. So the researchers decided to test whether it was effective.
To do this, the researchers recorded the call, along with two controls: humans uttering the local word for honey guide and another bird’s call. They played these through speakers and recorded what happened next (which you’ll probably believe and if not, there’s data). The “let’s go find honey” call attracted a honeyguide two-thirds of the time, while the control sounds only attracted one at about half that frequency.
But even when honeyguides responded to the two control sounds, they tended to quickly give up on the search. Only about 15 percent of searches that started with the control sounds resulted in the discovery of bee nests, while more than half of the searches that started with the correct call ended in honey.
What is striking about this research is that there is nothing special about the call. In other parts of Africa, completely different sounds are used to attract honeyguides. Birds learn a lot of non-instinctual behavior from their parents, but that can’t be the case here. Honeyguides are parasites, laying their eggs in the nests of other bird species which then raise their young.
The authors suspect that honeyguides learn to heed the call by observing the success of their peers. Young honeyguides, who look a bit different, are mistaken for a different species by the people who collect honey, largely because they don’t respond to people’s calls for help.
While there are anecdotal reports of humans calling wild dolphins for a mutually beneficial search for food, this new study is the first time this type of behavior has been described in this kind of detail. And it happens in a species that has nothing like the mental horsepower of a dolphin.
Science2016. DOI: 10.1126/science.aaf4885 (About DOIs).