Wild birds, humans work together to find bees' honey in Africa: study

When it comes to human-animal collaboration, you might think of dogs, falcons or cormorants that are domesticated or trained by their owners to hunt prey.

But in some parts of Africa, a species of wild bird called honeyguides and humans have learned to "talk" to each other for finding wild bees' nests which provide food to them both, research published this week in the U.S. journal Science revealed.

It has been known for centuries honeyguides can give a special call to attract people's attention, then fly from tree to tree to indicate where bee hives are hidden above.

Then, humans subdue stinging bees with smoke, chop open their nest and harvest the honey for themselves, while leaving the wax behind for the birds.

In the new study, researchers found that humans can also solicit the help of honeyguides through special calls, which the birds are able to recognize and respond to, resulting in a two-way communication.

"What's remarkable about the honeyguide-human relationship is that it involves free-living wild animals whose interactions with humans have probably evolved through natural selection, probably over the course of hundreds of thousands of years," said study author Claire Spottiswoode, an evolutionary biologist at the University of Cambridge and University of Cape Town.

This reciprocal relationship was first recorded in print in 1588 by Joao dos Santos, a Portuguese missionary working in what is now Mozambique.

Now, Spottiswoode and colleagues interviewed 20 honey-hunters from the Yao tribe in the southeast African country, who use a distinctive call which they believe helps them to recruit honeyguides.

The "honey-hunting call," which the Yao men said they learned from their fathers, is a loud trill followed by a short grunt, "brrr-hm."

To confirm the efficacy of this mutualistic relationship, as well as the call itself, the researchers trailed honey-hunters and found that 75 percent of guiding events led to the successful discovery by humans of at least one bees' nest.

Next, to test whether honeyguides associate "brrr-hm" with a specific meaning, they made recordings of this call and two kinds of "control" sounds: arbitrary words called out by the honey-hunters and the calls of another bird species.

When these sounds were played back in the wild during experimental honey-hunting trips, birds were much more likely to respond to the "brrr-hm" call made to attract them than they were to either of the other sounds.

The traditional "brrr-hm" call increased the probability of being guided by a honeyguide from 33 percent to 66 percent, and the overall probability of being shown a bees' nest from 16 percent to 54 percent compared to the control sounds, it found.

In other words, the "brrr-hm" call more than tripled the chances of a successful interaction, yielding honey for the humans and wax for the bird.

Honeyguides are widely found in sub-Saharan Africa, and people in other parts of Africa use very different sounds for the same purpose. For example, Hadza honey-hunters in Tanzania can make a melodious whistling sound to recruit them.

"We'd love to know whether honeyguides have learnt this language-like variation in human signals across Africa, allowing them to recognize good collaborators among the local people living alongside them," Spottiswoode added. Enditem