Among songbirds, complex vocal learners are superior problem solvers

Many songbirds can learn an amazing repertoire of warbles, whistles, calls, and songs during their lives. Among them, European starlings rank among the most advanced avian vocal learners. 

Now, a team of researchers led by Rockefeller University has found that starlings and other complex vocal learners are also superior problem solvers, demonstrating advanced cognitive skills.

Focus of the study 

“There is a long-standing hypothesis that only the most intelligent animals are capable of complex vocal learning,” said lead author Jean-Nicolas Audet, a behavioral ecologist at Rockefeller. 

“If that is true, then complex vocal learners should also be better at cognitive tasks, but no one had ever demonstrated that before.”

Vocal learning

Only a few animal groups are capable of complex vocal learning, defined as the ability to learn and remember a large repertoire of sounds. 

While humans, elephants, seals, whales, and bats represent most mammalian vocal learners, songbirds, parrots, and hummingbirds are the most advanced avian vocal learners. 

How the research was conducted 

For the present study, the experts focused on songbirds, ranking their vocal learning complexity across three metrics: how many songs and calls are in their repertoire, whether they can continue to learn new songs and calls during their lives, and whether they can mimic other species.

To determine whether vocal learning abilities are associated to different cognitive skills, the researchers spent three years catching hundreds of wild songbirds from 21 species in mist nets at the Rockefeller University Field Research Center, a vast 1,200 protected acres of land comprising many different ecosystems in New York’s Hudson Valley.

“It’s a protected area, which means the animals have limited exposure to humans,” said co-author Mélanie Couture, a doctoral student in Computational and Systems Neuroscience at Rockefeller. “This is ideal for studying the behaviors of wild birds – what they can do, and how they react to cognitive tasks.”

What the researchers learned 

The examination revealed that three species – starlings, blue jays, and gray catbirds (relatives of hummingbirds) – were the most adept in learning and remembering a large number of sounds. 

These species were also the only ones capable of mimicking other species, which, according to Audet, is the “epitome of vocal learning.”

Cognitive tests 

The scientists then ran several cognitive tests on 214 birds from 23 species, including two lab-raised bird species which were added to the wild birds. To test problem-solving abilities, they challenged the birds to remove a lid, pierce foil, and pull a stick to retrieve food. 

Moreover, they also assessed the birds’ self-control capacities by placing a transparent barrier between them and a snack, and checking how long it took the birds to stop trying to pass through the barrier and go around it. 

Finally, other tests were used to assess whether the birds can learn to associate a specific color with a food reward, and how quickly they adapted when the color changed.

Problem-solving abilities 

The experiments revealed a strong correlation between vocal learning and problem-solving abilities. Starlings, blue jays, and catbirds were both the most advanced vocal learners and the most adept at solving puzzles. 

The researchers also discovered that the better a bird was at finding its way around an obstacle, the more complex were its vocal learning skills. 

In addition, the investigations showed that advanced vocal learners and problem solvers had larger brains relative to the sizes of their bodies, which may be a biological basis for the study’s findings. However, no other associations were found between the rest of the cognitive tests and vocal learning ability.

“Our next step is to look at the brains of the most complex species and try to understand why they are better at problem solving and vocal learning,” Audet said. “We have a pretty good idea of where vocal learning happens in the brain, but it’s not yet clear where problem solving occurs.”

Study implications 

These findings suggest that vocal learning, problem solving, and brain size may have co-evolved, possibly as a way of increasing biological fitness. 

“Our findings help support a previously unproven notion: that the evolution of a complex behavior like spoken language, which depends on vocal learning, is associated with co-evolution of other complex behaviors,” concluded senior author Erich Jarvis, a biologist at Rockefeller.

The study is published in the journal Science.

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