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06-16-2024

Tiny bird sheds light on the evolution of vocal learning

In the world of birdsong, some species stand out for their vocal learning ability to learn new sounds, such as parrots, songbirds, and hummingbirds.

Recently, researchers have uncovered that New Zealand’s smallest bird, the titipounamu, may also possess a rudimentary version of this talent.

Rethinking vocal learning in birds

Research from the University of Auckland is challenging traditional views on how and when vocal learning evolved in birds.

Until now, scientists believed that birds were divided into two groups: those that can learn sounds and those that cannot. However, the new study provides evidence that complicates this binary classification.

Surprising vocal similarities

The study revealed that titipounamu living near each other had remarkably similar vocal signatures, despite being distantly related.

Conversely, close relatives living far apart sounded different. This suggests that their sounds may not be entirely innate but learned from their surroundings.

Tiny bird, big implications

Weighing as little as five or six paper clips, the titipounamu inhabits high-altitude mature native forests, feeds on insects, and produces high-pitched sounds that are often inaudible to humans.

This bird, one of New Zealand’s two surviving native wren species, serves as an evolutionary link between songbirds and parrots, two of the most impressive learners.

“If New Zealand wrens are vocal learners, then it is likely that the common ancestor of parrots and songbirds was also capable of rudimentary learning,” noted Dr. Kristal Cain. “This ability in birds could have evolved millions of years earlier than we previously thought.”

Vocal learning in the Titipounamu

To investigate vocal learning, scientists monitored titipounamu nests at Boundary Stream Mainland Island in Hawke’s Bay. They banded individual birds and recorded over 6,800 feeding calls made by adult birds bringing food to their young over three summers.

Detailed analysis of these recordings, using spectrograms or “voiceprints,” revealed unique individual vocal signatures.

The researchers also gathered genetic information on the population and employed advanced genetic methods to determine the influence of genetics versus social environment on vocal signatures.

Their findings suggested that the social environment played a significant role, showing similarities to known vocal learners like the zebra finch.

A spectrum of learning

The study’s findings indicate that the classification of birds as either vocal learners or non-learners might be too simplistic.

“A growing body of evidence suggests we may need to stop classifying birds as either vocal learners or vocal non-learners,” said Cain. “The ability may be much more widespread and likely exists along a spectrum.”

Connections to other species

Most animals communicate with unlearned, innate vocalizations. However, vocal learners include humans, whales, dolphins, elephants, and bats.

“The vocal behavior that we were unravelling in this study is very similar to what is known as vocal accommodation in human linguistics,” said Dr. Ines G. Moran.

“It’s similar to our ability to adjust our ways of speaking in different social, dialectic, or hierarchical settings – modulating our voices to better fit in certain social groups.”

New insights into vocal learning

This study on the tiny titipounamu opens new doors to understanding the evolution of vocal learning.

The research suggests that vocal learning might be more widespread among birds than previously thought, offering insights into the origins of complex communication in the animal kingdom.

“Vocal convergence and any predispositions for vocal production learning are behaviors that are easily overlooked without extensive analyses, so sophisticated and in-depth future studies are needed to explore their possible existence and their origins in other animal groups,” wrote the study authors.

More about the titipounamu 

The titipounamu, also known as the rifleman, measures only about 8 centimeters in length. The bird’s name, rifleman, comes from its olive-green plumage, which resembles the uniforms worn by British riflemen. 

The titipounamu is known for its distinctive, high-pitched call and its ability to cling to tree trunks and branches, similar to a woodpecker. It primarily feeds on insects and spiders, using its thin, pointed bill to probe into crevices and bark. 

The bird’s habitat includes native forests and shrublands, where it nests in tree cavities or holes in the ground. Conservation efforts are ongoing to protect the titipounamu, as habitat loss and introduced predators pose significant threats to its population.

The study is published in the journal Communications Biology.

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