A ‘copycat’ in animal kingdom: Chinese blackbirds mimic human-made sounds

Many songbirds can imitate various sounds from other birds, anuran species or even insects, during breeding season. This behavior is assumed to be a sort of courtship display. Many captive birds are reported to imitate human-made sounds, such as parrots, who can mimic human voices.

According to Changjian Fu, an ornithologist and PhD candidate at the Lab of Animal Behavior and Conservation of Nanjing University in China, human-made sounds imitated by wild birds are only reported as casual anecdotes, and no scientific study has attempted a systematic and quantitative analysis.

To that end, Fu and his colleagues described in a study published in the KeAi journal Avian Research how human-made sounds and those imitated by birds differ through quantitative investigations.

“We started by looking for a mimic living next to human communities. Under this scenario, urban birds provide us with an ideal object,” shares Fu. “We noticed that some Chinese Blackbirds (Turdus mandarinus) living in our campus can produce some sounds like alarms of electric mopeds incorporated in their songs sometimes. This is interesting because this kind of alarm is challenging sounds to produce.”

Consequently, the researchers decided to quantitatively investigate the electric moped sound mimicry in Chinese Blackbirds to understand the acoustic differences between the mimicry and sounds of real electric mopeds.

“We knew that male Chinese Blackbirds produce very large song repertoires, including various song types, mimicry, and their species-specific songs,” says Fu. “Nonetheless, It was a very challenging endeavor because Chinese Blackbirds can imitate a lot of sounds from other birds, and their species-specific songs are also various.”

During the study, which involves six months of field work and recording of over 40 electric moped sounds and 26 male Chinese Blackbirds’ song repertoires – including a total of 3,041 songs – the team discovered that the males (50%) could imitate the alarms of electric mopeds, and 84 songs contained the mimetic alarms (2.8%).

 “Mimicking human-made sounds in Chinese Blackbirds is more common than we think. However, we found obvious differences between these imitations and the real sounds,” adds Fu.

The team also discovered that, although the mimicry sounded vivid, quantitative analysis revealed obvious differences between the two sounds. Mimetic alarms possessed lower frequencies and fewer notes than the real alarms.

“As human-made sounds are difficult to produce, Chinese Blackbirds copy a simplified version of these sounds,” explains Fu. “We also found that the mimetic sounds from different sites also differed in acoustic structures. Chinese Blackbirds seem to imitate the sounds not only from electric mopeds directly, but also from other conspecific neighbors, which is known as ‘secondary mimicry.’”

Human-sound mimicry in songbirds may be universal, and its development is a complex process. The authors note that further studies should include how many human-made sounds are imitated, the mimicry accuracy, and the correlation between urbanization progress and the proportion of human-made sounds in mimetic repertoires of songbirds.

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Contact author name, affiliation, email address: Zhongqiu Li, Lab of Animal Behavior and Conservation, School of Life Sciences, Nanjing University, Nanjing, China, lizq@nju.edu.cn

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