This bird’s song sounds exactly like dripping water. Scientists just worked out how it does it 

Cowbirds are famous for their remarkable song, a bubbling, liquid sound often compared to water droplets splashing into a pond. Now, scientists have uncovered how these birds pull off this acoustic trick – and it’s far more complex than previously thought.

Published in the journal Current Biology, the research shows that the cowbird’s song is produced through a finely tuned mix of specialised vocal anatomy, precise breath control and rapid switching between sound sources.

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How cowbirds make their water-like song

Like all birds, cowbirds produce sound using the syrinx – a vocal organ with two independent sound sources, one on each side. But in cowbirds, these sides are not the same.

“What's striking about the cowbird syrinx is that the left pair of vocal folds is much bigger than the right pair,” says Franz Goller, a biologist at the University of Utah who led the study.

The researchers believe that higher sound frequencies are produced on the smaller right side of the syrinx, while the larger left side contributes lower sounds. By rapidly switching between the two sides, cowbirds create the bubbling quality that gives their song its water-like sound. 

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But anatomy is only part of the story. Focusing on the brown-headed cowbird (Molothrus ater) – one of six cowbird species and a familiar bird across much of North America – the team also discovered that the birds use an unusual breathing technique to help shape their song. 

According to co-author Brenton Cooper, a neuroscientist who studies speech and language, cowbirds briefly hold their breath to build up pressure in the syrinx. When that pressure is suddenly released, it produces a sharp burst of sound – much like a splash.

Top image: brown-headed cowbird (Molothrus ater). Credit: Getty

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