Pitch (Not So) Perfect: Inbreeding Could Cause Birds to Sing Off-Key

A new study finds that inbred birds seem to be less musically talented than outbred ones, possibly hurting their chances of mating.

When it comes to musical talent, not all birds are created equal. But the specifics on why and how are still debated by researchers. Now we might know a little bit more. A new study shows how the singing of inbred male birds seems to be out of tune when compared with non-inbred birds, something that could hurt their chances of mating.

For the experiment, scientists paired brother and sister Atlantic Canaries (talk about getting unlucky) to produce new inbred offspring. Then, they assigned 19 inbred birds and 19 outbred birds to the same singing tutor. All the birds selected for the test were male, which, among Atlantic Canaries, are the ones competing for sexual attention.

After training, scientists recorded every bird for at least 3 hours, hoping to extract a minimum 240 seconds of audio. From these samples, they examined different values, such as the number and variety of syllables, length of the song, volume, and tone. For accuracy, they used computer software and logarithmic techniques to analyze the clips.

Going into the experiment, the researchers suspected inbreeding could play a role in the quality of canaries’ singing, specifically in their ability to learn how to sing and the complexity of the tunes. But when the results came in, they were surprised to find these traits were fine. Instead, the problem was elsewhere, says Raissa de Boer, doctoral student of the Department Biology at the University of Antwerp and lead author of the paper published in Proceedings of the Royal Society B last week. “What we found, shockingly, was an error in their pitch," de Boer says. "The inbred birds were singing out of tune."  

Next up, De Boer and her team wanted to know exactly how this lack of musical talent could affect breeding. They found that the females paired with inbred males laid smaller and fewer eggs than females paired with outbred birds. This, the scientists say, could be a sample of how instincts kick in to make natural selection possible. “It could be that females can discriminate between inbred and outbred males, perhaps as a result of the differences in their singing,” De Boer says.

This is not the first time research suggests inbreeding can have a negative effect on singing quality and reproductive success. Still, some scientists take these results with skepticism. Donald Kroodsma, a retired ornithologist specialized in avian communication and a close collaborator of The Cornell Lab of Ornithology, tells Audubon that evidence in this field is far from conclusive. “I’ve reviewed widely this topic, and I think that a lot of the research available out there is not accurate,” Kroodsma says. “We need to be cautious.”

De Boer agrees with Kroodsma’s call for further research. In the future, she wants to test if inbreeding can affect additional features of song when inbred birds have experienced disadvantageous environmental conditions during early development.

Despite the controversy, scientists hope that experiments like this help them untangle the mysteries of bird communication. “What are birds trying to say and why, that’s what we want to understand better," De Boer says. "Even if some of them are not very good singers.”