AMHERST, Mass. — University of Massachusetts Amherst's Jeff Podos and his former UMass Amherst graduate student João C.T. Menezes have just found two contenders for the world's loudest bird, the bare-throated bellbird and the red-legged seriema, on their way to partially solving the mystery of why some birds are so much louder than others.
This isn't the first time that Podos has made such a discovery. In 2019, he discovered that the Amazon's white bellbird had the world's loudest bird call —louder than standing next to a revving chainsaw—a claim later confirmed by Guinness World Records .
But setting world records is only the byproduct of Podos and Menezes's research.
The new study, published recently in Evolution , is the latest in the authors' career-long quest to understand the role evolutionary biology plays in how birds communicate with each other. But searching for record-breaking birds wasn't what Menezes and Podos were after. Instead, they wanted to know if there are physical characteristics of a bird's body that can predict how loud its call will be, and how, or if, loudness is related to a bird's ecological niche and specific social organization.
"Figuring out how loud a bird call is should be pretty easy in the lab," says Menezes, who completed this research as part of graduate work at UMass Amherst. "But until very recently, it has been very challenging to do in the field, and there's very little data to draw on."
This is because volume, or amplitude, is dependent on distance. A scream that is ear-splitting up close might barely register at a few hundred meters.
One method to gauge the amplitude of a bird call is to capture the bird you're interested in, bring it back to the lab and run controlled experiments there—which is just not practical, especially when working internationally and comparing large numbers of birds.
"You have to get your boots on the ground," says Podos, who accompanied Menezes in measuring the amplitudes of 123 birds in the areas around Amherst, Massachusetts and across Brazil.
But you also have to have the right tools in hand, and, until recently, they didn't exist. It wasn't practical for ornithologists to reliably measure amplitude and distance at the same time. That is, until golfers invented accurate laser rangefinders and those monitoring workplace safety built high resolution, portable sound meters.
Menezes and Podos have been early adopters of these new tools, and, once properly equipped, were able to gather reliable amplitude data on 123 species, 113 of which had never before had their volume catalogued. "We've been able to vastly increase the number of species for which there is amplitude data," says Podos. "This is basic, foundational research that no one else has managed to do on this scale, and it points to all sorts of other questions that would be fun to follow up."
What they discovered is, first, that there is an enormous, 58-decibel variability in the volume of bird calls, from the hummingbird (64 decibels, about the volume of a normal conversation), to bare-throated bellbirds and red-legged seriema, both of which rose above 120 peak decibels—louder than standing chainsaws and jackhammers.
They also discovered that, as expected, the loudest birds are typically bigger, with bulky muscles that may allow greater air compression for explosive volume, and have wider beak openings—think of how musical instruments with wide bells that can help amplify their volume, like trumpets.
However, the data did not support any clear, broad predictions about why amplitude might serve an ecological and evolutionary purpose. Menezes and Podos had hypothesized that the loudest birds would be weaker flyers (volume would make up for limited mobility), live in dense forests (which would limit birds' abilities to see each other) and practice polygamy (the farther a mating call travels, the more mates it would presumably attract).
"We now know some of the hows," say Menezes. "Bigger bodies and wider beaks, but we've yet to discover the whys, and we probably need much more data from many more species to be able to tease out what's going on the ecological and evolutionary front."
That's just fine with Podos, who is excited to get back out in the field with Menezes, his golf rangefinder and sound meter. "Yogi Berra said 'you can observe a lot by watching,' and the world has some beautiful things to see," says Podos. "You can't do this kind of work in the lab, or by scraping data from the internet. You have to get out into the world, you have to pay careful attention to what you're seeing and hearing, and anything you do in the field that forces you to observe more carefully is really fun—it takes you back to the roots of why we do science in the first place."
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