Make some noise for the white bellbirds of the Brazilian Amazon, now the bird species with the
loudest known mating call.
The birds (Procnias albus) reach about 125 decibels on average at the loudest point in one of their songs, researchers report October 21 in Current Biology. Calls of the previous record-holder — another Amazonian bird called the screaming piha (Lipaugus vociferans) — maxed out around 116 decibels on average. This difference means that bellbirds can generate a soundwave with triple the pressure of that made by pihas, says Jeff Podos, a behavioral ecologist at the University of Massachusetts Amherst, who did the research along with ornithologist Mario Cohn-Haft, of the National Institute of Amazon Research in Manaus, Brazil.
The team measured sound intensity from
three pihas and eight bellbirds. Each sounded off at different distances from
the scientists. So to make an accurate comparison, the researchers used
rangefinder binoculars, with lasers to measure distance, to determine how far
away each bird was. Then, they calculated how loud the sound would be a meter from
each bird to crown a winner.
The small white bellbird, which weighs less than 250
grams, appears to be built for creating loud sounds, with thick abdominal muscles
and a beak that opens extra wide. “Having this really wide beak helps their
anatomy be like a musical instrument,” Podos says.
Being the loudest may come with a cost: White
bellbirds can’t hold a note for long because they run out of air in their
lungs. Their loudest call sounds like two staccato beats of an air horn while
the calls of screaming pihas gradually build to the highest point.
Bellbirds don’t use their loudest call to communicate across long distances like other animals do, Podos says. Instead, a male white bellbird blasts its loudest song in the face of a nearby female.