Like humans using body language to send non-verbal signals, some bird species communicate without opening their beaks.
The fork-tailed flycatcher is among the birds that rustles its feathers or flaps its wings to send messages during life’s biggest moments, whether it is fighting and mating.
Beyond being a quirky communication tool for the birds, this technique is also useful for researchers who want to learn more about these species.
In fact, detecting subtle differences in the sound from a rustling fork-tailed flycatcher has revealed two subspecies of the bird have different ‘accents.’
The findings were published in the journal Integrative and Comparative Biology.
The fork-tailed flycatcher lives in the American tropics. As its name suggests, the bird’s tail-feathers split into two long, elegant wisps. The side and shape of those wisps, it turns out, affects the sound the birds’ feathers make.
Researchers recorded these sounds and charted the differences and similarities between different birds. By listening to the fluttering sounds, called sonations, researchers discovered that the two subspecies of fork-tailed flycatcher, Tyrannus savana, sound a little different.
The subspecies were previously discovered, distinguished by their different migration patterns. The subspecies are:
Tyrannus savana savana,a migratory subspecies
Tyrannus savana monachus, which lives year-round in the northern part of South America
Take a listen — here is T.s.monachus, the migratory subspecies:
And here is T.s.savana:
The migratory subspecies of fork-tailed flycatcher breeds in the southern part of South America, but flies north in the winter, when the two subspecies live together. But in the migratory subspecies, males’ wing feathers are shaped differently to their residential counterparts: The tips of the feathers are skinnier.
Because of that, when these two subspecies flutter their feathers, the noise they make is ever so slightly different, too.
Valentina Gómez-Bahamón, a researcher at the Field Museum in Chicago, led the study. Gómez-Bahamón explains that the new findings help to confirm the differences between the two subspecies of fork-tailed flycatcher.
“We already knew from past genetic analysis that the two groups are becoming different species, so we wanted to know if there were any differences in the sounds that the males produce with their wings,” Gómez-Bahamón said in a statement.
“We not only confirmed the way that these birds make sounds with their feathers, but that the sounds are different for the two subspecies.”