Some Songbirds Use Blinks to Defend Their Territory

White-throated dippers are brown-feathered, plump little songbirds; they often stay alongside riverbanks and defend their territory by chirping at any birds that drop by. But the loud rivers burbling close to them can at instances drown out their songs. In a current Current Biology examine, scientists discovered that the undeterred birds change up their communication technique when the streams get too loud for interlopers to listen to their territorial songs, and use their distinctive eyelids as an alternative.

“Their white eyelids are so striking—every time they blink, it’s like a tiny flash,” says Henrik Brumm, senior examine writer and a behavioral ecologist on the Max Planck Institute for Biological Intelligence, Germany. The snow-white eyelids are so conspicuous as a result of the birds’ plumage is a wealthy darkish brown. “That made us wonder: Could this be a way of communicating in the noisy habitats where they live, along fast-flowing rivers?”

The researchers discovered that the birds blinked at a better frequency because the river received noisier, and the birds that blinked extra additionally didn’t sing as loudly—particularly when one other member of their species was round. Based on these findings, the scientists recommend that the birds could favor to utterly shift their communication technique—from listening to trying and singing to blinking—when the waters develop into too loud. “Natural noise, like rushing water, can be a powerful force shaping how animals communicate,” says Brumm.

“Every time they blink, it’s like a tiny flash.”

Brum and his colleagues noticed the birds in Yorkshire Dales National Park in northwest England. They used a telescope or binoculars to rely the dippers’ blinks and to identify some other birds of the identical species round them. They additionally recorded how loudly they sang utilizing a directional microphone, a selected form of microphone that helps choose up sounds from a selected path in noisy environments, and recorded river noise individually utilizing a sound degree meter. To simulate the presence of an intruder, they positioned a loudspeaker close to the dippers’ nests on the riverbank and performed songs of dippers singing.

The hardest a part of the experiment, Brumm says, was the climate. “Dippers sing in February, so we spent more than 300 hours in the freezing, wet north of England,” Brumm says. “I still don’t know how the team managed to get their clothes dry each evening!”

“Stay Away” Signaling

Brumm and his staff initially seen that the birds gave the impression to be utilizing their blinks to ship a “stay away” sign to intruders. The extra aggressively the birds reacted to simulated intruders, the extra they blinked. Then when the researchers analyzed their area knowledge, they found that because the river noises grew, so did the speed at which the birds blinked, so long as one other same-species chook was round to obtain their alerts.

“When other dippers are around, the birds sing softer and blink more, which shows a clear shift between sound and visual signals,” explains Brumm.  “The surprising part is that switching between senses like this—from hearing to seeing—is very rare in animal communication.” Another instance of such switching may be present in white-crowned song sparrows, which select to flutter their wings as an alternative of singing softly in noisy city settings.

Clinton Francis, an ecologist on the California Polytechnic State University notes that white-throated dippers stay in a extremely specialised surroundings that few different chook species occupy. “They’re in these areas that have this rushing whitewater—really, really difficult visual fields and also super loud,” he says.

Francis, who wasn’t concerned with the dipper examine, thinks many different organisms may very well be dynamically adjusting how they convey based mostly on the world round them, however scientists haven’t but managed to decode their alerts. “Maybe we aren’t paying enough attention to some of these visual signals that animals are using with one another all the time,” he says. “Different gestures could be important visual signals, [but] we have not interpreted them as such yet.”

Brumm agrees. “Animal communication is far more complex and flexible than most of us imagine,” he says. “Even a simple blink can carry meaning—especially when nature forces animals to get creative.”

Lead picture by Kevin Duclos

• Rohini Subrahmanyam

  Posted on September 25, 2025

  Rohini Subrahmanyam is a biologist turned science journalist. She loves writing about fascinating creatures on our planet. Subrahmanyam obtained a Ph.D. from the National Center for Biological Sciences on the Tata Institute of Fundamental Research in India. Follow her on X (previously Twitter) @rohsubb and on LinkedIn, and see her portfolio here.