Flamingo physics shocks science world as birds form fish-catching tornadoes

Yahoo

15-05-2025

Though flamingos often appear to feed serenely in shallow lakes, their hunting behavior is anything but passive. A new study reveals that these birds create swirling underwater vortexes to trap and consume live prey like brine shrimp, disproving their reputation as simple filter feeders.
A research team at the University of California, Berkeley uncovered how flamingos use a coordinated sequence of footwork, head motion, and beak mechanics to engineer tiny underwater whirlpools that draw in their prey.
'Flamingos are actually predators, they are actively looking for animals that are moving in the water, and the problem they face is how to concentrate these animals, to pull them together and feed,' said Victor Ortega Jiménez.
'Think of spiders, which produce webs to trap insects. Flamingos are using vortices to trap animals, like brine shrimp.'
In collaboration with Georgia Tech, Kennesaw State University, and the Nashville Zoo, the team studied Chilean flamingos both in captivity and through lab simulations. Using laser imaging and 3D-printed models of flamingo feet and beaks, they discovered that the birds stir up sediment with their webbed, floppy feet, generating spinning flows.
Then, by pulling their heads upward through the water, the birds lift these whorls to the surface.
While submerged upside down, the birds rapidly chatter their angled beaks—flattened and L-shaped—to create even finer vortexes that guide prey toward their mouths. Their beaks work like a pump, using these flows to suck in moving organisms and filter out unwanted particles.
'It seems like they are filtering just passive particles, but no, these animals are actually taking animals that are moving,' Jiménez said.
At UC Berkeley, the researchers fitted a real flamingo beak to an actuator and used a small pump to simulate tongue action.
'The chattering actually is increasing seven times the number of brine shrimp passing through the tube,' he said. 'So it's clear that the chattering is enhancing the number of individuals that are captured by the beak.'
https://www.youtube.com/watch?v=MDzIufdF3KA&t=2s
'We observed when we put a 3D printed model in a flume to mimic what we call skimming, they are producing symmetrical vortices on the sides of the beak that recirculate the particles in the water so they actually get into the beak,' Ortega Jiménez said. 'It's this trick of fluid dynamics.'
This unique feeding strategy has potential applications beyond biology. The principles could help design better systems for filtering microplastics, self-cleaning filters based on vortex chattering, or locomotion techniques for robots in watery or muddy environments.
'Flamingos are super-specialized animals for filter feeding. It's not just the head, but the neck, their legs, their feet and all the behaviors they use just to effectively capture these tiny and agile organisms," Jiménez concluded.
The findings have been published in Proceedings of the National Academy of Sciences.