Flamingos seem like some of the most elegant and serene creatures in the animal kingdom. But underneath their pink, shrimp-colored plumage lies a surprisingly aggressive predator and well-coordinated.
A new study published in Proceedings of the National Academy of Sciences reveals that flamingos are dynamical predators. Using a combination of webbed feet, L-shaped beaks, and fast head movements, they whip up underwater tornadoes to trap and devour agile prey like brine shrimp and copepods.
“Flamingos 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, a biologist at the University of California, Berkeley, and the study’s lead author.
Tornadoes, Chattering, and Skimming
This all started with a simple observation. On a visit to Zoo Atlanta with his family in 2019, Ortega Jimenez noticed ripples spreading from the submerged heads of Chilean flamingos. He thought it was a bit strange and wondered what was happening underneath the ripples.
Driven by curiosity, he assembled a team of engineers, zoologists, and fluid dynamicists. Working with live flamingos at the Nashville Zoo and using high-speed cameras, lasers, and even 3D-printed flamingo heads and feet, they began to decode the unseen ballet.
What they discovered is that flamingos precisely manipulate water. As they feed, they stomp their floppy, webbed feet in what looks like a dance, creating horizontal eddies in the muddy bottom. These eddies lift sediment and microscopic animals toward the surface while the birds quickly retract their heads upward through the water, generating tornado-like vortices around their beaks.
The result is a self-made, swirling water trap that funnels live prey straight into their mouths.
But that’s just the start of it.
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While their heads are upside down, the flamingos start a rapid snapping motion—called “chattering”—clapping their beaks about 12 times per second. This beak movement produces a narrow, unidirectional jet of water that draws prey into their mouths. Experiments using a mechanical beak attached to a small pump showed that this chattering increases brine shrimp capture by up to seven times.
“The chattering actually is increasing seven times the number of brine shrimp passing through the tube,” Ortega Jiménez said. “So it’s clear that the chattering is enhancing the number of individuals that are captured by the beak.”
In other words, flamingos are vacuuming up their dinner.
Form Follows Function
The flamingo beak, unique among birds, has a flattened and sharply bent L-shape. This design lets them feed upside down with the beak tip lying nearly parallel to the bottom.
During “skimming”—a different feeding behavior performed at the water’s surface—the bird’s curved beak slices through the flow, generating a series of symmetrical, sheet-like vortices known as a von Kármán vortex street. These eddies steer prey into a recirculating zone just behind the beak’s tip, where it is easily trapped and filtered.
3D printed beak models tested in a flow tank showed that this shape optimally places the beak within the vortex street’s collection zone. The researchers confirmed this by introducing live brine shrimp, which became trapped in the flow—unable to escape the swirling current.
The team also created mechanical models of both rigid and flexible flamingo feet. Only the flexible, floppy ones—like the real thing—produced coherent vortices strong enough to trap fast-moving prey. The motion even proved effective against larger aquatic bugs like water boatmen, which can swim at nearly 15 centimeters per second.
Sunghwan Jung, a biophysicist at Cornell University not involved in the study, called it “an outstanding demonstration of how biological form and motion can control the surrounding fluid to serve a functional role,” per the NYT.
Vortex Hunters
For decades, biologists assumed flamingos were passive filter feeders—akin to baleen whales or mussels. The new research flips that assumption.
“It seems like they are filtering just passive particles, but no, these animals are actually taking animals that are moving,” Ortega Jiménez said.
This predator strategy may be more common than previously thought. Other animals—like phalaropes, jellyfish, starfish, and even paddlefish—create similar vortices to corral food. One study even found that Wilson’s phalaropes can double their feeding rate by tagging along behind stomping flamingos.
Future research will explore how the flamingo’s piston-like tongue and the fine, comb-like structures inside its beak contribute to this remarkable feeding machine.
“Flamingos are super-specialized animals for filter feeding,” Ortega Jiménez said. “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.”