The study focused on Chilean flamingos at the Nashville Zoo. (Credit: Victor Ortega Jiménez, UC Berkeley)
In a nutshell
- Flamingos aren’t passive feeders; they’re active predators that create underwater vortices using their beaks, necks, and feet to trap fast-moving prey like brine shrimp.
- Their unique L-shaped beaks and rapid “chattering” motions generate directional water flows, pulling food directly into their mouths like a built-in conveyor belt.
- These feeding tricks aren’t just bird brilliance; they could inspire new technology for filtering pollutants or particles from water by mimicking flamingos’ vortex-generating techniques.
BERKELEY, Calif. — Flamingos aren’t just standing around on one leg looking pretty in pink. These iconic birds are actually engineering geniuses, using their distinctive L-shaped beaks, flexible necks, and strange stomping behaviors to create underwater tornado-like vortices that trap 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,” says study author Victor Ortega Jiménez from the University of California, Berkeley, in a statement.
New research published in the Proceedings of the National Academy of Sciences reveals that flamingos create sophisticated fluid dynamics to capture fast-moving animals like brine shrimp in muddy, hypersaline waters that would challenge most other birds.
The researchers found that flamingos strategically use their feet, uniquely shaped beaks, and deliberate head movements to generate water flows and swirling eddies that effectively trap fast-swimming microscopic prey. This puts these lanky pink birds in the company of specialized predators that create traps.
“Think of spiders, which produce webs to trap insects. Flamingos are using vortices to trap animals,” says Ortega Jiménez.
How Flamingos Create Underwater Whirlwinds
If you ever see a flamingo stomping around in shallow water, know that it’s not just being quirky. It’s actually creating mini underwater tornadoes that stir up sediment and tiny animals, making them easier to capture.
Researchers from multiple universities trained Chilean flamingos at the Nashville Zoo to feed from water-filled aquariums. High-speed cameras and particle tracking technology let them visualize exactly what happens when flamingos engage in their strange feeding behaviors.
When a flamingo quickly pulls its head up from the bottom of a pond, it generates “tornado-like vortices” at speeds around 40 centimeters per second. These vortices stir up sediments and prey from the bottom. The unique L-shaped beak, which has long confused scientists trying to understand its purpose, turns out to be perfect for creating these vortical flows.
Flamingos also use “asymmetric beak chattering,” a rapid opening and closing of their jaws underwater at about 12 hertz (12 times per second, roughly the speed of a hummingbird‘s wingbeat), to create directional flows of about 7 centimeters per second. This flowing water carries prey items directly toward and into their beaks, like a conveyor belt delivering food right to their mouths.
The Science Behind the Beak
The team didn’t stop at just observing live flamingos. They created 3D-printed models of flamingo beaks and feet to test in controlled laboratory settings. The models confirmed that these body parts generate powerful vortices. They also found that the peculiar habit flamingos have of pointing their beaks downstream (opposite to how most filter-feeding animals orient) creates a “recirculation zone” behind the head where prey become trapped, similar to how leaves get caught in the swirling eddy behind a rock in a stream.
Victor Ortega Jiménez, UC Berkeley)
To test exactly how effective these techniques are, researchers designed a flamingo-inspired particle collection system combining a pump with mechanical chattering jaws. The system with chattering increased particle collection by approximately seven times compared to using only a pump. When they switched from collecting graphite particles to capturing live brine shrimp, the combined system caught about seven times more shrimp per second.
According to the research team, flamingos’ flexible feet create swirling water movements during stomping that lift particles and small organisms, concentrating them while simultaneously trapping fast-swimming creatures. The flexible webbing between flamingo toes passively expands when moving downward through water and collapses when moving upward, optimizing the vortex-creating action.
“Flamingos are super-specialized animals for filter feeding,” says Ortega Jiménez. “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.”
These birds feed in some of the most alkaline and salty waters on Earth, places where few other birds can survive, and now we know how they’ve adapted to thrive there.
Traditional descriptions of flamingo feeding have focused primarily on their upside-down posture and filter-feeding structures. However, this new understanding reveals flamingos as sophisticated predators using fluid physics principles to create multiple types of vortices that aid in trapping prey.
The researchers suggest the flamingo’s feeding mechanisms could inspire new engineering designs for particle collection systems that might help remove pollutants or harmful microorganisms from bodies of water.
There is more to flamingos than the eye can see. Evolution has shaped these birds into specialized predators, natural physicists that capture prey in environments few other birds can successfully hunt in.
Paper Summary
Methodology
The research team used multiple approaches to study flamingo feeding mechanics. They trained Chilean flamingos at the Nashville Zoo to feed from transparent aquariums while being filmed with high-speed cameras. Particle image velocimetry (PIV) allowed researchers to visualize and measure water flow patterns during feeding behaviors. They supplemented observations of live flamingos with laboratory experiments using 3D-printed models of flamingo beaks and feet. These physical models were tested in water with food particles and live brine shrimp. Finally, the team used 3D computational fluid dynamics (CFD) simulations to further analyze fluid flows around flamingo body parts. The combination of live animal observations, physical models, and computer simulations provided multiple lines of evidence for how flamingos manipulate water flow during feeding.
Results
The research identified several mechanisms flamingos use to generate fluid flows that aid in prey capture. When retracting their heads from water at speeds of about 40 cm/s, flamingos create tornado-like vortices that stir up bottom sediments and prey. Their rapid beak chattering (around 12 Hz) generates directional water flows of approximately 7 cm/s through asymmetric clapping of their mandibles. The unique L-shaped beak facilitates vortex formation during head retraction and creates a recirculation zone during interfacial skimming that helps trap prey. Additionally, flamingos’ webbed feet generate horizontal eddies during stomping that concentrate prey in front of their heads. Experiments with a flamingo-inspired particle collection system showed that beak chattering improved capture rates by approximately seven times compared to using just suction.
Limitations
While the study provides strong evidence for flamingos’ hydrodynamic feeding strategies, some limitations exist. Observations were limited to captive Chilean flamingos, and wild flamingo behaviors might differ in natural habitats. The research focused primarily on adult flamingos with fully developed L-shaped beaks, leaving questions about how juvenile flamingos with straighter beaks feed. The study also leaves open questions about potential cooperative feeding behaviors when multiple flamingos feed in groups, which could further enhance vortex generation. Additionally, while the researchers demonstrated that the mechanisms trap prey effectively, they didn’t quantify the energetic efficiency of these feeding strategies compared to other possible methods.
Funding/Disclosures
The research was funded by multiple sources, including NSF CAREER IOS-1941933, the Open Philanthropy Project, and internal funding from the University of Maine and the University of California, Berkeley. The work was approved by the Animal Care and Use Committee of the Georgia Institute of Technology with proper animal welfare assurance protocols. No competing interests were declared by the authors.
Publication Information
The paper titled “Flamingos use their L-shaped beak and morphing feet to induce vortical traps for prey capture” was published in the Proceedings of the National Academy of Sciences (PNAS) on May 12, 2025. The research was led by Victor M. Ortega-Jimenez from the Department of Integrative Biology at UC Berkeley, with co-authors from the University of Maine, Georgia Institute of Technology, Kennesaw State University, and the Nashville Zoo.
