05-14-2025

You’ll never guess what flamingos are doing with their feet in the water

Earth.com staff writer

At first glance, a flamingo feeding in shallow, alkaline water seems calm and graceful. Its long neck arcs gently, and its head remains submerged, giving the impression of a bird quietly filtering water.

But beneath the surface, there’s a flurry of activity. Flamingos are far from passive feeders. They are busy stirring up the water, creating tiny underwater tornados to trap their prey.

This behavior, observed in Chilean flamingos at the Nashville Zoo, has been the subject of extensive research by scientists from the University of California, Berkeley, in collaboration with teams from Georgia Institute of Technology, and Kennesaw State University.

By combining footage of real birds with experiments using 3D-printed models of flamingo beaks and feet, the researchers discovered how these birds rely on a mix of footwork, head movement, and rapid beak clapping to catch live 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, an assistant professor of integrative biology at UC Berkeley who specializes in biomechanics.

“Think of spiders, which produce webs to trap insects. Flamingos are using vortices to trap animals, like brine shrimp.”

When flamingos dance, they’re hunting

The team found that flamingos use their webbed, flexible feet to stir up sediment from the lakebed. As they “dance” in place or move in circles, they lift and press their feet gently into the mud. These movements send spirals of water and sediment swirling outward.

At the same time, the bird plunges its head straight up and down, beak first, into the water. This creates a spinning vortex that sucks the loosened particles – including prey – upward.

The flamingo’s head remains upside down while its specialized beak goes to work, clapping rapidly to generate even more motion.

“It seems like they are filtering just passive particles, but no, these animals are actually taking animals that are moving,” Ortega Jiménez explained.

How the beak gets the job done

The shape of a flamingo’s beak is unlike any other bird. Flattened at the front and bent like an L, it’s designed to function upside down.

When the bird pushes its head forward, it performs a motion called skimming. During this, the bird claps its beak quickly, generating sheet-like currents known as von Kármán vortices. These swirling currents help trap fast-moving prey like brine shrimp.

The study also examined how this chattering action influences the feeding process. Using a 3D-printed beak attached to an actuator and a small pump to mimic the flamingo’s tongue, the researchers were able to measure the effects.

“The chattering actually is increasing seven times the number of brine shrimp passing through the tube,” said Ortega Jiménez. “So it’s clear that the chattering is enhancing the number of individuals that are captured by the beak.”

Mechanics of flamingo feeding

Ortega Jiménez’s curiosity about flamingos began during a family visit to Zoo Atlanta just before the COVID-19 pandemic. He noticed that although the birds seemed to be feeding peacefully, something more complex had to be happening beneath the surface.

“We don’t know anything about what is happening inside. That was my question,” he said.

Back then, Ortega Jiménez was a postdoctoral fellow at Kennesaw State University. From there, his research path led him to Georgia Tech and later to UC Berkeley, with time at the University of Maine in between.

Flamingos feed by dragging their flattened beaks forward along the bottom of shallow lakes. To increase the efficiency of feeding, they stomp dance to churn the bottom, create an upwelling vortex with their heads and clap their beaks constantly to draw food, like brine shrimp, into their mouths. Credit: Aztli Ortega — Flamingos feed by dragging their flattened beaks forward along the bottom of shallow lakes. To increase the efficiency of feeding, they stomp dance to churn the bottom, create an upwelling vortex with their heads and clap their beaks constantly to draw food, like brine shrimp, into their mouths. Click image to enlarge. Credit: Aztli Ortega

At each stage, he collaborated with engineers and used technology like lasers and high-speed imaging to get a clearer view of the hidden mechanics behind flamingo feeding.

The power of flamingo feet

Flamingo feet are as important as their beaks. Their webbed feet are soft and floppy, which helps them avoid suction when lifting their feet from muddy bottoms.

Ortega Jiménez created rigid and flexible models of the feet to test their effects in water. He discovered that the floppy design is much better at generating forward-moving vortices, while rigid ones mostly just create turbulence.

In shallow water, you might catch a glimpse of a flamingo’s dance. It’s not just for show. Each motion helps concentrate prey in just the right spot for the flamingo to feed.

Feeding in full motion

The team also built a 3D model of the L-shaped beak to test how upward head motions create vertical vortices. These movements trap particles and small creatures like copepods and brine shrimp.

The head moves at about 40 centimeters per second – fast enough to capture even quick-swimming prey.

The chattering motion involves the lower beak moving about 12 times per second, while the upper beak stays still.

“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.”

Still more to learn from flamingos

The next step for Ortega Jiménez is to study how the flamingo’s tongue and the beak’s comb-like edges help it filter out food from salty, sometimes toxic water. These features could inspire future designs for environmental tools.

“Flamingos are super-specialized animals for filter feeding,” he 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.”

From lakebeds to lab models, the flamingo’s feeding technique is more than a quirky behavior – it’s a glimpse into nature’s quiet engineering. As the research continues, these elegant birds may help shape future tools for water cleaning and soft-footed robotics.

Click here to watch a video of flamingoes making water tornadoes…