Hummingbird bills are an evolutionary wonder

At first glance, hummingbird bills look like straws — long and thin, perfect for sipping nectar. But a new study reveals that this comparison is far from accurate.

These tiny birds have evolved intricate adaptations for drinking nectar, turning their bills into incredibly sophisticated tools.

In a recent study, a team led by Alejandro Rico-Guevara from the University of Washington discovered that hummingbird bills do much more than we thought.

The bills aren’t passive tools; they actively and flexibly engage with the bird’s tongue to help it drink nectar with lightning speed.

The team showed that, contrary to what you might expect, a hummingbird’s bill works in concert with its tongue, opening and closing in various sections while drinking.

This rapid coordination allows the bird to extract nectar quickly, helping it conserve energy while hovering mid-air.

Understanding hummingbirds — the basics

These little birds, found mostly in the Americas, are famous for their incredible ability to hover in place, thanks to their unique wing structure.

Their wings beat at mind-blowing speeds — up to 80 beats per second in some species — which creates the signature humming sound that gives them their name.

They also have extraordinary agility, flying not just forward but backward, sideways, and even upside down. What really sets hummingbirds apart is their insanely high metabolism.

To fuel their constant movement, they feed on nectar from flowers, using their long, specialized beaks and tongues to reach deep into blooms. They also eat insects and spiders for protein, keeping their diet balanced.

Hummingbirds are small — some, like the bee hummingbird, are just 2 inches long — but they pack a visual punch.

Their iridescent feathers shimmer in the sunlight, changing colors depending on the angle, making them one of nature’s most eye-catching creatures.

Plus, their energy and tenacity are unmatched, with some species migrating thousands of miles to escape the cold.

Complexities of drinking nectar

“Most hummingbirds drink while they’re hovering mid-flight,” said Rico-Guevara, who is also curator of ornithology at the UW’s Burke Museum of Natural History and Culture.

“Energetically, that is very expensive. Flying straight at commuting speeds uses up less energy than hovering to drink. So, hummingbirds are trying to minimize energy and drink as fast as they can — all from these hard-to-reach spaces — which requires special adaptations for speed and efficiency.”

Until now, scientists knew that hummingbirds use their long, intricate tongues to gather nectar. But how their bills contributed to this task remained a mystery.

Essential role of hummingbird bill

By filming hummingbirds in slow motion at field sites across Colombia, Ecuador, and the U.S., the researchers discovered the bill plays an essential role:

• The hummingbird opens just the tip of its bill to extend its tongue.
  
• After the tongue gathers nectar, the bill tip closes.
  
• To draw the nectar further, the midsection of the bill stays closed while the base opens slightly.
  
• The tip opens again for the next round, repeating 10-15 times each second.
  

Hummingbirds have highly specialized tongues — some even resembling intricate origami — to gather nectar. But this study highlights the often-overlooked importance of the bill.

Though it looks rigid, the bill is surprisingly flexible and essential for efficient nectar drinking.

Unique fluid collection of hummingbird bills

The University of Washington research also uncovered something unique about hummingbird feeding techniques.

“We already knew that hummingbird bills have some flexibility, for example bending their lower bill while catching insects. But now we know that the bill plays this very active and essential role in drawing up nectar that the tongue collects,” Rico-Guevara explained.

Most animals use just one method to collect fluids. Dogs and cats, for instance, lap water using what’s known as Couette flow, while mosquitoes use a suction-based system called Poiseuille flow.

Hummingbirds, however, use both approaches. Their bills and tongues work together, first lapping the nectar and then drawing it up through suction.

This dual method makes hummingbirds truly unique among nectar feeders.

“It makes sense that they would have to use both, given the pressure to reach the nectar deep within the flower and to feed quickly and efficiently,” said Rico-Guevara.

Evolution and future questions

The evolution of hummingbird bills is a fascinating example of adaptation. As flowers have evolved different shapes and sizes, hummingbird bills have also adapted, becoming perfectly suited for reaching deep into blossoms.

But with every answer, new questions arise. What muscles control these intricate movements? How does catching insects impact bill flexibility? There’s still much to learn about these tiny avian marvels.

The co-authors of the study include researchers from universities across the U.S. and the U.K., highlighting the international effort to understand these tiny birds.

In conclusion, hummingbirds, with their delicate beauty and incredible speed, are more than just nectar sippers.

Their bills, far from being mere straws, are the result of millions of years of evolution, fine-tuned to help these birds survive in a competitive environment.

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The study “Upper bill bending as an adaptation for nectar feeding in hummingbirds“ is published in the Journal of the Royal Society Interface.

Video Credit: Alejandro Rico-Guevara

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