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Bumblebees Can Fly Higher Than Mount Everest, Scientists Find

Photo of a bumblebee in flight in Oregon
A bumblebee takes flight in Deschutes National Forest in Oregon. Photograph by Michael Durham/Minden Pictures/Corbis

Talk about a high-altitude buzz. Bumblebees may be capable of scaling Earth’s tallest peaks, flying higher than Mount Everest, according to new research.

It’s difficult for most insects and birds to fly at extremely high altitudes where the air is thin and oxygen is scarce. Flapping wings push against the air to generate lift, and the thinner the air, the less force those wings can produce.

Yet bumblebees are abundant in high alpine regions. Researchers have long wondered how these tiny flyers were able to navigate the challenges of high-altitude flight—and just how high bumblebees could go. (See intimate portraits of bees.)

“We wondered if these challenges—the reduced air density and oxygen—would limit how high bees can fly,” said Michael Dillon, a scientist at the University of Wyoming in Laramie who recently spent time with colleagues capturing bumblebees at 10,660 feet (3,250 meters) above sea level in China.

“The answer seems to be a resounding no,” he said. “They’re capable of flying very, very high.”

Dillon and his team of researchers found that the bees they collected could fly at air pressure equivalents exceeding 24,275 feet (7,400 meters) above sea level, equivalent to some of the lower peaks in Nepal’s Annapurna mountain range. Two bumblebees were able to fly at more than 29,525 feet (9,000 meters)—higher than Mount Everest.

“We were shocked at how high they could fly,” Dillon said.

Into Thin Air

Dillon, an assistant professor of zoology and physiology, and his team collected bees from the mountains of China’s Sichuan Province (map), a region with one of the world’s highest diversity of bumblebee species. (See also “Bumblebees Taking a Nosedive in North America.”)

“As humans, we’re cold, we’re having trouble breathing, and we’re having to run around with nets to catch these bees that are zipping around as if it was nothing,” Dillon said, recounting the experience.

But capturing and testing the bees at high altitudes, he added, “was the only way that we could do these studies.” Once bees are captured and held for a while, they stop flying and simply wait to be released. So it was important to get them into a flight chamber immediately to conduct the experiments.

 

Photo of a been known as Bombus impetuosus hovering in front of flowers in China.
A bumblebee worker hovers in front of flowers at 10,500 feet (3,200 meters) in southwest China. Photograph by Michael E. Dillon

 

The researchers placed their bees in a plexiglass flight chamber in the field and used a hand pump to progressively pull air out of the chamber to generate the reduced air pressures the bees would face at high altitudes.

Dillon and colleagues kept thinning the air—which simulated increasing altitudes—until the bees were no longer able to fly.

The highest that researchers had previously found bumblebees was around 18,370 feet (5,600 meters) above sea level. As a result, on their first trip to the mountains, Dillon and colleagues underestimated the strength of the plexiglass they would need for the flight chambers.

As they reduced the pressure in the chambers, the plexiglass kept breaking before the bumblebees stopped flying, Dillon said. So they returned with newly built, thicker flight chambers.

Wider, Not Faster

The bumblebees adapted to the thin air at high altitudes not by beating their wings faster, but by swinging their wings through a wider arc, Dillon said. “They bring their wings closer up towards their nose, and farther back towards the tip of their abdomen,” he said.

Dillon thinks this helps the bumblebees displace more air, generating enough lift to keep them aloft at high altitudes.

The two highest fliers had the most muscle mass relative to their bodies, compared with the others, which may have allowed them to swing their wings wider. “You can think of them as these really bulked-up bees,” Dillon said.

He and collaborator Robert Dudley at the University of California, Berkeley, reported their results in a study published February 4 in the journal Biology Letters.

Despite their impressive flight capabilities, bumblebees have no reason to venture to the top of Mount Everest, since there are no flowers at such high altitudes. So why would they need such wing power ?

“They could use that excess flight capacity for some other really cool flight behaviors,” Dillon said, like transporting double their body weight in nectar and pollen. The extra flying ability could also come in handy when they need to escape predators, he added.

Next, Dillon plans to investigate another bumblebee behavior—how they’re able to breathe and deliver oxygen to their tissues at such high altitudes.

“They’re flying where there’s roughly a quarter of the oxygen at sea level,” he said. “So the oxygen supply is low and their metabolic rates are about a hundred times yours or mine.”

Comments

  1. Bradley Ball
    Culver City, CA
    February 12, 3:56 pm

    It seems to me that this article needs clarity.

    The experimenters apparently caught bees at one altitude:

    “capturing bumblebees at 10,660 feet (3,250 meters) above sea level”

    But then it is not clear where the decompression experiment took place:

    “Dillon and his team of researchers found that the bees they collected could fly at air pressure equivalents exceeding 24,275 feet (7,400 meters) above sea level, equivalent to some of the lower peaks in Nepal’s Annapurna mountain range. Two bumblebees were able to fly at more than 29,525 feet (9,000 meters)—higher than Mount Everest.”

    The experiment does not account for temperature change or energy requirements for a bee to fly to a higher altitude, not does it account for whether or not the bee is permanently damaged by insufficient oxygen or changes in partial pressures of gasses in the bee’s physiological fluid.

    The experimental conditions are not the same as what a bee would experience by flying to a higher altitude. There are probably great differences in physiological changes between flying from 10,000 feet to 20,000 feet compared to being decompressed at 10,000 feet by means of an air pump.

    The experiment only shows that the bee’s physiology is sufficient to move its wings in a flying manner at lower atmospheric pressure than is normal for its home range.

    The article is rather like reporting that a deep sea fish can swim near the surface by watching a fish flop around on a boat deck after being caught at depth.

    This was not a well-controlled experiment and is of little or no value. It seems to me that the researchers spent all their funding going on a mountain climbing vacation rather than have thought out the problem, acquired sufficient physiological monitoring technology, as well as knowledge of bee physiology, to have made a reasonable investigation.

    The bees were samples of convenience.

  2. Anderssen
    Europe
    February 12, 11:38 am

    HELLO I WANT TO KNOW MORE ABOUT BUMBLENE THANK YOU IN ADVANCE SINCERELLY ANDERSEN FAMILLY.

  3. John E. Oeste
    Ozona
    February 12, 6:32 am

    My poem would bring the NSA to my door. Bee sting therapy is proving to be a cornucopia of healing!

  4. Dan Swassing
    mount everest
    February 11, 12:35 pm

    God knows how high

  5. IMa ceitic
    Canada
    February 11, 8:26 am

    that rhyme’s weak.

  6. PimR
    RP
    February 11, 4:27 am

    liked your poem ;)

  7. Hendrik Voges
    South Africa
    February 11, 4:23 am

    If i remember correctly, this is the little critter that some other experts said should not be able to fly at all since they are not aerodynamic?
    Well done the bees. One up for you and nature.

  8. Ima Ryma
    February 5, 12:06 pm

    How high can a bumblebee fly?
    Nosy humans had to inquire.
    So with a net, they grabbed me. Why?
    To experiment, to my ire.
    They stuck me in some see through thing,
    Reduced the pressure of the the air,
    And so I wider arched each wing,
    Trying to fly me outta there.
    And so impressed, the humans got,
    Said that Mt. Everest could be
    Conquered by yours truly. Or not,
    If that test is left up to me.

    Mount Everest – the top, why go?
    No flowers grow there – doncha know!