Nav: Home

Slowed metabolism helps geese fly high

September 03, 2019

A few years before NASA astronaut Jessica Meir began learning to fly a spacecraft for her upcoming trip to the International Space Station, she was in flight-training of a different kind: teaching bar-headed geese how to fly in a wind tunnel at the University of British Columbia.

The goal was to understand how the birds -- who are famed for their long migrations between Mongolia, China and India -- frequently fly in severely low oxygen at extreme altitudes between 5000 to 6000m, or even as high as the summits surrounding Mt. Everest, which are at roughly 8500m. The findings of the research were published today in eLife.

"Flapping wings in flight is very metabolically costly and requires an enormous amount of oxygen -- and to do that where the air is so thin is remarkable," said Meir, who led the study as a postdoctoral fellow at UBC zoology. "We found that the geese maintained flight in extremely low oxygen levels in the wind tunnel by reducing their metabolism compared to when flying in normal oxygen levels."

While previous research suggested the geese have adaptations that allow them to maximize oxygen use at high altitudes, this study is the first to comprehensively measure their physiology during flight at simulated altitudes in a wind tunnel and gauge the associated metabolic costs.

But gathering the data required a little ingenuity, so Meir and her former UBC colleague Julia York each became mother goose to a gaggle of little bar-headed goslings born and bred at sea level.

As the first living things the birds saw when they hatched, the geese "imprinted" on Meir and York, allowing the pair to train the birds to fly in a wind tunnel wearing a face mask and a tiny backpack containing measuring equipment.

The researchers found that six of the seven birds that could fly in the tunnel were willing to fly in moderately low-oxygen levels around 5500m. Three of the birds also flew in severely low-oxygen conditions comparable to roughly 9000m, the maximum altitude at which bar-headed geese have been anecdotally reported to fly in the Himalayas.

"We found that during flight, the metabolic rate of these birds increased 16-fold from rest, along with an increase in the amount of oxygen transported per heartbeat and a smaller increase in heart rate," said principal investigator Bill Milsom, a professor emeritus at UBC zoology who has studied the geese for over a decade. "In comparison, humans and most animals can at best increase their metabolism ten-fold, so this is a remarkable capacity."

And when the going got tough, it appeared the birds actually became more efficient.

"We measured a drop in the metabolic cost of birds flying at the equivalent of 5500m in the wind tunnel, compared to flying at sea level oxygen conditions," said Meir. "When we decreased the oxygen further to the equivalent of roughly 9000m, the drop was even more extreme."

Data on heart rate, the rate of oxygen consumption and carbon dioxide production and blood temperature provided insights into the physiology underlying this unique ability.

"We were surprised to find that their heart rate during flight in reduced oxygen was no higher than during flights in normal oxygen levels," said co-author York, an undergraduate student at UBC at the time of the study and currently a PhD candidate at the University of Texas at Austin. "We also saw that the temperature in their veins decreased during our simulated flights, which is hypothesized to significantly increase the amount of oxygen they can carry in their blood."

Determining how these results relate to longer migratory flights of bar-headed geese at high altitudes will require further work to measure the physiological variables in the wild, or during longer flights in normal, low-oxygen and low-pressure conditions.

"Our findings are also relevant to all physiological and biomedical fields involving animals and humans in low-oxygen environments, from medical conditions such as heart attacks and strokes to procedures like organ transplants," said Meir.

For Meir, who has spent a good chunk of her career studying the physiology of animals in extreme environments, her trip to space on Sept. 25 is a turning of the tables, of sorts. Among the scientific experiments she will be supporting during her six-month mission, Meir will study how her own body responds to the extremes of space.

"It only seems fitting that it's now my turn to serve as the subject for many human physiology research experiments aboard the International Space Station," she said.

University of British Columbia

Related Heart Rate Articles:

Pupil dilation and heart rate, analyzed by AI, may help spot autism early
Autism and other neurodevelopmental disorders often aren't diagnosed until a child is a few years of age, when behavioral interventions and speech/occupational therapy become less effective.
Heart rate variation due to stress affects auditory attention
Study shows that brain activity related to auditory perception parallels heart rate, offering new perspectives for the treatment of attention and communication disorders.
In HIE, lower heart rate variability signals stressed newborns
In newborns with hypoxic-ischemic encephalopathy, lower heart rate variability correlates with autonomic manifestations of stress shortly after birth, underscoring the importance of this reading as a valuable biomarker, according to Children's research presented during the Pediatric Academic Societies 2019 Annual Meeting.
Your blood pressure and heart rate change to meet physical and social demands
Blood pressure and heart rate are not fixed, but rather they adapt to meet physical and social demands placed on the body, according to new research from Binghamton University, State University at New York.
Your genes determine how your heart rate responds to exercise
Your genes can determine how your heart rate and blood pressure respond to exercise -- and may act as an early warning of future problems with your heart or blood vessels -- according to new research published in The Journal of Physiology.
More Heart Rate News and Heart Rate Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...