Scientist Explains How to Study the Metabolism of Ultra High Flying Geese

Geese get a bad rap for being ornery

and attacking children and what not,

but the bar headed goose is actually a pretty laid back

species that makes an incredible journey over the Himalayas,

going up in altitudes of 26,000 feet.

To learn more about what is physiologically happening

in the bodies of these geese, researchers strapped

backpacks on them and gave them face masks and put them

in a wind tunnel.

To learn more, we sat down with a scientist

who worked on the study.

Hi, I'm Julia York.

I'm currently a PhD candidate at the

University of Texas at Austin.

And can you walk us through how you raise these geese

from birth and how you prepare them for this experiment?

We wanted to train these geese to fly in a wind tunnel

so that we could manipulate them experimentally

and measure their metabolic rate

in a controlled environment.

And we wanted the geese to be as calm and comfortable

as possible under these conditions.

So we raised the geese from eggs and spent every day

with them for a whole summer, going for walks,

and taking naps, and going for swims, and eating lettuce.

And so they thought we were their mom and that they

were comfortable around us and we could get them trained

on the experimental equipment.

And what goes through that experimental setup here?

How was the wind tunnel arranged?

How were the geese kept comfortable?

All that sort of stuff.

It's actually a wind tunnel that is designed for cars,

but it was large enough that we could fly a goose in it.

We set it up with tubes that attach to a mask that we built

to fit the geese, a little plastic mask, and measure the

oxygen that they were consuming and the CO2 that they

were producing, and then introduce nitrogen into the air

that they were breathing to reduce the relative amount

of oxygen in each breath and simulate altitude.

And I also understand that they're wearing backpacks?

So they have these little backpacks on that strap

around their wings and those held the heart rate monitors,

primarily, but also we did a subset of experiments

where we tested the amount of oxygen and the temperature

of their blood.

And while we were doing those experiments, the backpacks

also held those monitors.

Can you walk us through some potential challenges here?

I imagine there were a few of them training geese

to fly calmly in a wind tunnel with a mask

and a backpack on.

Geese are not food motivated animals, like dogs.

You can't give 'em a treat to reward them

for their behavior.

They kind of do what they wanna do. [chuckles]

So when we first brought them into the wind tunnel,

obviously, we started them off very slowly,

just getting them used to the environment,

comfortable in that setting.

And then we started turning on the wind tunnel

so they could feel the air moving and the noise.

Then we started allowing them to fly with the air running,

without the equipment.

Sort of like a treadmill, but for flying.

Some of the geese just did not get it, [laughs]

and would fly maybe for a minute, but then land

and sort of sit there and wait for it to be over.

So out of 19 total geese that we tried to train,

we only got seven to fly consistently in the wind tunnel.

And those geese would fly one good, long flight per day.

And what were you finding as these geese were flapping

around in the wind tunnel?

The three major things we found were that they were able

to minimize their metabolic rate in low-oxygen conditions.

So either they were able to fly more efficiently

or reduce unnecessary metabolic processes.

We can't really differentiate between those two hypotheses.

The second thing we found was that their heart rate

didn't change between high and low oxygen conditions.

That tells us that increase in heart rate in the wild

is due to some other component of altitude,

rather than the low oxygen.

And the third thing we found was that they were able

to drop their blood temperature as it goes towards

the lung during the flight.

Hypothesize to increase the amount of oxygen

that they're able to deliver to the muscle.

Physiologically, what is different about these geese

that allows them to survive at such high altitudes?

I mean, not only do they survive, right,

they do this amazing migration where they go from sea level

in India, all the way up to the passes in the Himalayas

without stopping in eight to 12 hours.

They breathe more deeply, which is

a more effective way to breathe.

And then they have larger lungs for their body size

so they can increase the oxygen extraction

from every breath.

They are able to increase their stroke volume,

which is the amount of blood pumped per heart beat.

And they have hemoglobin in their blood that binds oxygen

more tightly than other birds.

So there's just a large suite of adaptations that make

these birds able to do this migration.

Bringing us around to humans, because we're selfish.

How about these findings tell us about how humans experience

altitude sickness and potentially how we might be able

to treat that by learning more about how geese deal

with these things?

In mammals, we will increase our breathing,

our rate of breathing, and response to low oxygen,

which reduces the amount of CO2 in our blood.

In the geese, they have a lot of adaptations across

all the way from the way they breathe down to the

mitochondria at the muscle that optimized the way

they use oxygen.

For example, their blood vessels in their brain are not

sensitive to CO2, so they don't get cerebral edema

in the same way that we do.

They don't get altitude sickness because of that.

We understand what our responses are to these situations

and by studying animals that are adapted to these

low oxygen conditions, what can we learn from that

and bring that into medicine or high altitude

or any of the things that humans struggle to do

in these conditions.

Thank you for joining us.

Thank you so much for your interest in the geese.