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Their wings can beat 80 times a second

Posted by exposed On April - 3 - 2014

The Amazing Metabolism of Hummingbirds

canada goose black friday sale Hummingbirds have long intrigued scientists. Their wings can beat 80 times a second. Their hearts can beat more than 1,000 times a minute. They live on nectar and can pack on 40 percent of their body weight in fat canada goose for migration.

Canada Goose Jackets But sometimes canada goose uk shop they are so lean that they canada goose clearance live close to caloric bankruptcy. At such times, some hummingbirds could starve to death while they sleep because they’re not getting to eat every half hour or so. Instead they enter a state of torpor, with heartbeat and body temperature turned way down to diminish canada goose store the need for food.

canada goose clearance Kenneth C. Welch Jr. at the University of Toronto, Scarborough has studied the metabolisms of hummingbirds for more than a decade. His most recent research Canada Goose Parka with Derrick J. E. Groom, in his lab, and other colleagues is on the size and energy efficiency in hummingbirds. By using data on oxygen consumption and wing beats to get an idea of how much energy hummingbirds Canada Goose Outlet take in and how uk canada goose much work they put out, the scientists found that during strenuous hovering flight, bigger hummingbirds are more efficient energy Canada Goose Coats On Sale users than smaller ones. The research was published in Proceedings of the Royal Society B.

canada goose clearance sale Excerpts from a telephone conversation with Dr. Welch have been edited for clarity and length.

Canada Goose online Q. You manage to get hummingbirds to voluntarily put their heads in masks while they hover and feed. How in the world do you do that?

canadian goose jacket Q. And what are you watching for?

canada goose deals A. We’re measuring oxygen consumption rates. So I can say, ‘This buy canada goose jacket cheap human athlete is consuming four milliliters of Canada Goose online oxygen per gram of body weight per hour.’

A hummingbird can easily hit 40 milliliters of oxygen per gram per hour. And if I ask the hummingbird to do extra, canada goose uk outlet if I give it a little bit of extra weight to wear, that can go up to well above 60. So, their tissues are using oxygen at rates that are many, many times what we can possibly achieve.

Canada Goose sale Q. And they need the oxygen to help them metabolize the relatively enormous amounts of sugar they are taking in to get the energy to power their muscles?

canada goose store A. I did a calculation Canada Goose sale back in graduate school. It Canada Goose Online turns out that when they’re hovering around and foraging during the day, they’re pretty much exclusively burning the sugar that they’ve been eating in the last 30 minutes to an hour. And so, they have this incredible ability to move sugar through their system. I haven’t actually tried to do this. My doctor advised against it.

Canada Goose Outlet Q. So they move sugar canada goose black friday sale through their system an awful lot faster than we do?

A. Unlike us, hummingbirds can use canadian goose jacket the glucose that they’re ingesting in nectar and can move it through their guts, through canada goose uk black friday their circulatory system, and to their muscle cells so fast that they can essentially keep that pipeline going in real time.

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You and I can’t do that. We can support some small portion of Canada Goose Jackets exercise with newly ingested glucose, about 30 percent. But what’s just as remarkable is that the diet of canada goose coats hummingbirds is nectar and that’s half glucose and half fructose.

canada goose coats on sale Fructose is getting a lot of bad press these days because of high fructose corn syrup in the Western diet and its association with metabolic disease and obesity. We’re not good at using fructose at all. Hummingbirds can use that fructose at very high rates.

Q. How do canada goose sale they do it?

buy canada goose jacket cheap A. Birds and nectar feeding bats have evolved the ability to enhance the flux of nutrients like small sugars like fructose and glucose or amino cheap Canada Goose acids to more effectively absorb their food. And getting them to their tissues is enhanced because hummingbird muscles and hummingbird hearts and hummingbird blood vessels are so good. The hummingbird heart rate is high and it’s pumping so much blood per unit of time. They canada goose clearance sale have lots and lots of capillaries that allow the blood to get up close and personal to their muscle cells.

canada goose And hummingbirds can apparently take up fructose in their cells, and we’re trying to figure out what enables that. We do know that there is a different form of glucose transporter that is a specialist at taking up fructose. In our muscle cells that transporter is barely present. But hummingbird muscle fibers tend to have a lot of this transporter. So, we think we’re a little closer to understanding how they can take up fructose so fast. But the story’s not uk canada goose outlet yet cheap canada goose uk complete. We need to do some follow up work in order to really confirm that.

Q. What about your recent work on whether big or small canada goose coats on sale hummingbirds are more efficient at energy use?

A. Hummingbirds really do vary in size. buy canada goose jacket Our Ruby throated hummingbirds weigh less than a penny, 2.5 to 3 grams. Down in South and Central America, you canada goose factory sale can find some much larger hummingbird species. Up in the range of 10 12 grams. And then there’s one species, the giant hummingbird, that sits at about 18 20 grams.

buy canada goose jacket In essence, larger hummingbirds have higher efficiency. They’re converting a greater proportion of their sugar energy into mechanical power to hover than our smallest hummingbirds.

Canada Goose Parka We think a lot of it probably has to do with the speed at which the muscle fibers need to shorten in order to power those wing beats. Small hummingbirds beat their wings at a higher frequency than larger hummingbirds. It’s something they need to do to generate sufficient mechanical power. But the faster you move or the faster you make a muscle shorten, there is evidence that suggests the less efficiently it does so.

And so, what we see is that the apparent efficiency of the smallest hummingbirds is down around 10 percent. If you go up to the larger hummingbirds they are they’re up in the range of, you know, 30 percent.

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