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Vultures, you eat old, putrid dead things for a living. How is that not killing you? Hank explains the secret weapons vultures use to fight off disease, avoid predators, and beat the heat. Prepare for a Sci-Show Gross-Out!

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Sources for this episode:
http://indianapublicmedia.org/amomentofscience/vultures-food-poisoning/
http://www.madsci.org/posts/archives/2000-09/968529176.Bc.r.html
http://animaldiversity.ummz.umich.edu/accounts/Cathartes_aura/
http://www.scienceandnature.org/IJSN_Vol3(2)J2012/IJSN-VOL3(2)12-4R.pdf
http://vulturesociety.homestead.com/Vulture-Benefits.html
http://science.howstuffworks.com/zoology/birds/vulture-vomit1.htm
http://www.jwildlifedis.org/content/11/3/306.full.pdf
http://birding.about.com/od/Bird-Trivia/a/20-Fun-Facts-About-Vultures.htm
http://erie.wbu.com/content/show/25899
http://www.wisegeek.org/how-does-stomach-acid-break-down-food.htm#slideshow

 Introduction


Have you ever been digging around in your fridge late at night looking for a snack and come upon some leftovers in the back, wondering if maybe too much time has passed, but you go for it anyway because you're hungry and lazy and cheap? - yeah like college, all of college for me? - But then by the next morning you're all moaning and groaning and really regretting that decision to eat the slightly fuzzy burrito? You know who doesn't have that problem? Vultures.

 Content


(0:24) At some point in your life you've probably come across a hunched turkey vulture digging into a nice ripe smudge of roadkill and thought, "How can you eat that rotten, stinky meat and not get sick? How is that not killing you?"

(0:38) The world's 23 species of vultures have evolved the ultimate freegan palate. They pretty much eat exclusively dead things with the help of their amazing digestive systems. The stomach breaks down food using gastric juices comprised mainly of hydrochloric acid to dissolve bonds and protein molecules, and digestive enzymes that continue the dismantling process.
(0:57) The average levels of a human gastric system are between 1 and 2 on the pH scale. By way of comparison, vinegar weighs in at about 2.4 and battery acid at about 0.08. But the stomach acids of some vultures comes in between 0 and 1, so corrosive that they can dissolve certain metals. Which is super cool, but unless they're trying to eat a robotic raccoon not particularly useful. I mean it's a bit overkill for just like, dead cow stuff.
(1:22) But a festering carcass, as you might imagine, is a dirty place. It may still house whatever viruses, parasites and diseases killed the thing in the first place! That's why the birds' super strong acid cocktail is a whiz at killing a whole mass of pathogens that would be lethal to lesser scavengers; from salmonella and cholera to anthrax, botulism, even rabies.
(1:40) In addition to laying the smack-down on nasty bugs in the digestive tract and pumping blood thick with bacteria fighting antibodies, vultures have a few more tricks up their feathered sleeves to stay healthy.
(1:51) Like pooping in their pants - eh, they don't wear pants, but they do poop directly on their legs, which is a strange kind of brilliant. For one, this evaporating slurry of waste is a great way of cooling down on a hot day and for another the whitish slob contains some of that great acid, which acts as an awesome sanitizer on legs that have been knee-deep in rot.
(2:11) Not only that but the waste keeps killing pathogens in the grass around the carrion, helping to prevent the spread of disease to other animals and even to soil and water systems. The vultures are kinda like a HAZMAT cleanup crew.
(2:25) A vulture's bald head also keeps it clean. Since they gotta get all up in the mushy chest cavities and guts their heads get pretty grody. A feathered crest would house more bacteria-ridden flesh crumbs than Methuselah's beard, whereas a clean pate stays more hygienic and gets baked clean under the hot sun.
(2:42) Oh, and if you've heard the tale that vultures projectile vomit to protect themselves from predators, know that this is only half true. They do indeed produce an impressive hurl storm, but it probably isn't to spew rabies in coyotes faces.
(2:55) Although vulture vomit may burn those unlucky enough to get splattered, it's probably more to do with the fact that they've gorged so much on meat that they're too heavy to quickly lift off, and thus need to lighten the load.
(3:06) In any case, at that point any potential predator would presumably think, "Oh! Hot acid vomit!" and leave the bird alone. Excellent. So anyway, next time you feel like vultures are gross, just remember that, in addition to being gross, they also are really amazing.

 Outro


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