Naked Science Forum
Life Sciences => Plant Sciences, Zoology & Evolution => Topic started by: Edge03zn on 10/12/2013 14:39:37
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Why is bird scat black and white, while everyone else's is brown.
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Why is bird scat black and white, while everyone else's is brown.
I must say that question has evoked a very humorous reaction from myself if not from others here at NSF. But to answer your question my friend:
It all boils down to the chemical composition of the scat and how the spectrum of light is absorbed by it. If you have the courage to test a sample of so-called scat, you'll find your answers there. As for myself, I'd be happy to let you preform that task all by yourself.
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Nitrogen-rich compounds formed from protein chemistry must be excreted by both mammals and birds. Mammals excrete this in the form of urea (dissolved in urine). Urea is toxic, and so must be diluted by large amounts of water.
Birds have one opening for elimination of indigestible food, urea and for laying eggs: the cloaca.
Birds excrete waste nitrogen compounds in the form of uric acid crystals, which is seen as a white paste in bird droppings, mixed with material which has passed through the digestive system.
Humans can also produce uric acid, but lack an effective way to excrete it, so it can build up in joints, leading to gout (http://en.wikipedia.org/wiki/Gout#Signs_and_symptoms).
See: http://www.holisticbirds.com/pages/urinarysystem0503.htm
This suggests that urea buildup would be lethal to a chick inside an egg, while uric acid is a safer way to sequester the waste nitrogen until the chick hatches. On the other hand, mammals can flush out nitrogen compounds from a fetus by passing the soluble compound urea across the placenta, and out via the mother's kidneys.
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Why is bird scat black and white, while everyone else's is brown.
The short answer is - it isn't. As someone who has to park their car under a tree, I know bird droppings are multicoloured, depending on the particular berries they're eating at various times of year. It's true that a lot are monochrome, but not all by any means.
Mammalian scat is typically brown because that is the colour of the breakdown products (mainly stercobilin (http://en.wikipedia.org/wiki/Stercobilin)) of the red haemoglobin from the blood, broken down by the liver, and excreted in bile.
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Why is bird scat black and white, while everyone else's is brown.
The short answer is - it isn't. As someone who has to park their car under a tree, I know bird droppings are multicoloured, depending on the particular berries they're eating at various times of year. It's true that a lot are monochrome, but not all by any means.
Mammalian scat is typically brown because that is the colour of the breakdown products (mainly stercobilin (http://en.wikipedia.org/wiki/Stercobilin)) of the red haemoglobin from the blood, broken down by the liver, and excreted in bile.
Interesting subject, this site gives more info on other than brown colors, in some cases diagnostic of medical conditions (Stool color: When to worry http://www.mayoclinic.com/health/stool-color/AN00772 (http://www.mayoclinic.com/health/stool-color/AN00772)), or what you've been eating. Bingeing on black licorice yields dark green for some.
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Interesting subject, this site gives more info on other than brown colors, in some cases diagnostic of medical conditions (Stool color: When to worry http://www.mayoclinic.com/health/stool-color/AN00772 (http://www.mayoclinic.com/health/stool-color/AN00772)), or what you've been eating. Bingeing on black licorice yields dark green for some.
Interesting... but I think I'll pass [;)] (that might have been a pun!)
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Why is bird scat black and white, while everyone else's is brown.
all kidding aside, great question.
Interesting... but I think I'll pass [;)] (that might have been a pun!)
Indeed, science allows us to boldly go where others fear to tread.
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Indeed, science allows us to boldly go where others fear to tread.
Eeew [;D]
Pulls on the boots of science, with their woo-proof soles of skepticism, over the cosy socks of critical thinking, and ties tight the laces of reason...