What is the volume of a pigeon?
May 20, 2019 7:48 AM Subscribe
I've been able to find sources on approximate weight of a pigeon and how much blood a pigeon has, but what I would like to find is the mean volume of a typical, uncompressed, dry, London pigeon. (as in area that a pigeon takes up, not how loud it is).
If you want extra points I also need to find a way of estimating the approximate volume of a human being based on height.
Why?
No reason....
Oh ok. I'm trying to answer the question a neighbourhood child asked this weekend. What is the equivalent volume in pigeons to a five year old child.
If you want extra points I also need to find a way of estimating the approximate volume of a human being based on height.
Why?
No reason....
Oh ok. I'm trying to answer the question a neighbourhood child asked this weekend. What is the equivalent volume in pigeons to a five year old child.
Now if you want to teach the kid something cool, you could enlist their parents' assistance in measuring their volume using the old Archimedes-in-a-bathtub method!
posted by aws17576 at 8:00 AM on May 20, 2019 [6 favorites]
posted by aws17576 at 8:00 AM on May 20, 2019 [6 favorites]
Best answer: The paper Determination of body density for twelve bird species gives the weight of a rock dove as 323g (±46g) with a density of 0.648 ±0.032 g/cm³. This is based on catching birds near an airbase, weighing them, and measuring their volume by water displacement, but annoyingly the paper gives weights and densities (among other things), not volumes.
Anyway, by dividing the mass by the density we can therefore say that the volume of a typical rock dove is (323 / 0.648 =) 498.5cm³.
To answer your bigger question, I'd stick with densities. According to a bit of casual googling a typical human has a density of about 0.98g/cm³ (with fairly wide variance: muscle and bone are heavier, fat and air spaces are lighter). So we can just say:
Pigeons per human = volume of human / volume of pigeon
Pigeons per human = (weight of human in grams * 0.98) / 498.5g
For example, if the human weighs 50kg we convert 50kg to 50,000 grams then:
(50,000 * 0.98) / 498.5 = 98.3 pigeons
posted by metaBugs at 8:33 AM on May 20, 2019 [8 favorites]
Anyway, by dividing the mass by the density we can therefore say that the volume of a typical rock dove is (323 / 0.648 =) 498.5cm³.
To answer your bigger question, I'd stick with densities. According to a bit of casual googling a typical human has a density of about 0.98g/cm³ (with fairly wide variance: muscle and bone are heavier, fat and air spaces are lighter). So we can just say:
Pigeons per human = volume of human / volume of pigeon
Pigeons per human = (weight of human in grams * 0.98) / 498.5g
For example, if the human weighs 50kg we convert 50kg to 50,000 grams then:
(50,000 * 0.98) / 498.5 = 98.3 pigeons
posted by metaBugs at 8:33 AM on May 20, 2019 [8 favorites]
the mean volume of a typical, uncompressed, dry, London pigeon. (as in area that a pigeon takes up, not how loud it is).
I think what you are looking for is the visual displacement not the 'plucked' displacement which is used above. If you have ever bathed a cat or seen pictures of a bird emerging from an oil slick, you'll know that fur/feathers take up a lot of volume which is not accounted for in the volume calculations above which are based on body density I believe.
In other words, I think what you are looking for is the displaced volume of something like a ceramic pigeon model?
posted by vacapinta at 8:53 AM on May 20, 2019
I think what you are looking for is the visual displacement not the 'plucked' displacement which is used above. If you have ever bathed a cat or seen pictures of a bird emerging from an oil slick, you'll know that fur/feathers take up a lot of volume which is not accounted for in the volume calculations above which are based on body density I believe.
In other words, I think what you are looking for is the displaced volume of something like a ceramic pigeon model?
posted by vacapinta at 8:53 AM on May 20, 2019
Response by poster: I've used metabugs data for pigeons, since it does list dry unplucked density.
I've actually not used the oft reported 0.98 figure for human density.
I used a slightly higher estimate from a 1966 study that was more referencable.
In conclusion, an average five year old has the same volume as around 34 pigeons. Which seems like a plausible figure.
posted by Just this guy, y'know at 9:18 AM on May 20, 2019 [6 favorites]
I've actually not used the oft reported 0.98 figure for human density.
I used a slightly higher estimate from a 1966 study that was more referencable.
In conclusion, an average five year old has the same volume as around 34 pigeons. Which seems like a plausible figure.
posted by Just this guy, y'know at 9:18 AM on May 20, 2019 [6 favorites]
Maybe think in terms of everyday objects of known volume.
For a pigeon: could you fit one into a pint glass? Answer: probably, if you squish it a bit. So - roughly half a litre.
For no. of pigeons per small child: could a small child fit into my largest backpack? Depends on the child I guess, but I think the average 5yo should be able to get inside, curled up. That's 70 litres.
So that method would give a somewhat larger number than 34. You can use whichever method gives you the most teachable / helpful / memorable explanation for the child in question.
posted by rd45 at 10:50 AM on May 20, 2019 [3 favorites]
For a pigeon: could you fit one into a pint glass? Answer: probably, if you squish it a bit. So - roughly half a litre.
For no. of pigeons per small child: could a small child fit into my largest backpack? Depends on the child I guess, but I think the average 5yo should be able to get inside, curled up. That's 70 litres.
So that method would give a somewhat larger number than 34. You can use whichever method gives you the most teachable / helpful / memorable explanation for the child in question.
posted by rd45 at 10:50 AM on May 20, 2019 [3 favorites]
Response by poster: My calculations have a pigeon coming out at around 560 ml.
So your estimate of pigeon volume is genuinely impressive.
posted by Just this guy, y'know at 2:19 PM on May 20, 2019 [1 favorite]
So your estimate of pigeon volume is genuinely impressive.
posted by Just this guy, y'know at 2:19 PM on May 20, 2019 [1 favorite]
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Since density = weight/volume by definition, rearrange to get volume = weight/density. Plug in your weight estimate and a density estimate from the article linked above. (You may also have to convert units.)
For the human being, height is going to be a lot less predictive than weight, but there are probably places to look up average weight by height and age. The density of a human being is going to be just a hair under 1 g/ml, given that we're just slightly buoyant in water.
posted by aws17576 at 7:58 AM on May 20, 2019 [1 favorite]