The male passenger pigeon
I’ve been pondering a rather remarkable fact lately, since learning that passenger pigeons — extinct for about 100 years now — used to number in the several billions. The remarkable thing is that they used to fly around in flocks which were estimated at more than a billion, perhaps over three billion. ‘Flock’ may be too small of a term for that size group.
The bird’s name comes from the French word passager, to pass by. Which these birds could do at a blazing 60 mph.
Here’s an entertaining essay that describes the scene in the U.S. a couple hundred years ago (LINK). Try to imagine being outside one day when a billion birds fly over. For hours and hours. I think it’d be fascinating, and I’d be tempted to lie down on the grass and watch. But it wouldn’t take long to decide that it’s wiser to watch from under some protection, like a tree.
Here’s a curious observation about passenger pigeons that helped lead to their demise once hunting limited their population: “This was a highly gregarious species—the flock could initiate courtship and reproduction only when they were gathered in large numbers; it was realized only too late that smaller groups of Passenger Pigeons could not breed successfully, and the surviving numbers proved too few to re-establish the species.” [a],[b]
In other words, this species took the concept of group-dating to a whole new level (or, to new heights). And it raises an interesting variation on the chicken-or-egg problem: Which came first, 1 billion passenger pigeons or a billion eggs? These critters didn’t seem inclined to populate from small numbers.
Billions
All this got me to wondering: how often, if ever, do I encounter things that number into the billions? There are several billion people on the planet, but on a normal day I probably encounter a thousand or less. Going to an event like a ball game or concert could push that up to tens of thousands.
If you want to find a billion of something one day, it needs to be small sized. It’s easy enough to be around billions of molecules, although they’re a bit hard to see. Grains of sand is a good choice. I estimate that in a moderate sized sandy beach, there are probably more than a trillion grains of sand, and about a billion of them lying on the surface so in a sense you can more or less see them all at once. (For the curious, see calculations below.)
Tree leaves are a candidate for encountering a billion in a day. I live on a greenbelt and so I spent some time estimating leaf count per tree. This varies widely with tree type and size, of course. I estimated perhaps 5,000 to 10,000 per moderate sized tree, and maybe 10 – 20 times more, up to 200,000 on the big trees. Here’s a panoramic shot out back, with the world curving the wrong way due to the panorama stitching effect.
There are a lot of trees in this greenbelt, as shown in the satellite picture of the area, below. It would take more than 10,000 trees at these (wild) estimates to make the billion — might be possible. So a day of strolling through such forested areas should put one in the presence of a billion leaves. Not bad for finding a billion of something that big.
Rule of thumb: People, Ants, Stars
Critter wise, there are a lot more ants on the earth than there were ever passenger pigeons — many quadrillions, but you’re not going to find a billion in one day (hopefully). But here’s a very handy rule of thumb. With about 7 billion people on earth, something in the vicinity of 100 quadrillion ants, and something in the (very large) ballpark of 70 sextillion stars (70,000,000,000,000,000,000,000) in the universe, a handy (and very approximate) way to relate these is:
For every person on earth, there are about 10 million ants.
For every ant, there are about 10 million stars.
It’s simple to remember: just imagine each person covered by 10 million ants, and then each ant associated with 10 million stars.
Estimates: Red tree, 5000 leaves. Big tree, 150,000 leaves.
By the way: remember that Carl Sagan, famous for the phrase “billions and billions” didn’t actually use this phrase (link). This reminds me of a time when Logitech discovered, through customer surveys, that they were thought to be #2 or #3 in the world in keyboards, before they had actually entered that market. This is a good strategy — whenever possible, dominate a market before entering it.
Also, this post is dealing with the “true” billion, the one with 9 zeros (1,000,000,000). Some of the Europeans have developed a bad habit of sneaking in a few extra zeros for a billion (1,000,000,000,000) — see this article (which also includes the important misinformation about Sagan’s billions and billions phrase). Maybe this has something to do with the debt crises there.
Have a favorite thing that you encounter in the billions? Leave a note so we can go looking for more billions and billions.
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Calculations: Taking an average sand grain as having diameter = 1 mm. On a beach that’s about 100 yd (or meters) by 25 yards by 8 inches deep with sand:
# grains of sand total = Volume of beach / Volume of sand grain = (100 * 25 * 0.2 m3 * 109 mm3/m3) / ((4*pi/3)*(0.5mm)3) = approx 1 trillion.
# grains on beach surface = Area of beach / Area of grain = (100 * 25 m2 * 106 mm2/m2) / ((pi * 0.5mm)2) = 3 billion
