I was sitting in the garden, looking up at the sky, waiting for an exciting bird to fly over, when, as you do, I started thinking about how many feathers there are in the world.
Now I’m not thinking about the ones in duvets, pillows or jackets, I’m thinking about live feathers attached to live birds. There are some flying over now, making the smooth outline of a Black-headed Gull (and its chocolate-brown head)!
How many do you think? No, don’t just shrug and say you don’t know! I don’t know either, but we can have a good guess, and this is fun.
I’m guessing high trillions as my starting point. How about you?
Big numbers aren’t that meaningful to us in our daily lives. I find that once we are talking about numbers bigger than roughly the number of players and officials on a rugby union pitch they blend into each other.
A trillion is 1,000,000,000,0000 – a thousand billion and a million million. It’s a very big number.
But there are 10,000 species of birds in the world and if they were all as numerous as the most numerous bird in the world today (the Red-billed Quelea, population c1 billion [note to self – is it a billion individuals or a billion pairs? In the end it won’t make much difference but best to check. I think it is a billion individuals]) then there would be 10 trillion birds and they must have hundreds or thousands of feathers each so that would take us beyond trillions to quadrillions. Maybe high trillions is on the low side. Let’s see.
I happen to have the population size of the Red-billed Quelea lodged in my mind because I wrote a book on the previous holder of the record of the world’s most numerous bird, the Passenger Pigeon, which was even commoner. But I don’t know the population size of many of the other bird species in the world. Hmmm.
If the other 9,999 species were practically extinct (as some are) then the billion individuals [I checked – it is individuals] spread over all species would mean that the average population size for birds would be 100,000 individuals. That’s a useful benchmark – the real average population size for birds on Earth must be above 100,000 individuals. So if each bird has 1,000 feathers (do you think it does?) then there would be 100 million feathers in the world.
How, sitting in the garden, do I get a better estimate of the number of birds in the world? I wonder how many birds have a world population of a million individuals (that’s only 500,000 pairs). There must be loads! If there are a thousand of them then they add up to the equivalent of another Red-billed Quelea population. I’m guessing there are more, possibly far more than a thousand species with a world population of more than a million individuals.
One of them is singing now – a Wren. I think I remember there being about 8 million pairs of Wrens in the UK – our commonest bird. So, I can think of the UK Wren population alone contributing the equivalent of 16 species with a million individuals in the world. Off the top of my head I think I can remember that the following species’ UK populations are greater than a million pairs: Woodpigeon, House Sparrow, Starling, Chaffinch, Greenfinch, Goldfinch, Blue Tit, Great Tit, Rook, Jackdaw, Carrion Crow, Blackbird, Song Thrush, Robin, Skylark and Meadow Pipit. 16 species? I expect there are about 25 in that case. 25 species in the UK with average populations of, say, 2 million pairs, and four million birds. That’s the equivalent of 100 million (one tenth of a Red-billed Quelea population) from those 25 species in the UK alone.
OK, big breath!
100 million from those 25 species in the UK alone. Let’s say 150 million birds in the UK altogether. How many in Europe? Europe is a big place. Let’s say 40 times as many in the whole of Europe? That’s 6 billion. Same again Australasia? And three times as many in each of Asia, Africa, and North and South America? That’s 84 billion birds on Earth. I wonder whether that’s right. It won’t be exactly right, to the individual bird, but is it right-ish? To within an order of magnitude? Two?
How many feathers does a bird have? I don’t know. It must certainly be more than 100 and it will be less than 100,000. Do big birds have more feathers than small birds? I guess so, but I’m guessing about 10 times as many not 100 times as many. What’s a reasonable number of feathers for the average bird? Stab in the dark – 5000?
84 billion birds with 5000 feathers each – 420 trillion feathers flying around the world?
Oh look, there’s one falling from the sky now…
I wonder how many interesting birds flew over while I was thinking about that?
…to be continued.
[registration_form]
This reminds me of questions my kids used to ask in the car on a long drive. Are there more tree leaves or blades of grass in the world was an old favourite. Still not sure about that one.
Another aspect of feathers is that they are a masterpiece of engineering. Much better in many respects than the ordinary hairs of mammals. Feathers have a very ancient history. They were clearly visible on the famous fossil archaeopteryx found in Germany. The fossil showed an animal half bird and half dinosaur and which was about 150 million years old, that is mid Jurassic time. One of the features of archaeopteryx feather impressions showed that its feather arrangement (primaries, secondaries etc ) was just the same as those of modern day birds. Recent fossil finds in China show that animals that are clearly non flying dinosaurs also had feathers, showing that beyond doubt our birds today are in fact dinosaurs that survived the big extinction 65 millions years ago at the end of the Cretaceous period. So dinosaurs are alive and reasonably well today. The feather is just a master piece of evolutionary engineering and must have started to evolved when the dinosaurs appeared on Earth about 230 million years ago. So next time you pick up a feather just contemplate what amazing results evolution can produce.
I do sympathise, lockdown is getting to me also.
Found this on the web:-
‘The number of feathers on a bird varies according to the species, its age, and the season. Most small songbirds have between 1,500 and 3,000 feathers on their bodies. A swan, however, might have as many as 25,000 feathers. A bird of prey, such as the eagle, would have between 5,000 and 8,000 feathers.’
Courtesy Grid Club.com
It’s an interesting conundrum, but also, and did you think of this Mark, an interesting habitat. Yes, a habitat. A habitat for feather lice and quill lice (Acari, Syringophilidae). And also for a weird family of flies: keds or flat-flies (Diptera, Hippoboscidae).
So, trillions, if not quadrillion, of feathers also mean many millions of lice and weird flies. Flying over your head as you contemplate the numbers!
Talking of big numbers and how hard it is for them to be meaningful to us, I came across a statistic about the size of molecules: there are about as many molecules (or atoms) in a teaspoonful of water as there are teaspoons of water in the Atlantic Ocean. I worked it out from the published figures and it looks like it’s pretty close. That brings home rather well how small atoms are (a teaspoon is c.5ml btw).