# The Naked Scientists Forum

### Author Topic: More likely to fly in or out?  (Read 2912 times)

#### SquarishTriangle

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##### More likely to fly in or out?
« on: 17/08/2008 10:12:05 »
At times I might find a fly (sometimes even a small bird) inside a room, perhaps trying to find its way out of the room without any luck. Any attempt to show it the way out (through a doorway or window) is usually of little success, at which point I resign to having to put up with a buzzing sound in the room for at least a while longer...or in the case of the bird, catching it and taking it outside. The question: Is there any difference in the likelihood of a creature flying into a room compared with the likelihood of it flying out of the room?

#### lyner

• Guest
##### More likely to fly in or out?
« Reply #1 on: 17/08/2008 10:27:05 »
All things being equal, there is a much greater probability of a bird flying out than in. If it is drawn to the window because it thinks there is some chance of food / a mate / and enemy in the room, then that could bias the situation.
But just consider the evidence; how many birds fly into windows and how often? How many birds remain trapped inside a room if the window is left open and you leave them on their own?
You may wait years / months for onew to fly in. Do you ever wait months for one to fly out?
I think it's one of those situations where it is hard to see the evidence dispassionately. (The poor little thing can always starve whilst it is in the room, of course.)

#### Bored chemist

• Neilep Level Member
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##### More likely to fly in or out?
« Reply #2 on: 17/08/2008 13:54:18 »
Almost all the time there are no birds in the room. The mean concentration is, therefore, aproximately zero birds per cubic metre.
On the other hand, the concentration of birds outside is higher than this.
Diffusion takes place to reduce the difference in concentration.
On average birds are more likely to fly in.
However, once there's a bird in any normal size room the concentration gradient will be reversed and the bird is more likely to leave than to be joined by another bird.

#### graham.d

• Neilep Level Member
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##### More likely to fly in or out?
« Reply #3 on: 17/08/2008 19:12:33 »
So now we have a partial pressure of birds :-)

Realistically, birds have brains and means to interpret their environment. Glass can confuse them, but mostly, if left alone, they can find their way out.

#### lyner

• Guest
##### More likely to fly in or out?
« Reply #4 on: 17/08/2008 21:28:53 »
Almost all the time there are no birds in the room. The mean concentration is, therefore, aproximately zero birds per cubic metre.
On the other hand, the concentration of birds outside is higher than this.
Diffusion takes place to reduce the difference in concentration.
On average birds are more likely to fly in.
However, once there's a bird in any normal size room the concentration gradient will be reversed and the bird is more likely to leave than to be joined by another bird.
Only a chemist would reduce our feathered friends to molecules!
A really 'cracking bird' might change the situation!

#### LeeE

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##### More likely to fly in or out?
« Reply #5 on: 17/08/2008 23:24:35 »
I seem to recall that in one of DNA's h2g2 books, the greatest achievement in the galaxy, in the field of genetics, was when someone produced a fly that could find it's way out of an open window.

#### The Naked Scientists Forum

##### More likely to fly in or out?
« Reply #5 on: 17/08/2008 23:24:35 »