It's about tiny percents.
A bird will land on a flower.
A bird will not land on a bird.
So every one in a million time a bird mistakes a flower for a bird, that's a flower that survives.
All you have to do is wait a couple million years for the odds to turn in the bird flower's favor.
I never really found a use for this. Do people really need so many tabs open they have to sort them?