Was it possible for Andy Warhol to see a living passenger pigeon?
No, he could not. The last of the species died in a zoo in 1914.
How many passenger pigeons were there in one flock?
Many flocks contained over one or two billion birds.
What is the difference between a passenger pigeon and a regular pigeon?
The main difference is that passenger pigeons are extinct. Also, regular pigeons now are much less attractive in color that passenger pigeons were.