In the jungle, as in the cage...

I've always said that a parrot's job is to take the top third of the rain forest and move it down to the bottom third. In this interview, “Dr. Lee” Simmons spells out the same idea a bit more clearly:

Q. What is the role of parrots in the ecosystem?

A. The way I see the job of parrots, particularly in the rain forest where the food is high in the canopy, parrots eat seeds, fruit, a lot of things. But parrots are sloppy eaters. They will pick up a piece of fruit, take a bite and let the rest fall down below. One day it hit me, they are throwing it down to the ones below. In the Amazon on the ground it is dark. It gets lighter as you go up through the trees and much of the activity is in the canopy. The parrot food also sticks at different levels, so that is their job to pick for everyone below them. I don’t know what the job of parrots in the desert might be.

Either way, it goes a long way towards explaining why 90% of thier food ends up at the bottom of their cage.
Read the whole interview here: Parrots have a role in rain forest.