How does this bird know?

Today for lunch I went to the park near Wynyard Station, sat down on a bench, had my lunch and read a magazine. About twenty minutes into it, an Australian Ibis (http://en.wikipedia.org/wiki/Australian_Ibis) came along and started rummaging around in the debris alongside and behind the bench I was sitting on, looking for something to eat.

This bird was close, within arms-reach, and appeared quite unafraid of me. Even a thing that looks a frightening cross between a chicken and buzzard should be a little scared of a human.

In case you didn't follow the link above and see the pretty photograph, the bird has a long, curved, black beak, this one at least 20cm long. It was hunting around in the collected debris from the trees and rubbish, using the end of it's beak, and eventually turned up a piece of meat from a sandwich or something.

It occurred to me: how does the bird know whether the thing that it has captured in its beak is a morsel of food or not, say, a cigarette butt? Does it have taste buds right down the end of its beak? Looking closely, it seemed to have long nostrils embedded in the upper beak up near its wrinkled, black face. Obviously it can smell the food in the first place, but does the smell determine what gets picked up? Does the tongue stretch all the way down the length of the beak?

How does it do it?