I have a story to relay in the hopes of preventing further incidents like this one. Keegan, our GCC, has newly grown wings and had been taking to flying on top of a wardrobe where we keep luggage. I didn't see anything wrong with this as long as I was in the room. Then, one day I heard chewing while he was up there. I climbed up to see him surrounded by white powder. My wife and I had deduced that he ate half a 300mg lithium pill. He must have found a stray one in the outside pocket of one of the bags. We called an animal toxicity hotline, and they told us to rush him to the hospital. We did, hysterical, and expecting the worst. At the animal hospital he regerged before they had a chance to clean out his crop. There were no pill fragments in what he spit up. They kept him for an hour but, to our indescribable relief, he never got sick. No one heard of a case of a bird eating lithium. We took him home and it was if nothing had happened. Our best guess is that lithium is not very toxic to GCCs and that he probably only crushed the pill into a powder without ingesting very much of it.
The moral is always check a new area before letting a bird go there even if you don't think there is anything dangerous. Another lesson is that a GCC will chew something up even if it tastes horrible.