I got these from fleet farm, looks like you can also get them on amazon. They are a treat dispenser which you can dial the size of the opening, kind of like the yellow chicken treat balls, only these won't allow the chicken to crack them in half, so they have to move the ball around and not cheat. Plus they can see what is in there through the semi transparent plastic. They work great! Here is a link to the amazon one, more photos at the bottom of the link, then a couple photos of the one of the ones I got:
http://www.amazon.com/Petsafe-SlimCat-Meal-Dispensing-Blue/dp/B0018CG40O
Penned up birds need a lot of entertainment - swings, chairs, perches, treat balls, dust-bath tub, etc. I saw one owner use a clear water bottle to make her own treats bottle for her 2 pet chickens. They saw the seed inside the clear plastic and kept pecking at it until the seed spilled out of the small hole on the side. They can peck at the soft plastic sides and the bottle rolls around to distribute the seeds a little at a time.