Birds have to have hard objects (grit, gravel, BBs, etc) to grind up their food into usable form. They can not distinguish between a coffeebean, smartweed seed, pebble, rice, etc. it all goes down. This was/is one of the bad things about lead shot, there is still hundreds of TONS of lead shot in many of the historic waterfowl wintering zones such as Catahoula Lake, and it is there from now on
