Bird grit for ornamental birds Bird grit contains a mixture of different elements including oyster shells, redstone, stomach gravel, limestone and charcoal. It is an important supplement for the daily diet of birds and pigeons. Witte Molen PLUS grit is packed full of calcium, which supports the structure of the skeleton. Bird grit contains phosphorus, a mineral which promotes strong bones. It is also important for healthy digestion, as it helps to break down grains and seeds, making it absolutely ideal for your pet!