Pigeon Grits & Minerals

Pigeons need grit to help with their digestive process.
As they swallow their food whole, it has to be broken down in order to get the nourishment out of it.
Pigeons just have stomachs that dissolve their food, they also have gizzards, a muscular part of the stomach.
The gizzard is essentially a food processor where the tiny pieces of grit act as grindstones to crush the whole grains, seeds, and Big Macs (in the case of the city slickers), into pulp which is then worked on by digestive enzymes.