If you get chicken feed wet, it turns to mush. In the bird, this same thing happens and the gizzard really doesn't need to "grind" the food up.
Most other things a bird eats won't soften like that. As stated, any grains/seeds/greens, any meat or bugs, pretty much anything but something like yogurt they'll need grit to start digestion.
Most other things a bird eats won't soften like that. As stated, any grains/seeds/greens, any meat or bugs, pretty much anything but something like yogurt they'll need grit to start digestion.
