A. Besides an assortment of weed and other small seeds that may be amongst the gravel, birds will find GRIT on your gravel driveway. Birds break down (grind) their food in a part of their stomach called the gizzard. (Just like the gizzards you get in your turkey giblets package, but smaller!)
When you see birds foraging on your driveway, they may be looking for hard gritty materials like sand and small bits of gravel or rock, which will aid in the grinding process taking place in their gizzards. The birds I see foraging on my driveway most often are doves, jays, juncos, and chipping sparrows.