duck food

My feathered friends stage a fowl food heist every single day

Every single day, my feathered friends stage a fowl food heist. My chickens and ducks have lived peacefully for about a year, separate houses, separate runs, but they free range together. I leave both runs open so everyone can grab food, water, or a nesting spot. The chickens always have their own layer feed from Tractor Supply. Yet every day, they devour all the duck food and ignore their own. I hardly ever refill the chicken feed. They only touch it at sunset, when they get locked in. Why the duck-food obsession? The calcium is higher, but otherwise it's less nutritious. None of their eggs show low-calcium signs. I doubt it's just taste. Maybe they're fowl play connoisseurs?