Sandhill-crane Fact #3: Cranes are omnivorous and their diet varies depending on the season and where they are at. The cranes that visit the Platte River valley feed primarily on waste grain left in corn fields, making up 90% of their diet while here. The other 10% comes from plant and animal foods found in wet meadows adjacent to the river. Seeds, fleshy tubers of plants, grubs, earth worms, snails, amphibians, small reptiles and small rodents are all fair game.