Owls come in many shapes and sizes, ranging from the 5 to 6 inch average length of tiny elf owls to the imposing 25 to 30 inch size of great horned owls. Most owls have patterns in their plumage that help them blend in with their environment. Great horned owls have mottled brown feathers that grow white beneath their wings, large yellow eyes, and plumicorns atop their heads, which resemble a pair of horns. Barn owls, on the other hand, have white or light gray plumage on their faces and breasts and brown wing feathers mottled with gray spots. They have heart-shaped faces with a pair of strikingly dark eyes. Their long, soft feathers allow them to glide noiselessly through the air.