Cleansers wash off the soybean oil and fuel oil, but also remove the ducks' natural oil which keeps them buoyant in water. A few ducks got away from their rescuers after being cleaned, and drowned quickly after reaching the water. The ducks must be kept in captivity until summer, when they will molt and develop new feathers.
Image from the Hastings Gazette Weekly, April 4, 1963, p. 2. Digitized with permission from the Hastings Star Gazette.