A duckling is a baby duck. Ducklings usually learn to swim by following their mother to a body of water.
Ducklings, like all birds, hatch from eggs that are typically laid in a nest. Soon after all the ducklings hatch, the mother duck leads them to water, where most kinds of ducks spend the greater parts of their lives. One of literature’s most famous ducklings is the one in Hans Christian Andersen’s “The Ugly Duckling” — although that duckling, in the end, turned out to be a swan.