Identifying duckling breeds can be a daunting task for a novice duck owner. A reputable duck breeder will tell you the breed of your duck as well as the colouration it will likely have as an adult. If you've rescued a duck or are otherwise unsure of the breed, most duckling breeds can be identified based on a combination of colour, pattern and body shape.
Watch the way the duckling carries itself. Most ducks have squat body postures with their necks craning slightly backward. Indian runner ducklings, however, are known for their erect body posture. If your duckling walks upright most of the time, with its head straight up, it's likely an Indian runner.
Observe the colour of your duck. Solid yellow ducks are most likely to be pekins, an common duck breed. They may also be buff ducks, but these ducks are not frequently kept as pets. Black and yellow ducks are likely mallards, rouens, Muscovy or wood ducks. Brown and black ducklings may be geese.
Look at your duck's bill. Most ducklings have yellow bills. Rouen, Muscovy, and mallard ducks, however, have brown or black bills.
Examine the pattern of your duckling's markings. Ducklings with thick, clearly defined bands of black or brown may be geese or swans. Brown and yellow ducks with a brown stripe near the eye are mallard, rouen, or wood ducks. Wood and rouen ducks are less common pet choices than mallards, so it is most likely that ducks with this pattern are mallards. Ducks that are completely black or brown with a yellow chest and small yellow spots at the wings are most likely blue Swedish ducklings.
Ask an avian vet to identify your duck. Ducklings can typically be narrowed down to one or two species based on colour. An avian vet will be able to look at behaviour, bone structure and other factors in order to definitively identify your duck.
Identifying the breed of your duck can help you to construct the right enclosure, feed the right diet, and plan for its adult size and temperament.