It's not easy to tell the difference between a barred Plymouth Rock and a silver cuckoo Marans. The "cuckoo" type of the latter bird doesn't refer to sound or personality, but to the barred feather pattern. The coloration of both of these barred breeds includes a white base coat with feathers crossed with light and dark gray bars.
Barred Plymouth Rock History
The Plymouth Rock breed dates back to the Civil War era, when an earlier breed, the Dominique, was crossed with solid black hens. The resulting chicken was heavier and a solid dual purpose type for meat and egg production. Up until World War II, the Plymouth Rock was the most common chicken in the United States, according to Mother Earth News. The late 19th century saw the development of the white Plymouth Rock, which became a prominent meat breed.
Named for the town in France from which they originate, Marans are relatively rare in American flocks. Marans are used primarily for egg production. While the earliest Marans sported leg feathering, that trait rarely crops up in modern birds. The coloring of the male cuckoo Marans is considerably lighter than the females -- it's possible to tell the gender as soon as the chicks sprout feathers. Other Marans colors include golden cuckoo, black, white, blue, wheat, ermine, coppered black and black-tailed fawn.
If you've acquired a hen and aren't sure whether she's a barred Plymouth Rock or a cuckoo Maran, her eggs should reveal her lineage. While Plymouth Rock hens lay brown eggs that vary in hue from light to dark, the Maran lays a dark, chocolate-colored egg. The egg color depends on the hen, not whether she mated with a particular rooster. Not only are the Marans' eggs very dark, they also tend to be more spherical in shape than other breeds.
Plymouth Rocks and Marans are approximately the same size, maturing between 7 and 9 pounds, so size doesn't help you differentiate the breeds. They're both breeds with single combs. Observing their behavior can help you figure out the type of chicken. Marans aren't particularly friendly or docile birds, while Plymouth Rocks are generally pretty tame. If you don't care about egg color and desire a calmer, more "pet" type of chicken, the Plymouth Rock makes the better choice.