I usually don't have much of a problem sexing birds but I could use some opinions on this one from those more familiar with the breed and their development. He/she is a White Rock. I have no experience with them but know Rock pullets do tend to get large and red in the combs early. I do have Barred Rocks, and they sure did. At this age, I swore my hens were dudes. The color is a little off in the pics..the comb isn't AS red as it looks here..it's more of a peachy color at this stage. Anyways.. About 9 weeks old in these pics, taken 3 or 4 days ago: