Curlybird:
Wow - that was fast! How do you identify these young gulls? Is it just from experience?
Gulls are one of the most difficult groups for everybody, both because some species are so similar, and because they have so many intermediate molts. Start with what's common in your range. It helps to get a photo which you can then later compare with references. An excellent reference is
Gulls of the Americas by Howell & Dunn, a beautiful comprehensive book with hunderds of color plates. It deserves to be high on the list of references any serious birder would want on his/her shelf. There, with some patience, you can almost always find a photo or two that matches closely with the one you are trying to ID.
