Reproduction of the head or white or black, gray or all brown all winter in the head stripes or a clear Hard beak, slightly clasp, and some species also have a colour patches.

• 繁殖期头部或纯白，或全黑、全灰或全褐；冬季头部出现条纹或不清晰的斑点。喙坚硬，略呈钩状，有些种还具一个色斑。