Ruby-crowned kinglet
（重定向自Regulus calendula）
The ruby-crowned kinglet (Regulus calendula) is a very small passerine bird found throughout North America. It is a member of the kinglet family. The bird has olive-green plumage with two white wing bars and a white eye-ring. Males have a red crown patch, which is usually concealed. The sexes are identical (apart from the crown), and juveniles are similar in plumage to adults. It is one of the smallest songbirds in North America. The ruby-crowned kinglet is not closely related to other kinglets, and is put in its own subgenus, Corthylio. Three subspecies are currently recognized.