The green warbler alternatively named green willow warbler or green leaf warbler (Phylloscopus nitidus) is a leaf warbler found in the Caucasus Mountains in southcentral Europe.Like all leaf warblers, it was formerly placed in the "Old World warbler" assemblage, but now belongs to the new leaf-warbler family Phylloscopidae. It is most closely related to the greenish warbler but is brighter in color, and the underside is much more yellow.