Limestone Leaf Warbler Phylloscopus calciatilis NOT YET EVALUATED Beginning in 1994, ornithologists began to notice birds thought to be the Sulpher-breasted Warbler (P. ricketti) in breeding condition, singing, in what was their wintering range in Laos. Upon more detailed study, they realized these warblers represented a unique taxon. The plumage was nearly identical to P. […]