Here is a warbler with a strong infusion of dull green to the upperparts. That should already point you to a Phylloscopus (leaf) warbler or perhaps one of the greener species (Melodius or Icterine). But neither Hippolais has a dark eyestripe. So this looks to be a leaf warbler. The prominent wing-bar rules out Chiffchaff and Willow Warbler and, additionally, the green tones rule out the brown Dusky and Radde’s Warblers. Yellowbrowed and Hume’s Leaf have two wing-bars and fringed tertials and pale primary tips. We are left with Greenish or Arctic. The main features to check are in the face, and the thick supercilium behind the eye, which meets above the bill, should take you to this being a Greenish Warbler.
KEY FEATURES Greenish upperparts, greyish underparts Prominent and long supercilium extends to forehead Obvious wing-bar High crown and pale lower mandible to bill ‘Open face’ with no dark eyestripe