Common Chiffchaff
Phylloscopus collybita
The common chiffchaff is a small, dumpy, 10–12 centimetres (3.9–4.7 inches) long leaf warbler. The male weighs 7–8 grammes (0.28–0.31 oz), and the female 6–7 grammes (0.25–0.28 oz). The spring adult of the western nominate subspecies P. c. collybita has brown-washed dull green upperparts, off-white underparts becoming yellowish on the flanks, and a short whitish supercilium. It has dark legs, a fine dark bill, and short primary projection (extension of the flight feathers beyond the folded wing).
ID text from Wikipedia, CC BY-SA 4.0
Yellow-browed Warbler
Phylloscopus inornatus
This is one of the smaller Old World warblers, at 9.5–11 cm long and weighing 4–9 g distinctly smaller than a chiffchaff but slightly larger than Pallas's leaf warbler. Like many other leaf warblers, it has overall greenish upperparts and white underparts. It also has prominent double wing bars formed by yellowish-white tips to the wing covert feathers (a long bar on the greater coverts and a short bar on the median coverts), yellow-margined tertial feathers, and long yellow supercilium. Some individuals also have a faint paler green central crown stripe though many do not show this.
ID text from Wikipedia, CC BY-SA 4.0
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