Common chiffchaff (Phylloscopus collybita)

The common chiffchaff, or simply the chiffchaff, is a common and widespread leaf warbler which breeds in open woodlands throughout northern and temperate Europe and Asia. Wikipedia 


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 Canon 6D, Canon EF 100-400L ƒ4.5-5.6 IS USM, at 340mm, ISO1000, 1/500, ƒ/5.6