Sexing Blue Tits may be rather straight forward when it comes to typical individuals, but quite many are more difficult (especially 1cy/2cy) and some should be left undetermined. Do not use wing length. Always start with ageing.
Male (1cy) November. Note broad and dark marine blue side of neck as well as a deep blue crown. The dark eye-stripe is on average broader and more distinct (darker), but intermediates are frequently seen. [1ET81027]
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