Mute Swan, (Cygnus olor), male bird, Regents Park, London, United Kingdom

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The black knob at the base of the male Mute Swan's bill swells during the breeding season and becomes noticeably larger than the female's. The rest of the year the difference between the sexes is not obvious.

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Size: 3558px × 5192px
Location: Regents Park, London, United Kingdom
Photo credit: © Dominic Robinson / Alamy / Afripics
License: Licensed
Model Released: No

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