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Evening Grosbeak Bills Changing Color

3-10-13 evening grosbeak female IMG_0734Breeding season changes in a bird’s physical appearance can involve more than a set of new feathers. The colors of birds’ feet, legs and bills can also change in different seasons. One transition most people are aware of is the European Starling’s bill which is black in winter and turns yellow as the breeding season approaches. Male and female Evening Grosbeaks also undergo a change in bill color, from bone-colored in the winter, to a greenish hue in the spring. Hormones are largely responsible for these pigmentation changes which often play a role in courtship behavior. Usually change in the color of the bill is most pronounced among birds which retain the same plumage color and pattern throughout the year, such as starlings and Evening Grosbeaks. (Photo-female Evening Grosbeak)

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8 responses

  1. Beautiful bird.

    March 10, 2014 at 12:58 pm

  2. Bill On The Hill...

    Hi Mary, Great profile shot on the female grosbeak. The eye & beak detail is spot on & the ruffed grouse impression in the snow was fabulous! Keep up the great work… BF

    March 10, 2014 at 1:03 pm

  3. Penny March

    Interesting about the beaks, but thought Starlings changed their plumage too…speckled in winter and glossy purple/black in summer.

    March 10, 2014 at 1:07 pm

    • Hi Penny,
      There are slight seasonal differences in their plumage, but only because of wear and tear…After starlings molt in late summer, most of their head and body feathers have whitish or buff spots at their tips. These light spots gradually wear away to produce the glossy black appearance of spring (although most birds retain at least a few of these spots).

      March 10, 2014 at 1:18 pm

  4. Dianne and Ed

    How MIRACULOUS is the natural world:-) Dianne

    March 10, 2014 at 1:08 pm

  5. Grady

    From feeder observations, it appears house finches become more purple as they enter the transition from winter to spring breeding season.

    March 10, 2014 at 3:14 pm

  6. I LOVE evening grosbeaks, especially the males. I call them “Space Men” because they look like they are wearing bright yellow and black spacesuits. Unfortunately, they are rarely seen in these parts anymore. I’ve read their numbers have declined 75%. 😦

    March 10, 2014 at 6:43 pm

  7. Trew Bennett

    Your post forwarded to me from ‘craignavie@aol.com Thank you

    March 10, 2014 at 10:34 pm

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