American Goldfinch Plumage Anomaly
Molting, the replacement of all or some of a bird’s feathers, occurs in response to a mixture of hormonal changes brought about by seasonal changes. This process serves to replace worn feathers (they cannot repair themselves) and can play a part in seasonal camouflage as well as attracting a mate.
All of our small songbirds have a complete molt, replacing all of their feathers in late summer. In addition, many species have a partial molt (replacing body feathers but not wing or tail feathers) in the spring.
According to David Sibley, American Goldfinches begin to molt all of their (alternate/breeding plumage) feathers in September, with the males replacing their brilliant gold feathers with much duller feathers by November. Come spring and the breeding season, male goldfinches replace their dull (basic/non-breeding) body feathers (but not the wing or tail feathers) with new, bright feathers.
Imagine my surprise when I spied a brilliantly colored American Goldfinch at my feeder this week. According to ornithologist George Clark, it’s usually March before one starts to see an American Goldfinch in breeding plumage. One can only wonder what prevented this individual from molting its breeding plumage in the fall. (Photo: male American Goldfinch, winter plumage; inset – male American Goldfinch in breeding plumage in January)
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Snowy Egrets Becoming More Colorful
For those New Englanders fortunate enough to live on the coast, Snowy Egrets are a welcome sight this time of year as they return from their wintering grounds to breed. Like most herons and egrets, they acquire plumes – long, wispy feathers – on their back, neck and head during the breeding season. (These plumes were highly sought after by the women’s hat trade in the late 1800’s and early 1900’s. They were valued at $32 per ounce, twice the price of gold at the time. Eventually laws were passed to protect the birds.)
Something slightly more subtle but equally as dramatic as ornate plumage highlights the appearance of these birds in the breeding season and that is a change in bill and feet coloration. Different species of herons and egrets exhibit different color changes. Snowy Egrets’ greenish-yellow feet turn a much richer orange-yellow hue during the breeding season, and the patch of bare skin at the base of their bill (lore) changes from a yellowish color to a pinkish/reddish color, only seen at this time of year.
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Colorful Breeding Season Changes in Heron Family
The changes birds experience in their appearance during the breeding season sometimes include a partial molt, resulting in a more colorful or ornate plumage in the spring. In addition, some species, such as those in the Heron family (herons, egrets and bitterns), undergo changes in the color of their bills, legs, feet and lores (area between eye and bill) during their brief period of courtship. As an example, Snowy Egrets (pictured), during most of the year, have featherless yellow patches of skin, or lores, at the base of their bill and greenish-yellow feet, but in the spring, their lores turn red and their feet a bright yellow-orange.
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