red-necked Swans

No, there is no such species as a Red-necked Swan, and no, they aren’t from rural hilltops in Appalachia — these are Trumpeter Swans that apparently have been feeding in water rich in iron salts which have become deposited in their white head and neck feathers.

trumpeter swans-

Although I was forced to shoot directly into the sun, which caused deep shadows on the birds, nevertheless the swans’ heads and necks are much darker than their bodies.

trumpeter swans-

Closer view shows up their rusty-colored heads and necks, with minor staining of their body behind the wings.

Way back in 1955, E.O. Hohn reported this discoloration of white feathers in a variety of waterfowl (e.g., Snow Geese, another all-white bird).  He was curious whether this was some aberrant pigmentation so he leached the feathers with a mild acid, which removed the color entirely.  He then tested the leaching solution for iron, which proved positive.

And there you have it — rusty-colored Trumpeter Swans marked by where they have been spending their winter in high iron-content water.

trumpeter swans-

You can see the rusty color better on the head of the bird who is preening, as the sun lights up its head.

NOTE added after posting:  Based on the amount of reddish-brown staining of neck feathers all the way down to the breast, I might speculate even further that these particular birds were feeding in deep, iron-rich waters, where they had to “tip-up” to feed (as shown below).

trumpeter swan tipping up

5 thoughts on “red-necked Swans

    • There has been some discussion of whether the rusty brown head indicates that the bird is still in its first year of life. If you google “juvenile trumpeter swan”, you’ll find dozens of photos of swans with brown heads — this might be the source of the confusion. But wildlife biologists point out that the natal (birth) plumage of swans is gray, which is gradually replaced by the next spring with the all-white plumage.

  1. Pingback: Photos I wish I had taken | Back Yard Biology

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