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House Finch Color and Dark Eyed Juncos (1 Viewer)
- Thread starter karenw
- Start date
From another current thread on albino/leukistic birds, I can offer the following article that explains bird coloration extremely well. Katy Penland posted the article originally. If it's more than you want to wade through - red coloring in birds is derived from what they eat and deposited in the feathers. Barbara
Bolsa Chica's White Willet
By Charles T. Collins
"Western Tanager"
(Los Angeles Audubon Society newsletter)
November/December 2002, Vol. 69, No. 1
One of the most attractive qualities of birds is their bright and varied coloration. I doubt that there would be as many birdwatchers if birds were all drab "little brown jobs." The colorful appearance of birds is achieved by a variety of pigments being deposited in the skin and growing feathers.
The two commonest types of pigments are the melanins and carotenoids. The melanins include eumelanin which is responsible for the darker black and gray colors, while phaeomelanin is responsible for some of the lighter browns and tans and erythromelanin the richer chestnut-red colors. Melanins are synthesized by the birds and deposited as granules in the skin and feathers.
The carotenoid pigments include carotenes (red-orange), xanthophylls (yellow and orange), and carotenoids acids (reds). They are softer, non-granular, compounds which give birds their many shades of pink, red, orange and yellow. They produce some of the most intense colors such as those found in Scarlet Ibises and tropical tanagers and also the faint rosy blushes of the breeding season Elegant Terns and Ross's Gulls. These pigments for the most part cannot be synthesized by birds and must be obtained from plant or animal material in their diet and then deposited, often chemically unaltered, in feathers and soft parts.
In addition to pigment colors the physical phenomenon of light scattering is responsible for blue in feathers and skin as well as white or albinistic feathers. The highly metallic iridescent colors of many hummingbirds are caused by interference phenomena, as is also true in an oil film on water, but they also depend, in part, on underlaying melanin pigment layers.
Many of us have at one time or another seen a bird with abnormal coloration, particularly albino or partially albino birds. However, it is often more complex than a simple presence or absence of pigments. In June and July 2002 what appeared to be a white or largely white Willet was seen and photographed at the Bolsa Chica Ecological Reserve. Analysis of this bird is a good starting point for categorizing the several types of plumage abnormalities which occur in birds. This bird, as shown in the accompanying photos, was not a true albino, which requires a complete loss of pigment in both feathers and soft parts. Where there is a loss of pigmentation in the feathers but not the soft parts it is considered leucism. The spectacular photo of a white hummingbird with dark eyes and bill featured in the July-August 1994 "Western Tanager" would thus be a prime example of complete leucism. The term partial leucism would be used when there is only a partial to nearly complete loss of pigments from the plumage with white feathers occurring symmetrically or non-symmetrically over various parts of the body. Most people would simply call these partial albinos.
Less commonly encountered is melanic leucism where only the melanic pigments are lost and carotenoid pigments remain. An example of this is a specimen of a nearly all white Yellow-headed Blackbird in the Cal State University, Long Beach collection which lacks all of the black coloration but retains some of the yellow in the head region. It would certainly have been a spectacular bird to see in the field! Carotenoid leucism would be the opposite, where the carotenoid pigments are lacking but the melanins remain. A Yellow-rumped Warbler lacking the yellow throat, pectoral spots and rump but otherwise normally colored would be an example of this. Both of these cases refer to situations where these two types of pigments occur in different parts of the plumage.
Yet another category of abnormalities is called schizochroism. It involves situations where one pigment overlays another in the same feather. Melanic schizochroism occurs when there is a loss of the phaeomelanins (the browns) resulting in a more uniformly gray bird, or the loss of the eumelanins (the dark browns or blacks) resulting in an all tan or "fawn" colored bird. Melano-carotenoid schizochroism would describe the loss of one or the other of these two types of pigments where they normally are present in the same area. I have seen a specimen of a Red-winged Blackbird where the absence of some of the black pigment showed the red (which should be confined to the epaulets) to be much more widespread but normally masked in other areas by the denser melanins.
Carotenism describes several abnormalities involving the carotenoid pigments. These include changes in the distribution or amount of these pigments present as well as the shift from red to yellow often seen in our local House Finches. Extreme cases of all yellow birds, probably due to melano-carotenoid schizochroism, is found in some cage birds, particularly parrots, which are referred to as 'leutinos' by aviculturists.
Melanism is due to an excess of the eumelanins resulting in abnormally dark plumage as is occasionally seen in 'dark morph' Red-tailed Hawks and jaegers. An extreme case of this would be an all black bird which normally would have shown other colors as well.
Now, back to the white Willet of Bolsa Chica. The presence of some melanin pigments on the tip of the bill and in the wing feathers (partially delimiting the characteristic wing stripe of Willets) rules out this being a true albino. Partial leucism would probably adequately describe the condition in this bird. However, examination of the color photographs of this bird show some yellowish color to the base of the bill and upper legs, which would normally be obscured by overlaying melanin pigments. Thus this bird also exhibits a degree of melano-carotenoid schizochroism as well.
All of these different categories of plumage abnormalities may seem like splitting hairs (splitting feathers?); we could just continue to call them partial albinos or dark phase birds and be done with it. However, being aware of the actual basis for the diverse colors and color patterns, as well as the several kinds of abnormalities we may encounter, should serve to sharpen our observational skills and our overall enjoyment of birds and birding.
In writing this I have relied heavily on the chapter on 'Genetics' by P.A. Buckley in the book 'Diseases of Cage and Aviary Birds' by M.L. Petrak. I am indebted to Mike Bowles for the use of his superb photos of Bolsa Chica's white Willet which prompted this whole article.
********
Dr. Collins is an emeritus professor in the Department of Biological Sciences at California State University, Long Beach, where he continues to teach classes in Ornithology and Behavioral Ecology. His primary research interests are the biology of swifts, Island Scrub Jays and coastal breeding terns and skimmers.
Bolsa Chica's White Willet
By Charles T. Collins
"Western Tanager"
(Los Angeles Audubon Society newsletter)
November/December 2002, Vol. 69, No. 1
One of the most attractive qualities of birds is their bright and varied coloration. I doubt that there would be as many birdwatchers if birds were all drab "little brown jobs." The colorful appearance of birds is achieved by a variety of pigments being deposited in the skin and growing feathers.
The two commonest types of pigments are the melanins and carotenoids. The melanins include eumelanin which is responsible for the darker black and gray colors, while phaeomelanin is responsible for some of the lighter browns and tans and erythromelanin the richer chestnut-red colors. Melanins are synthesized by the birds and deposited as granules in the skin and feathers.
The carotenoid pigments include carotenes (red-orange), xanthophylls (yellow and orange), and carotenoids acids (reds). They are softer, non-granular, compounds which give birds their many shades of pink, red, orange and yellow. They produce some of the most intense colors such as those found in Scarlet Ibises and tropical tanagers and also the faint rosy blushes of the breeding season Elegant Terns and Ross's Gulls. These pigments for the most part cannot be synthesized by birds and must be obtained from plant or animal material in their diet and then deposited, often chemically unaltered, in feathers and soft parts.
In addition to pigment colors the physical phenomenon of light scattering is responsible for blue in feathers and skin as well as white or albinistic feathers. The highly metallic iridescent colors of many hummingbirds are caused by interference phenomena, as is also true in an oil film on water, but they also depend, in part, on underlaying melanin pigment layers.
Many of us have at one time or another seen a bird with abnormal coloration, particularly albino or partially albino birds. However, it is often more complex than a simple presence or absence of pigments. In June and July 2002 what appeared to be a white or largely white Willet was seen and photographed at the Bolsa Chica Ecological Reserve. Analysis of this bird is a good starting point for categorizing the several types of plumage abnormalities which occur in birds. This bird, as shown in the accompanying photos, was not a true albino, which requires a complete loss of pigment in both feathers and soft parts. Where there is a loss of pigmentation in the feathers but not the soft parts it is considered leucism. The spectacular photo of a white hummingbird with dark eyes and bill featured in the July-August 1994 "Western Tanager" would thus be a prime example of complete leucism. The term partial leucism would be used when there is only a partial to nearly complete loss of pigments from the plumage with white feathers occurring symmetrically or non-symmetrically over various parts of the body. Most people would simply call these partial albinos.
Less commonly encountered is melanic leucism where only the melanic pigments are lost and carotenoid pigments remain. An example of this is a specimen of a nearly all white Yellow-headed Blackbird in the Cal State University, Long Beach collection which lacks all of the black coloration but retains some of the yellow in the head region. It would certainly have been a spectacular bird to see in the field! Carotenoid leucism would be the opposite, where the carotenoid pigments are lacking but the melanins remain. A Yellow-rumped Warbler lacking the yellow throat, pectoral spots and rump but otherwise normally colored would be an example of this. Both of these cases refer to situations where these two types of pigments occur in different parts of the plumage.
Yet another category of abnormalities is called schizochroism. It involves situations where one pigment overlays another in the same feather. Melanic schizochroism occurs when there is a loss of the phaeomelanins (the browns) resulting in a more uniformly gray bird, or the loss of the eumelanins (the dark browns or blacks) resulting in an all tan or "fawn" colored bird. Melano-carotenoid schizochroism would describe the loss of one or the other of these two types of pigments where they normally are present in the same area. I have seen a specimen of a Red-winged Blackbird where the absence of some of the black pigment showed the red (which should be confined to the epaulets) to be much more widespread but normally masked in other areas by the denser melanins.
Carotenism describes several abnormalities involving the carotenoid pigments. These include changes in the distribution or amount of these pigments present as well as the shift from red to yellow often seen in our local House Finches. Extreme cases of all yellow birds, probably due to melano-carotenoid schizochroism, is found in some cage birds, particularly parrots, which are referred to as 'leutinos' by aviculturists.
Melanism is due to an excess of the eumelanins resulting in abnormally dark plumage as is occasionally seen in 'dark morph' Red-tailed Hawks and jaegers. An extreme case of this would be an all black bird which normally would have shown other colors as well.
Now, back to the white Willet of Bolsa Chica. The presence of some melanin pigments on the tip of the bill and in the wing feathers (partially delimiting the characteristic wing stripe of Willets) rules out this being a true albino. Partial leucism would probably adequately describe the condition in this bird. However, examination of the color photographs of this bird show some yellowish color to the base of the bill and upper legs, which would normally be obscured by overlaying melanin pigments. Thus this bird also exhibits a degree of melano-carotenoid schizochroism as well.
All of these different categories of plumage abnormalities may seem like splitting hairs (splitting feathers?); we could just continue to call them partial albinos or dark phase birds and be done with it. However, being aware of the actual basis for the diverse colors and color patterns, as well as the several kinds of abnormalities we may encounter, should serve to sharpen our observational skills and our overall enjoyment of birds and birding.
In writing this I have relied heavily on the chapter on 'Genetics' by P.A. Buckley in the book 'Diseases of Cage and Aviary Birds' by M.L. Petrak. I am indebted to Mike Bowles for the use of his superb photos of Bolsa Chica's white Willet which prompted this whole article.
********
Dr. Collins is an emeritus professor in the Department of Biological Sciences at California State University, Long Beach, where he continues to teach classes in Ornithology and Behavioral Ecology. His primary research interests are the biology of swifts, Island Scrub Jays and coastal breeding terns and skimmers.
Katy Penland
Well-known member
Here's what the Cornell U's site says about the male House Finch:
"Male House Finches display extreme color variation, ranging from pale yellow to bright red. The depth of red coloring in each male depends on the amount of carotenoid pigments in the bird’s food sources during the molting period."
I've had yellow, pink, neon orange, red and fuscia-colored male House Finches here. It's quite startling to see the range of colors.
Like KC's birds, our Dark-eyed Juncos here love the millet (white and red) as well as sunflower seeds, and any pieces of suet cake that fall to the ground.
"Male House Finches display extreme color variation, ranging from pale yellow to bright red. The depth of red coloring in each male depends on the amount of carotenoid pigments in the bird’s food sources during the molting period."
I've had yellow, pink, neon orange, red and fuscia-colored male House Finches here. It's quite startling to see the range of colors.
Like KC's birds, our Dark-eyed Juncos here love the millet (white and red) as well as sunflower seeds, and any pieces of suet cake that fall to the ground.
Just a comment that millet isn't native to North America, so Dark -eyed Juncos better be eating something else before they arrive at our feeders. Mine eat everything if it's small enough. They really like to clean up the niger seed even if I have millet out. Birds are flexible in diet. We have a lost female Summer Tanager (just a bit north of its range) that is now eating suet & Highbush Cranberries. She will now try to overwinter. Two or three species of birds which should have flown south to warmer climes show up almost every year. They often make it through our snowy, -30 Celsius winters if the food supply is constant & sufficient for their needs.
Katy Penland
Well-known member
Hal said:
Yikes, I didn't know millet wasn't native to NA! It's a big component of every commercial bird seed mix! Nobody eats the milo that also comes in these mixes (at least not that I've been able to determine). Possibly some of scrub and Steller's jays do but only occasionally. But the siskins, juncos, the smaller sparrows, like chipping, really go for the millet, especially the "gourmet mixes" that have grass seed mixed in with the red and white millet.
Hal, what do you offer your juncos besides niger? Sunflower hearts? I'd always much rather give them what they *should* be eating vs. what's more convenient for me to set out.
Hi Katy,
Don't worry about it! Millet is a fine choice as food for Juncos. If the millet runs out they go for the niger seed fallout and will also turn to the grass seed. They occasionally get sunflower seed hearts and when I have overwintering insectivores they get a few more mealworms. I gathered a few pounds of Amaranth seed this fall & most of the ground feeding species seem to like it a lot. No commercial sources that I've been able to locate though. The seed is so small getting a feeder that will hold it is a problem. Mostly I've been scattering it on a piece of plywood placed on the ground.
I put out a bit of everything (suet mixes, various seeds, fruits, & Mealworms) & let the them pick and choose. If something isn't popular I just reduce the amount. I've had individuals show up later that just loved seeds nothing else would touch.
I keep clean, disinfected & filled duplicates of all my feeders (except the Table feeders) in the house ready to go. Nothing puts you off than having to go out in a blizzard at -40C (also -40F)to fill a dozen feeders. This way the birds are safer & it only takes a few minutes to ensure everything is full. I can then take my time cleaning & filling them.
Sounds to me like you're doing it right, carry on & keep feeding them.
Don't worry about it! Millet is a fine choice as food for Juncos. If the millet runs out they go for the niger seed fallout and will also turn to the grass seed. They occasionally get sunflower seed hearts and when I have overwintering insectivores they get a few more mealworms. I gathered a few pounds of Amaranth seed this fall & most of the ground feeding species seem to like it a lot. No commercial sources that I've been able to locate though. The seed is so small getting a feeder that will hold it is a problem. Mostly I've been scattering it on a piece of plywood placed on the ground.
I put out a bit of everything (suet mixes, various seeds, fruits, & Mealworms) & let the them pick and choose. If something isn't popular I just reduce the amount. I've had individuals show up later that just loved seeds nothing else would touch.
I keep clean, disinfected & filled duplicates of all my feeders (except the Table feeders) in the house ready to go. Nothing puts you off than having to go out in a blizzard at -40C (also -40F)to fill a dozen feeders. This way the birds are safer & it only takes a few minutes to ensure everything is full. I can then take my time cleaning & filling them.
Sounds to me like you're doing it right, carry on & keep feeding them.
