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 Post subject: Leucistic Birds
Unread postPosted: Mon May 16, 2005 9:32 am 
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ImageImage
ps: I know it is a bulbul
Pics taken along H4-2 near Lower Sabie.

(These pics are taken off a video clip - this world famous wildlife photographer could not focus on the bird in time :oops:)

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Unread postPosted: Mon May 16, 2005 10:24 am 
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White pigmentation is caused by a recessive gene, it is called amelanistic.

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Unread postPosted: Mon May 16, 2005 10:33 am 
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wildtuinman wrote:
Melanism, is actually dark collaration. I am looking for the correct word of partial albinism.

Partial albinism only affect certain parts of the body.


I believe that is called leucistic?

Found some info re albinisme versus leucism here


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Unread postPosted: Mon May 16, 2005 10:33 am 
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wildtuinman wrote:
White pigmentation is caused by a recessive gene, it is called amelanistic.
Excuse me if I am being dom here but is white pigmentation diferent from albinism? If so, are both hereditary? Could this bird have 'relatives' of the same colour?

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Unread postPosted: Mon May 16, 2005 10:39 am 
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Jose wrote:
I believe that is called leucistic?

Found some info re albinisme versus leucism here


That is the word! Here is a 50-50 article.

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Unread postPosted: Mon May 16, 2005 10:44 am 
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Thanks for all the info you two! Will send in the clip to 50/50 and keep you posted re their response etc.

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Unread postPosted: Mon May 16, 2005 11:00 am 
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I think it's called leucism. Here is some info on bird coloration I found on the net. The birds mentioned is not SA birds but it may help explaining things:

...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

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.

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Last edited by francoisd on Mon May 16, 2005 11:08 am, edited 1 time in total.

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