next message in archive
next message in thread
previous message in archive
Index of Subjects
All: Gareth Harding took me over this afternoon to see the strangely colored finch or sparrow visiting his feeder with a flock of House Sparrows. It turned out, as expected, to be a House Sparrow, probably a female, that appears a lovely buff colour all over, with yellow bill and legs. This plumage shows why I have been preaching lately to birding friends on the inadequacy of terms like "albino" or "leucistic" even qualified as "partially" in talking about plumages of birds. It is more accurate and flexible to use terms for the absence of particular pigments. This House Sparrow is "aneumelanistic" in lacking all black pigment (eumelanins) in feathers and in the keratin of legs and bill (made of same substances as feathers). It does not lack the brown pigments (phaeomelanins)found throughout much of its plumage. However, these brown areas don't vary much in tone because the brown areas in normal sparrows are also variably dosed with black pigments. There have been some buff-coloured crows in recent years that seem to have the same (genetic?) defect. An all white crow lacking both black and brown pigments is "amelanistic" (i.e., both "apheaomelanistic" and "aneumelanistic"). One with white patches is "partially amelanistic." One with gray, rather than black plumage (one in Cambridge, Kings Co., at present, would be "hypomelanisic"; a gray bird (e.g. catbird?) that is black, rather than gray, is "hypermelanistic." None is "albino" or "leucistic." This approach helps when other pigments are lacking in birds that aren't all black. There have been male N. Cardinals that have pinkish or reddish faces instead of black faces. They're not white, and therefore not "albino" or "leucistic" to even "partial", but they are aneumelanistic - same as this House Sparrow. If you see an all white cardinal (with dark eyes), it is technically "arhodoxanthic" (lacking red pigments, although other red pigments might be involved), yet may still have a black face (if it doesn't, it's also amelanistic. Hope this helps and is not too confusing. I will put a photo of this bird on the NS-RBA photo site. Cheers, Ian
next message in archive
next message in thread
previous message in archive
Index of Subjects