At 10:49 AM 96.10.30 +0800, wrote:
>Llew Rintoul wrote :
>
>Green feathers (with the exception of the Turaco) are due to yellow pigment
>AND refraction of blue light (the same reason why the sky appears blue).
>Thus a blue budgerigar would be green if it had the yellow pigment.
>Microscopic air-cells in the barbs of the feather are the site where
>refraction occurs. Some feather diseases will upset these air-cells and
>disrupt the refractive process (causing green feathers to appear yellow and
>blue feathers to appear white).
I find this topic interesting. King et al (Birds of Southeast Asia) state
that the plumage of the Green Magpie (Cissa sp.) "changes to pale blue in
captivity, in ill health and after death." Why might this be? Also Dusky
Green Fulvetta (Alcippe cinerea) becomes dusky in the museum drawer (I
hear) but is much brighter yellowish in life. (Sorry I'm not up on Aus
birds yet)
>
>Some birds like the Turaco produce genus or species specific pigments.
>Also many parrots have feather pigments which fluoresce under UV light.
>
>The following reference is very useful even though it is focussed on poultry:
>
>Lucas and Stettenheim (1972) Avian Anatomy - Integument, Parts I and II,
>Agricultural Handbook 362, Agricultural Research Service, USDA.
I'd be very interested to know what is known about the UV reflectance of
bird plumages. This could be important in understanding the taxonomic
status of allopatric forms - for example, the various island sspp of
Philippine Hanging Parrot but also Pittas etc etc. It might also tell us
how likely we are to be visible to the birds in ways in which we are
unaware. Perhaps aviculturists know more about this than birders.
I am unlikely to be able to get my hands on this reference easily but would
it answer many of my questions anyway?
Des Allen
Machida Shi, Japan
e-mail:
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