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Philip,
There is no limit to the number of
questions!
I am really interested to understand why one sex
would have a different eye colour to the other and because yellow is an eye
colour of some nocturnal birds (owls, frogmouths, stone-curlews), is it an
adaptation to nocturnal feeding (or other activity). If so why doesn't the
male also possess a yellow eye as he also forages at night? The yellow eye
would aid in the recognition of the sexes in a species that doesn't usually
vocalize and is not otherwise dimorphic, other than on size.
The only other example that I know of sexually
differeing eye colours is the closely related Saddle-billed Stork of Africa, in
which the female also has a yellow iris and the male a brown iris. The
Black-necked Stork was placed in the same genus as the Saddle-billed on the
basis of the sexually differing eye colours and other morphological and
behavioural similarities.
Any ideas on the blue, green and purple sheen on
the black plumage of the stork? Presumably it would reflect the sun and
like white feathers would assist in thermoregulation.
Regards
Greg
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