Re Jim / Stephen exchange:
Look at museum bird skins under ultraviolet light and a number of species
show feather colours that can't be seen in daylight, eg glowing yellows. We
bird vets have been surgically sexing monomorphic birds for years, eg
lorikeets, conures, macaws etc but obviously the birds know the gender of
the other birds without having to resort to laparoscope or DNA sexing. At
one stage the colour differences under UV, which birds would be able to
discern because of their wider visual spectrum was hailed as their possible
cue to gender differences but, alas, the glowing colours under UV didn't
correlate with gender, only species. The birds have still got us beat.
The postings on the diving penguins breathing were very interesting. Would
Steve or Shane or anyone comment on whether the one way flow
counter-current system of oxygen exchange in the avian lung would be
advantageous cf with mammalian lung structure at depths? My guess it that
while it is an advantageous at high altitudes to improve oxygen absorption
it doesn't make much difference at depths because the air is not flowing
through the lungs. How do mammalian dive depths/times records compare with
penguins?
Pat Macwhirter BVSc (Hons), MA, FACVSc
Registered Specialist in Bird Medicine
Highbury Veterinary Clinic
128 Highbury Road, BURWOOD, VICTORIA, AUSTRALIA
Ph: (03) 9808 9011 Fax: (03) 9888 7134
>> Some plumage patterns and colours reflect ultra-violet light which can only
>> be detected by the human eye when viewed under an ultra-violet light
>> source.
>
>You lost me here. Since humans can't preceive UV, how could we view UV
>under a UV source?
>
> If birds are more sensitive than humans at detecting reflected
>> wavelengths at the UV end of the light spectrum, then maybe evolution
>> favours colours and patterns that reflect UV light.
>>
>This would be fascinating. There are a few studies that suggest that this
>is the case (e.g. on Bluethroats in europe).
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