A ‘Copper’ Southern Double-Collared Sunbird

This bird was seen on 14 May 2013 in the Fernkloof Nature Reserve in Hermanus by Craig Adam. He has already loaded it up to the Birds with Odd Plumage Virtual Museum, where you can see the full details of this record: http://vmus.adu.org.za/?vm=BOP-81. It is a Southern Double-collared Sunbird which has a copper instead of a green irridescence. One of the most remarkable photos in this Virtual Museum! Thanks, Adam, for this fascinating contribution.

The Birds with Odd Plumage Virtual Museum is slowly building up a remarkable collection of records of oddities of colouration of feathers and deformities of beaks, legs, etc. Whether it will ever deliver any “science” remains to be seen, but if we can accumulate enough of these records we might start to find some interesting patterns.

There are lots and lots of Virtual Museums. Please have a browse around the website at http://vmus.adu.org.za/ — please upload your birds, butterflies, scorpions, … there are “how to do it” instructions on the website.

Found this reply by Doug Harebottle on the net: Looks like copper iridescence to me.
The basics of iridescence in sunbirds (like in hummingbirds) is caused by structural properties in the feathers and the way that light reacts with/over these microscopic structures. These structures (which comprise layers of air-bubbles on the feather surface) vary in thickness and thus absorb and reflect different wavelengths of light. Basically acts like a prism. This is why we then see different ‘shiny’ colours on the birds. So what we see is actually the result of light refraction from feather structure and not due to pigmentation!. There will be pigment but this will usually be a single darkish colour (brown or black). (This is a basic and hopefully easy to understand version, it gets quite technical when you examine things in more detail and for different species).
So perhaps this bird has a different structural layer of ‘air bubbles’ which refracts a ‘copper colour’ and not the usual green? All in all though quite phenomenal.

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