Philip - I won’t go on and on with the graphics but that group photo from Werribee in November shows a resting flock of at least 54 avocets and 26 banded stilts (no black-winged). I counted them by the paintbrush method as shown below, putting together 3 snaps to get the whole flock in with some detail that could be enlarged. In response to something Con mentioned this would be a good method of counting flocks for survey purposes. I remember seeing a high resolution shot Barry Baker used to count seabirds on a sub-antarctic island, and I’m sure the same thing is done for waterbird surveys elsewhere in the country.
Now the same photo examined when zoomed in on (not this version though) clearly shows varying avocet head colours. The juvenile birds (just a small number – indicated by a greyish wash on the white plumage) definitely have paler heads compared to adjacent adults.)
In view of their preference for salty conditions, I wouldn’t expect any bandeds here. However I had been predicting the avocets were due to arrive. I remember the single one we had at Kellys a few years ago - arriving inconveniently just after the cut-off for Steve Wilson’s book.
From: Philip Veerman [
Sent: Wednesday, 2 January 2013 2:02 PM
To:
Subject: [canberrabirds] Plumage colours
I had not particularly thought about it but some other questions arise and I don't know the answers. Are all the Avocets coloured the same? It appears from the photo that they are not. However I suspect that they are, and the differences are due to other things. Is the chestnut (or whatever) colour, unvaried, wherever it occurs. It appears from the photo that the backs of the necks are often darker than the tops of the head. However I suspect that is not because of colour of the feathers but because we are seeing through different numbers of layers of feathers and / or the angle of the light . If the feathers are fluffed out, we may be seeing only one layer but if sleeked down or flat against a solid object we are seeing multiple layers of the same colour which will make it appear darker or maybe browner. Of course also as a water bird, presence of water may darken the appearance.
By the way, did we all pick the Banded Stilts in the photo?
-----Original Message-----
From: Geoffrey Dabb
Sent: Wednesday, 2 January 2013 11:03 AM
To: m("canberrabirds.org.au","canberrabirds");">
Subject: [canberrabirds] Plumage colours
Thanks for opening up a fascinating subject, Bill, but I must disagree.
The 'Naturalist's Colour Guide', first part published in 1974, was intended 'to give ornithologists and other naturalists an accurate and handily available tool to use in describing the colours of birds and other animals'. It was based on spectrophotometry analysis of actual plumages. Comparisons were made in the laboratory under precise specifications as to uniform lighting. It used a code written in terms of hue, value (light/dark) and chroma (saturation). Fine divisions on those aspects were expressed in decimals. Colour 240, which came out in Part III after a long discussion about the confused rufescence issue in Part II, has a code 3.6 YR 4.5/6.7. For practical purposes, this seems precise enough.
A selection of common colours was then published in the guide. Printing limitations would have been an issue, but great care was taken to keep the printed product as useful as possible. HANZAB was prepared using the guide against actual plumages in specified lighting, It gave 'dark 240' as the best match for the avocet head. The match might be, in a sense, 'approximate', but I think it can be taken as a scientifically sound assessment, and any degree of 'approximation' is negligible compared (my main point) to the enormous variation in apparent colour due to variable light in the field - or in photographs.
Now we come to the separate question of names for colours, which was what you raised in your first message. There will be no agreement on this, unless an agreed nomenclature (take the one in the guide if you wish) is used. 'Kingfisher Rufous' was just made up. The important thing is 'Colour 240', which is given by HANZAB for the avocet head. Now HANZAB itself did not adopt the Guide NAMES: 'these were used by Smithe only to convey a sense of familiarity'. 'One man's sepia is another man's fuscous, and so on ... Names of colours given in the text are simple (eg dark brown) so that readers unfamiliar with complex colour descriptions(eg burnt umber with a trace of cinnamon) will not be misled'. I would agree on that basis 'chestnut' is the most general of approximations, but not 'dark 240'.
Since publication of the Colour Guide the digitising of colours has introduced a whole new element. The radiant light (if that is the _expression_) from your monitor, and the possibility of variable colour setting, are as serious a source of distortion as the limitations of the printing process, but that is another matter. I couldn’t agree more about the wonderful effect we are getting at the moment with that early morning light. Here is my impression of ‘burnished avocets’ – using the ‘colour stretch’ button on one of my graphics programs.
.
To: m("canberrabirds.org.au","canberrabirds");">
Subject: Colour on an avocet
From: Bill & Raelene <m("grapevine.com.au","graham.br63");">>
Date: Tue, 01 Jan 2013 17:25:12 +1100
Thank you for the colour codings Geoffrey. HANZAB's chestnut and 'dark 240' in the colour guide and 'Kingfisher Rufous' are approximations. Red- necked in the avocet does not mean the primary colour red but a variation that is somewhere in between a secondary(orange) and tertiary colour (brown). Rufous means reddish and there will be variations of rufous depending on light. The heads and necks of the Forde avocets, with the early morning sunlight glowed with that golden burnish. Though I saw them briefly, the impression was indelible.
Bill
-----Original Message-----
From: Bill & Raelene [m("grapevine.com.au","graham.br63");">]
Sent: Tuesday, 1 January 2013 12:11 PM
To: m("canberrabirds.org.au","canberrabirds");">
Subject: [canberrabirds] avocets at Forde Pond.
What shade would you call that striking colour on the head and neck? chestnut, sienna, umber, light red, milk chocolate?
Bill Graham
