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bcintbird-pics Colour factors and moult - delete now if you have had enough of Grosbeaks M Lancaster Tue Feb 21 01:01:25 2012

OK - moult and 'red feathers'.

It is perfectly possible to have red, yellow, shades of red, shades of yellow, 
and feathers with red and yellow in them ALL as part of the same moult, OR, 
indeed, feathers without any of the said colours. Hence for example, black or 
grey feathers in the Pine Grosbeak.

Firstly, the red/yellow complex ( in most species of birds) is derived from 
eating foods containing precursors to aforesaid red/yellow complex.

Secondly, feathers are moulted feather tract by feather tract.

Thirdly, each tract is programmed to produce feathers of a certain type and 
colour.

Fourthly, growing feathers takes time.

So, even if a feather tract was supposed to 'turn' red, if the bird did not 
have access to precursors, or have a store in the body (see below (1))  
feathers could be of different colours and especially those that take weeks to 
grow, could even exhibit differences of shade or even absence (of colour) in 
the same feather.

Normally, apparently bizarre appearances would not occur of course - but it is 
possible.

Then, one has to consider sex (gender not act). Female Grosbeaks do not 
normally appear red (if at all?) so they are eating the same precursors as the 
males and not (I guess!!!!) having the same 'magic ingredient' as males (that 
produce red)  and only produce yellow (or shades thereof and occasionally 
reddish - 'bronze' is a term used  - see below (2)). 

That said, it is perfectly possible for a male to have yellow(ish) feathers in 
varying amounts and especially if it is a young male - indeed the common 
consensus is that first year (of LIFE) Pine Grosbeaks look like females yet in 
the second year (of LIFE) therefore 1/2 calendar and 2/3 calendar years they 
appear as 'males'. What is more, generally speaking the amount and intensity of 
'redness' does increase somewhat as male birds age ( and I have speculated this 
could occur with females also).

OK now for the difficult stuff :-), and another species (or species). For about 
25 years I was an aviculturalist  and associated with others who bred many 
different species of birds in captivity - I mainly confined myself to 
psittacines. However, by association and research and post mortem I learned a 
few things about 'colour fed' birds and indeed at one time I was breeding the 
ubiquitous House Finch. Colour has a major impact on the so called 'Red factor' 
Canaries which arose as the result of a hybridisation between the Canary 
(Serinus canaria - yes, from the Canary Islands) and the Red Siskin (Carduelis 
cucullata) from South America. Canaries without Red Siskin genes and without 
access to natural foods or manufactured 'red colourants' cannot produce red 
feathers - yellow, yes, because that process is part of the original Canary 
gene package. Hence, the average perception that Canaries are yellow - sorry 
folks, not wild ones.

House Finches kept in captivity also need access to natural foods or 'red 
colourants' before males will exhibit red feathers. NB females eating food or 
drinking water containing 'red colourants' do not have red feathers. It is 
perfectly possible to see House Finches in the wild with yellow feathers where 
red should be.  If my experience with captive House Finches is worth anything, 
these are probably birds in their second calendar year.

Now, nobody seems to know just how much (colour)-food or how much powder should 
be added to food or drink in order to facilitate a red appearance of Canaries. 
This must be provided before and during the period of moult.Too much colourant 
results in the appearance of what is termed 'burnt' birds which are a reddish 
bronze in colour ( see above 2). Such birds can and do produce red feathers in 
a succeeding moult (or moults ??) as the result of the 'red colourant' being 
stored in fat - post mortem shows birds with bright red fat (see 1 above). I 
doubt if this occurs in the wild.

So, given the right or wrong conditions almost anything can, and does happen - 
ain't nature wonderful?

For those who have not had enough of this subject, I suggest one 'Googles' 
Carophyll Red - there is also a Carophyll Yellow. Also 'Google' carotenoids - 
Birds of North America offers a short discourse pertinent to Pine Grosbeaks.

Barry

M B Lancaster,
Currently - Tenerife, Islas Canarias
  ----- Original Message ----- 
  From: Rick Howie 
  To: [EMAIL PROTECTED] 
  Sent: Tuesday, February 21, 2012 1:07 AM
  Subject: RE: bcintbird-pics grosbeak identification


  High again Phil. It is a curious phenomenon in that by the time this bird had 
moulted in all of those red feathers, the rump feathering should have followed 
suit as the molt is normally complete. It appears as if there can be aberrant 
individuals whereby some feathers forgot to fly away and make room for the new 
inbound ones. A constant reminder that nature retains the right to variation 
for whatever reasons and purposes. 'tis perhaps only humans that make rules and 
then expect everybody and everything to obey them.

   

  Perhaps Barry can enucleate the reason for such variation which we shall 
entitle " Lancaster's Molt Parable." 

   

  Rick Howie  

   

  From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Phil Ranson
  Sent: February-20-12 1:54 PM
  To: [EMAIL PROTECTED]
  Subject: Re: bcintbird-pics grosbeak identification

   

  I haven't been following the particulars of this discussion, but thought I'd 
throw in a recently taken photo by Rod Sargent at Baker Creek west of Quesnel. 
He was intrigued by the mustard rump on an otherwise typical adult male 
plumage. 

   

  Phil Ranson

  Williams Lake

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