I cannot answer to the second question posed by Tony Lawson's friend:
<What is it about WA that 'fades' birds?! eg Yellow-tailed to White-tailed
Black-cockies; Eastern Yellow to Western Yellow and White-breasted Robins. >
Firstly, the question is not posed in a way it can be answered. It is a
question about the evolution of colour in certain bird taxa, not about WA.
Really, the question is compound: "why have some species pairs/groups of birds
evolved yellow forms and white forms in different geographical areas?" and "is
the same reason(s) involved for robins and cockatoos?". Answers to these will
require answers to "how did each species group evolve?" and "what is the
evolutionary function of the colours in each group?". Answer these 4 questions
and it should be clear whether "WA" is a causal factor in these two groups or
whether it is coincidental.
Secondly, the question is based on a premise that is probably false. There are
plenty of brightly coloured birds and many other colours in WA, as Frank has
noted, and plenty of faded birds in the east. There is no answer to the
question, "why is the sky yellow?".
Tempting as it might be to think so, there is probably nothing in the water in
WA that makes things dull :-)
The first question <why are NZ birds generally less brightly coloured than east
coast Australian ones?> presents similar problems. However, in this case I
suggest that the premise is based on a biased view that Australia has brighter
coloured birds than NZ does. It does, but it also has duller-coloured ones like
Brown Gerygone, Brown Honeyeater, Large-billed Scrubwren, Jacky Winter,
etc. These all have different evolutionary reasons for being dull in colour. NZ
simply has fewer bright bird species, fewer dull bird species, fewer bird
species, less evolutionary radiation of birds, less variety. Which begs the
question, why....
From: Frank O'Connor <>
To:
Sent: Tuesday, 26 July 2011 4:40 PM
Subject: couple of questions
Tony Lawson posed the question :
2. What is it about WA that 'fades' birds?! eg Yellow-tailed to White-tailed
Black-cockies; Eastern Yellow to Western Yellow and White-breasted Robins.
I disagree. Western Spinebill vs Eastern Spinebill.
Splendid Fairy-wren vs Superb Fairy-wren. Red-capped Parrot vs
??? And Western Rosella and Red-eared Firetail hold their own.
_________________________________________________________________
Frank O'Connor Birding WA http://birdingwa.iinet.net.au
Phone : (08) 9386 5694 Email :
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David James,
Sydney
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