Hello Mike,
Thank you so much for replying to my request. I'm attaching my K I image that
should have been attached to the original but was removed somehow in
birding-aus.
I'll agree, your bird's eye has a greenish tinge but it is also rather dark and
dull and in my opinion, a probable young bird.
I've been looking at the books on this one and what a can of worms! In HANZAB
you can take your pick in the text on soft parts and in the plate, it shows
maculatus with a yellow eye, which is wrong. The new CSIRO "guide" opts out
altogether on iris colour in the text and the plates are really too small be of
any use on this subject. What a pity this book wasn't published as a concise
handbook in A4 format. They obviously have all the information but it has been
compromised by shoehorning into too small a space.
What I am fairly sure about is that age is a factor here as it is with many of
our small birds - we know so little because so few of our birds have been
studied in detail.
I have a wide range of pics of this species and I'm attaching a few examples
The first two are Brown Scrubwrens from Tasmania. The first one is an adult
male at the nest - I would describe that iris simply as yellow.
The second bird at the same nest I always assumed to be a female (on plumage)
but it has an olive coloured eye - such dull colours are usually characteristic
of younger birds and it is much more likely to be a helper than the adult
female, or if it is the female it is a younger bird. I don't expect the sexes
to have different coloured eyes as adults. This eye colour reminds me of your K
I bird.
The next pic is what I regard as a classic frontalis and I would describe that
as pale yellow - virtually all east coast birds are like this, maybe a bit
darker as you go north.
The last is the old "Buff-breasted Scrubwren" of the 1926 Checklist from
northern NSW, slightly darker yellow.
I guess what I am on about here is the difference between "Spotted" and
"unspotted" birds. All the Spotted ones I've seen have the pale blue eyes,
which gives them a totally different (to me) look.
So. how long do they take to become adult ( by eye colour )? I'd say at least
two years.
I guess I'm on the same bandwagon as my recent comments on Eastern Whipbirds.
Most of the books get that one wrong and show adults with brown eyes, whereas
in fact they are cream. How long it takes nobody knows but it's likely to be
similar to the Grey-crowned Babbler which is four years.
What really started this interest was the years I spent with Ian Rowley
studying corvids and choughs, both of which can be aged by eye colour, a very
handy indicator when you are looking at life history. We worked with birds we
banded in the nest, so we KNEW how old they were. Getting to the Australian
Raven's nests was interesting, I can't even lift a rope ladder any more, let
alone climb one.
Cheers
Graeme
Spotted Scrubwren from Kangaroo Island - eyes pale blue
>
Brown Scrubwren male at nest, eyes yellow. I assume this is an adult.
Brown Scrubwren at nest, probable immature, eyes olive.
White-browed Scrubwren, Gloucester NSW. eyes pale yellow. Virtually all east
cost birds are like this,
White-browed Scrubwren. Tooloom northern NSW subsp.laevigaster - eyes yellow
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