Thanks Lloyd for a most informative posting. I largely agree, and would
like to add a few points.
Until recent years I think this might have been the most under rated
identification problem amongst Australian birds. A few years ago word got
around that Les Moore considered that this pair could not be reliably
separated in the field at most locations, the Crater being the (one?)
exception. I have not spoken at length with Les but I think this position
is something of an overstatement. nevertheless Les has considerable
experience with both netting and viewing this pair and his caution cannot
be dismissed lightly.
I doubt that I've had anywhere near as much experience with Atherton (ATSW)
as either Lloyd or Les but I have seen it and watched closely on many
occasions at Mt Windsor, Mt Lewis, Mt, Bartle Frere, The Crater (Mt
Hypypamea) and (apparently) at Kirrama in the ranges behind Cardwell. These
sites range from c. 16 deg 40 min to 18 20 S. Presumablt they occur further
s. around Wallaman falls (near Ingham) but they don't occur at Paluma (Mt
Spec).
In the North: From Mt Lewis north
Lloyd's description in his last posting is the best I've yet read. I can
confirm that in the north ATWS differs from LBSW in:
distinct yellow wash to underparts
darker upperparts
I also think that the rump is slightly russet in ATSW, just faintly. Can
anyone confirm this?
I also think the face is darker, not contrasting as much with the crown,
but I'm not completley sure.
I have never found the angle of the bill to be reliable, but I haven't
really looked carefully
Neither nests nor calls are my speciality but I consider that ATSW calls
less, is quieter (softer) and apparently has less of a repertoire than LBSW.
The behaviour is distinctive. It has long been considered that ATWS feeds
on the ground and LBSW feeds along trunks and branches. This symplistic
view was heavily criticised as unreliable a few years ago, critics pointing
out that the had seen ATWS high in trees and LBSW on the ground. While this
is true, ATWS feed predominantly on the ground and if the ascend trees
generally return to the ground before long. At dusk I have seen them flying
from tree to tree at Mt Lewis, but such behaviour is rare. Conversely LBSW
feed predominantly in trees, rarely descending to the ground, and then only
briefly. I've never seen them travel by hopping along the ground. ATWS
never (in my exp.) feeds by fluttering amongst hanging bark or the like
whereas Large-billed routinely does. and, as lloyd pointed out LBSW is
gregarious but ATSW is territorial and only seens singly or in pairs (or
perhaps very briefly in family units). The point is that they can be
easily separated on behaviour if you watch them for long enough to be sure
that you see what they MOSTLY do.
South: Kirrama.
Now it does get a little harder. I think that they occur sympatrically
here. Neither is particularly common, but LBSW is not rare. I saw (what I
thought was) ATSW here twice and netted it once (2 birds). I saw little if
any yellow wash on the underparts, and they were only slightly darker than
LBSW. They had a faint russet tinge on the rump, but it was quite
indistinct. The behaviour was what caught my eye on the free birds.
Unfortunately I did not get to watch them for very long, so I would like to
confirm their presence there when I get time.
I also wonder if perhaps they are harder to identify in the hand, when
behaviour is eliminated and the browns of the feathers wash-out some subtle
colours that "come alive" in the field. Would this explain some of Les'
cautious warnings about field ID?
I suspect, that like Lewin's and Yellow-spotted Honeyeaters, the scrubwrens
replace each other altitudinally. And like the honeyeaters, they may well
be an altitude band where widely they coexist. But what is the altitude?
Where I saw them at Kirrama, near the JCU research station, is at about 600
m.
any further thoughts anyone?
David James
PO BOX 5225
Townsville Mail Centre 4810
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