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Theory basically sound, I'd say, John. It would be great
to have some simple reliable criteria for this, but it seems to be
quite a complex issue. For example, unless nesting the 'resident'
silvereyes tend to flood through in large numbers in the manner of
migrating birds (and some do migrate).
The Schodde/Mason 'Directory' notes the need to take
account of age and plumage wear and the 'hitherto little appreciated fact that
females, though similar to males in size ..., are significantly duller in
plumage'.
Relevant excerpts from the descriptions in the Directory are
as follows (italics as in original):
westernensis (local breeder)
"Crown, lower back and folded wings rich mid citrine, the tone
usually encroaching little on upper back; mantle and upper back
rich mid grey; citrine face with light dusky wash; throat
light citrine-tinged yellow, the tone often restricted to
upper throat; breast clear mid grey, grading to pale to mid dull russet
brown over flanks; ... under-tail coverts off-white, rarely tinged
lemon ...."
lateralis (migrant)
"Crown, lower back and folded wings rich deep citrine, the
tone encroaching little on upper back; mantle and upper back rich
deep grey; citrine face with distinct light dusky wash;
throat pale grey tinged variably pale citrine yellow; breast clear mid
grey, grading extensively deep russet-cinnamon over
flanks; under-tail coverts off-white ..."
Either, then might have an apparently yellowish
throat.
I have scrolled through my silvereye folio and found some
illustrative snaps, but not a really strong example of the striking
'russet-cinnamon' flanks I have seen in the field occasionally (although I could
create one!). I would tentatively say all the below are
westernensis, although the colour has been muted somewhat in the
compression and I don't want to fiddle with it .
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