In reply to Richard’s quiz: 1, it is
rounded, therefore 2, it is a juvenile (but not just on the shape of the
feather), and 3, A. because some student from the ANU with access to a mist-net
caught it down the coast and brought it up to Canberra to stir everyone up? B.
because it likes that particular Banksia ericifolia? I was with Demetrios
yesterday when he took the photo. It does not look all that well, and as Demetrios
said, was attacked quite vigorously by about half a dozen New Holland
Honeyeaters. It looked rather like a Thugby Union maul for a stage, with warms
and legs, oops, sorry, that should be wings and legs, going in all directions. Still,
when not being harassed, it was quite agile and had no trouble flying and
chasing flying insects in the canopy of the Brittle Gums above its
favoured Banksia. Despite what some people are writing about this, and
the White-fronted Honeyeater, neither are rare birds. They are both common
species that happen to be vagrants in the ACT at present. Birds, as far as I
am aware, do not recognize our political boundaries!
Mark
From:
[
Sent: Monday, 23 July 2007 11:16
AM
To:
Cc:
Subject: [canberrabirds] alula and
ageing of honeyeaters [SEC=UNCLASSIFIED]
I have received an enquiry on ageing honeyeaters and
thought I would reply "on-line". I have summarised the technique that
I applied when ageing the White-fronted HE using Julian's great photo- http://www.flickr.com/photos/ozjulian/768995732/
The
shape of the tip of the longest of the alula feathers has been shown to be
diagnostic of age in honeyeaters (excluding the melithreptus honeyeaters).
James Matthew who was systematically examining plumages of birds in museums
while working on HANZAB with Birds Australia made this discovery and published
an article in Corella. James & I spent time banding and field testing this
technique.
The
alula is located adjacent the greater coverts and on the leading edge of the
wing. It consists of 2-3 feathers that stickout a little in flight especially
when braking, hovering and manoeuvring.
What
James discovered was that the shape of longest alula feather varies according
to age. It is rounded in juvenile plumage and pointed in adult birds. The use
of this to age birds in the field requires close scrutiny (ie in the hand or
thro' the excellent photos presented in this forum). Another factor is when and
to what extent the juveniles lose their juvenile plumage (post-juvenile moult).
In a good season this may occur 2-3 months from fledging. In a poor season
resources seem to limit the extent of post-juvenile moult in autumn. It is
common place for juveniles to moult only their outer 6 of their primaries (most
important flight feathers) during post-juvenile moult. The alula usually is
replaced in post-juvenile moult and gets an intermediate alula with a sharper
point. The sharpness of this intermediate alula feather varies. The next
complete moult occurs during the following summer/autumn (bird 12 to 18 months
old) and my banding data shows that this intermediate alula is generally
replaced by a sharply pointed alula.
The
reason/advantage for this age dependant shape of alula is not known.
Now
using Dimitris' excellent photo of LWB below applying all that to answer this
quiz:
- what shape is the tip of
the longest alula feather (see arrow)?
- how old is it?
- why is it here in Canberra?
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