Like many Melbourne-based birdwatchers, I spent more time looking at ducks
today at Werribee than I have for ages. Didn't get a sniff of a Baer's
Pochard, but as a consolation, found what could well be a female Northern
Shoveller. Simon Mustoe and I got moderately good looks at it in failing
light late this afternoon, and although we haven't completely worked it out
yet, it seemed suffficiently interesting to justify a birding-aus posting.
The bird was on the big pond immediately south-west of Lake Borrie, mixing
with a group of 100+ Australasian Shovellers. It had two features which
should in theory be diagnostic of Northern Shoveller:
1. Heaps of orange on the bill. The basal quarter or so of the upper
mandible was orange, and the orange ran along the cutting edge of the upper
mandible to almost the tip of the bill. I couldn't work out if it actually
reached the bill tip, but at least 80% of the cutting edge of the upper
mandible was orange. This was the feature that drew attention to the bird;
and was reasonably striking - I lost sight of the bird twice and it wasn't
that hard to relocate it either time. (The underside of the bill was also
orange, but the same applies to female Australasian Shovellers).
2. White outer tail feathers. Only seen from side on, so it isn't easy to
quantify how much white there was, but the resultant white streak was clean
and 2-3 times as broad as the little white smear seen on the Australasian
Shoveller females.
With this combination of features, I don't think the bird could have been an
Australasian Shoveller. But that doesn't automatically make the bird a
Northern. What the bird didn't have was the relatively pale body that I
expect of a Northern Shoveller - they should have slightly broader fringes
and narrower dark centres to most body feathers, making them look a bit more
pale and sandy overall. I can't say I got this impression from the
individual I saw today, except possibly on the undertail coverts and
rear-flanks when it was upending. And I wasn't able to convince myself of a
cause before bad light stopped play. One possibility is that I'm not
sufficiently familar with the full range of plumage variation in female
Northern Shovellers. Another possibility could be that it is a
Northern-Australasian hybrid - there has been a male Northern Shoveller at
Werribee for several years, so there have presumably been opportunities for
interbreeding.
One thing I am sure of is that this wasn't the male Werribee Northern
Shoveller in eclipse plumage - it had a dark eye and not a trace of any
male-like plumage. It also had fully grown wings and flew readily (male
Shovellers are moulting and flightless through most or all of the brief
period when they are in eclipse plumage).
I don't think we got enough detail to clinch this ID, but maybe the
Pochard-seekers will be able to relocate it and work it out over the next
few days. Please let me know if you do! I'd also welcome any thoughts on the
Shoveller ID problem.
Cheers, Danny
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