Oops, mea culpa! I accidentally switched around the field marks of the juvs.
And yes, thanks for your comment, Jeff, I expected a lot of variation within
populations. Tony didn't only have a look at the numbers of mirrors but also
their shape as well as the shape of the tongues. One of the papers Tony
mentioned is Johnstone RE, Rec. West. Aust. Mus. 1982.10 (2): 133-165.
Cheers,
Nikolas
----------------
Nikolas Haass
Sydney, NSW
________________________________
From: Jeff Davies <>
To: 'Tony Keene' <>; 'Birding-Aus'
<>
Sent: Tuesday, June 28, 2011 4:50 PM
Subject: Gulls and Terns in Sydney
G'day Tony,
Interested to see the photos Tony if you haven't already headed off to
Adelaide.
Three spots is the norm for adults in SE Australia however, the other
northwest half of Australia is more likely to have two window spots, it is
the norm in northern(including Darwin?) and north/west Australia. It
wouldn't be impossible to see an adult Silver in SE Aust with only two
spots. Immatures in SE Aust, including 1A, also show only two spots.
Scopulinus has a shorter bill, this would be the most obvious difference
with adults that you should look for, but if you start looking you will note
quite a lot of variation within your typical flock of Silvers.
It's the juv of scopulinus that lacks the tail band not the other way
around, this is another good feature and would hold through to 1B 1A?.
Cheers Jeff.
-----Original Message-----
From:
On Behalf Of Tony Keene
Sent: Tuesday, 28 June 2011 3:52 PM
To: Birding-Aus
Subject: Gulls and Terns in Sydney
I've done a fair bit of snooping around the literature and I'm almost
certain it was a Red-billed Gull. I'm off with work for a few days to
Adelaide and I'll get some more work done on it. When I get back, I should
be able to let everyone know what I've got and why I reckon it's an RBG.
Cheers!
Tony
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