Tern I.D.

To: "Jeff Davies" <>, "'Chris Corben'" <>
Subject: Tern I.D.
From: "Roger Giller" <>
Date: Wed, 21 Mar 2012 23:37:17 +1100
Hi guys,

Firstly let me thank you all for your efforts and the interesting discussion on this Tern I.D. No wonder I was struggling to identify it just by looking in a couple of field guides! I have added three more images to the album. They were shot in RAW and I have just cropped them and saved as a maximum quality JPEG.
I looked at my images of the roosting birds but they are all Crested Terns.

I have made some measurements of the bill length compared to the bill tip to eye distance from my photos and similarly for a few on-line images of Arctic Terns and Common Terns. The results were: Arctic Tern 58-63%, Common Tern 68-73%, my Tern 72%.

My vote goes to Common Tern, but I'm happy to be corrected if the feathers tell a different story.


-----Original Message----- From: Jeff Davies
Sent: Wednesday, March 21, 2012 6:59 PM
To: 'Chris Corben'
Cc: 'Nikolas Haass' ; 'Roger Giller' ; 'Birding-Aus'
Subject: Tern I.D.

G'day Chris,

I agree with everyone, the general look is Common which is why it took me a
couple of days to raise these questions, eg long body and neck, and longish
bill, although that bill does look rather sharply tapered. I was just
concerned about those primary tips and I am still concerned because I can't
identify a clean set of four Ps behind them, the secondary/primary junction
is discernable. This is why I am keen to see more images so I can put to
rest if this is the birds maintained appearance across multiple images, and
hopefully shed more light on those primaries. If nothing else I am about to
learn more about 1st year Common Tern. Moult stage is generally OK for 1st
year of either species.

Cheers Jeff.

-----Original Message-----
From: Chris Corben 
Sent: Wednesday, 21 March 2012 6:39 PM
To: Jeff Davies
Cc: 'Nikolas Haass'; 'Roger Giller'; 'Birding-Aus'
Subject: Tern I.D.

Hi all

I'm guessing that's P5 and P6. Look at the relative positions of the
tips and think how many more Ps you could fit beyond them. Also, if P3
and 4, I'd expect to see white on the inner webs near the tip in either
species. I think that probably is P4 you can see on the right wing.

Given the extreme backlighting, I'm not surprised to see that much
translucency on a Common, and the new primaries actually don't show much
hint of it, which is not great for Arctic.

It has long been my impression that Common's show a much narrower dark
trailing edge when the feathers are fresh. I think that's because the
feathers darken initially at the tips where the wear is greater. You can
see how the longer new P shows a clear gradation of darkness towards the
tip, which is not what you would see in an older feather.

The jizz is much better for Common, with that rangy neck and fat rear
body, and the head pattern is so typical, with that almost isolated

Cheers, Chris.

On 03/20/2012 11:54 PM, Jeff Davies wrote:
G'day Nikolas,

I can see what you mean and my initial response was also Common, but a
considered look the following day focused in on those fresh primaries they
are a problem looking like that at Ps 3 and 4, is the dark tips real or an
illusion and are they really Ps 3 and 4, also I would prefer them to be
solidly dark but this is a 1st year bird no matter which species.

Is the bill just too long for an Arctic and outside possibility, I'm not
sure, it certainly looks rather sharply tapered but I agree it does seem a
tad long. Some more photos will reveal if this is the only shot of it
looking long bodied or not. The thing to note is that this bird is in
and not at either of the poles so it might influence body volume.

Thought we shouldn't be too quick on this individual without seeing more
images, would like to hear opinions on those two fresh primaries.

Cheers Jeff.

From: Nikolas Haass 
Sent: Wednesday, 21 March 2012 2:10 PM
To: Jeff Davies; 'Roger Giller'; 'Birding-Aus'
Subject: Re: [Birding-Aus] Tern I.D.

Hi Jeff&  Roger,

Yes, it is worth to have a look at more pictures. Would be nice to see the
upperparts, too.

To me it looks too heavy-billed and long-necked for a classic Arctic Tern.
Also I thought that the dark trailing edge of the wing (i.e. tips of p3/p4
in this case) is too diffuse for an Arctic Tern. Do you think the
secondaries are translucent enough for Arctic? What about the dark grey
outer rectrices?

Just a quick thought. Don't have my ornithological literature here at



Nikolas Haass

Sydney, NSW


From: Jeff Davies<>
To: 'Roger Giller'<>; 'Birding-Aus'
Sent: Wednesday, March 21, 2012 1:06 PM
Subject: Re: [Birding-Aus] Tern I.D.

I'm wondering if we can discount this bird as a possible 1st year Arctic
The left wing is in a really bad way with a big chunk of primaries missing
in the middle.
I strongly suspect that the two fresh primaries that appear to show narrow
dark tips are primaries 3 and 4, if that was the case it is problematic
Common which typically doesn't show dark tips until around primary 5. Note
also how transluscent the wing is, and how the dark tips don't feed onto
leading vein of the feathers. Admittedly the wing is rather compromised
however but I thought that Arctic may be worth considering.
Have you got any more images of this bird Roger, no matter about image

Cheers Jeff.

-----Original Message-----
 On Behalf Of Roger Giller
Sent: Monday, 19 March 2012 12:00 AM
To: Birding-Aus
Subject: [Birding-Aus] Tern I.D.

Can anyone assist me in identifying this Tern I photographed at Stockton
Breakwater, Newcastle? I was not birding at the time and had no binocs,
the camera. I just got around to looking at the photos from the day.





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