More on terns

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philbattley
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Joined: Wed May 20, 2009 2:21 pm

More on terns

Postby philbattley » Tue Mar 02, 2010 12:13 pm

Or should that be "Morons on terns..."?

All this talk of Common Terns reinforces how little I know about identifying them in NZ, so here are some shots of a tern taken at the Manawatu Estuary last Monday. It just happened to be floating on a log in between me and the godwits that I was actually there for. I make no claims that it is a Common and would be happy as for someone who knows to point out to me why it is a White-fronted (if indeed it is). I know that at some times of year White-fronts can have many hallmarks of Commons. I'm just interested to know what people think of a bird like this. There was no other tern on the log for a direct size or stance comparison.

Cheers, Phil
tern sp IMG_2795 700.jpg
tern sp IMG_2795 700.jpg (136.41 KiB) Viewed 3600 times
tern sp IMG_2807 700.jpg
tern sp IMG_2807 700.jpg (153.31 KiB) Viewed 3600 times
TonyWilson
Posts: 69
Joined: Fri Aug 14, 2009 3:31 pm

Re: More on terns

Postby TonyWilson » Tue Mar 02, 2010 1:13 pm

Hi Phil,
I'm no expert on these guys but it does look like a Common Tern to me. A good field mark being the small patch of black in front of the eye and the area of black behind the eye that extends below the ear coverts which differs from that in White-fronteds. I'm sure Sav and Brent will be able to give a more definitive answer.
Cheers, Tony.
Rob
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Joined: Sat Jul 04, 2009 9:10 pm

Re: More on terns

Postby Rob » Tue Mar 02, 2010 1:39 pm

Very dark outer primaries, Common Tern seems very likely.
Rob
jrstewart
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Joined: Mon Jul 06, 2009 7:17 pm

Re: More on terns

Postby jrstewart » Tue Mar 02, 2010 2:57 pm

Hi Phil,

Looks like a Common to me. Carpal bar more distinct than W-f, outer primaries darker, tail (I think) shorter than wing tips. I find head pattern more difficult for separating these two. Silver wash darker on Common than W-f, but this is also difficult unless side by side for comparison.

Cheers,

John.
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Brent Stephenson
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Location: Havelock North, New Zealand
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Re: More on terns

Postby Brent Stephenson » Tue Mar 02, 2010 3:14 pm

Hey Phil,

I'll try re-writing that response after my computer froze for the second time today (NEVER EVER BUY A DELL!).

I think you probably have another common tern there, so apparently they are common! Your bird may well be the same as Igor's but we'd need a photo of the right side of the head for comparison. Your bird does have the two old dark primaries in the right wing though which is consistent.

I think Tony is probably right with the comment on the dark markings around the eye and ear coverts, your bird also shows that 'frosting' appearance of the receeding cap, rather than the 'blocky' appearance of the WFTs. The medium grey upperparts are also good, compared to the paler grey of WFT, as is the general stance, small round headed appearance, and dark bend in the folded wing. The problem area we discussed in emails before about the tertials is also good here, with this bird showing slight pale fringes to the tertials, whereas in WFT these often have wide pale fringes, but have prominent dark centres.

Looks good to me, and Sav will no doubt have a couple of comments as he is due home soon.
Cheers,
Brent Stephenson
Wrybill Birding Tours, NZ - Great birds, real birders
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philbattley
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Joined: Wed May 20, 2009 2:21 pm

Re: More on terns

Postby philbattley » Tue Mar 02, 2010 4:19 pm

This may well be Igor's bird. RH side view and closeup of the head from the same shot are below. Paddy Latham also e-mailed as below:

"Hello Phil. Well spotted ! With such excellent photos I don't see any problem with identifying your tern as Common. For a start you have shown the main primary (P10) so well, with its very thick ,dark inner web, that it couldn't be anything else (perhaps I am sticking my neck out there ! ).If you look carefully you can see the dark outer
edge to the visible outer rectrix,too. It has the dark carpal bar to be expected in a Common
Tern in winter plumage and the pale "front" extends to just above the eye which is also
typical of Common.Although some of these points are also common to Arctic Terns, e.g. the
dark carpal bar and dark outer rectrices ,Arctics do not have such wide dark inner edges to
outer primaries and the crown would be pale well past the eye to the hind-crown.Besides,
the legs on your bird are too long for Arctic,the bill a shade long and heavy and the crown
rather flat and "snakey" looking - Arctic tends to look more domed . Anyway,for what it is worth
that is my opinion but to be really sure send in a UBR form to the Rare Birds Com. and see
what they say. Cheers.Paddy. "
tern sp IMG_2810 head.jpg
tern sp IMG_2810 head.jpg (141.04 KiB) Viewed 3540 times
tern sp IMG_2810 700.jpg
tern sp IMG_2810 700.jpg (139.01 KiB) Viewed 3540 times

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