Help with Bird ID please

To: "'David James'" <>, "'Mike Carter'" <>, "'Nikolas Haass'" <>, "'Peter Madvig'" <>, "'M & P Potter'" <>, <>
Subject: Help with Bird ID please
From: "Jeff Davies" <>
Date: Mon, 28 Nov 2011 12:48:05 +1100
G'day Dave,

I really wonder sometimes about the fresh white fringed back feathers as
indicating immaturity.
I now have lots of photos of birds showing this with strong dark bars
forming the breast band, but combined with unambiguously completely dark
under-wing coverts, eg adult or certainly well past 2nd year, but have no
photos of winter adults from Australia for this time of year not showing it,
have the books definitely got this right?. I would also suggest that the
dorsal primaries base wing flash is not visible on the folded wing because
the outer vein of each flight feather overlaps the white shaft of the
underlying feather in each case.
It's really important that if anyone managed photos of this bird showing the
under-wing that they share them with us to assist sorting out Jaegers on the
wintering grounds. I see the lack of wing moult as the most interesting
aspect of this bird, but I'm not sure whether it ages the bird or not. 

Cheers Jeff.

-----Original Message-----
 On Behalf Of David James
Sent: Monday, 28 November 2011 8:45 AM
To: Mike Carter; Nikolas Haass; Peter Madvig; M & P Potter;

Cc: Martin Cocker
Subject: Help with Bird ID please

I tend to agree with Nikolas that it is an Arctic, although I haven't any
experience judging the amount of white wing flash in the folded wing of
standing jaegers.
I definitely agreewith Mike that it is not an adult. Although the resolution
is not great, it appears that the wing coverts and flight feathers are very
worn. Conversely, the mantle feathers are a mix of worn and new feathers.
The new feathers are darker with narrow white fringes. These are not
retained juvenile feathers they are new feathers. They are not adult
feathers because the white fringes are an immature trait that occur in
juvenile, 1st and supposedly some 2nd yr birds. Looks like some of the
median coverts and the remainder of the mantle are newer than the primaries
but older than the freshest mantle feathers. My interpretation is that the
primaries, secondaries, greater coverts and tail are retained and worn
juvenile feathers, the worn head and body feathers and median coverts are
1st winter/summer, and the new mantle feathers are 2nd winter. The bird must
have hatched in mid 2009, as Mike determined.  
Mike, I hadn't notice the statement in Malling Olsen & Larsson that white
tips to juvenile primaries are diagnostic of Arctic. It's a little hard to
make out, but the last photo in that book is a juv Long-tailed with white
tips to the primaries. In the  Windang bird I think the retained primaries
are too worn and bleached to have retained any original white-tips. If there
is a faint impression of pale tips it may be due to fraying and bleaching of
the tips.  

David James, 


From: Mike Carter <>
To: Nikolas Haass <>; Peter Madvig <>;
M & P Potter <>;  
Cc: Martin Cocker <> 
Sent: Sunday, 27 November 2011 11:08 PM
Subject: Help with Bird ID please

I agree with Nikolas that this is a pale morph Jaeger in very worn plumage,
definitely not a Pomarine Jaeger, most probably an Arctic Jaeger rather than
a Long-tailed (because of the pale blaze - but there is only a small amount
of white at the base of the primaries which leaves me a little unsure).
However, I have more of a problem accepting that it is an adult as the white
spots on the mantle look to be remnants of juvenile barring the presence of
which I can't explain in an adult. Perhaps Nikolas or others can. Therefore
I would be happier considering this to be an 18 month old bird in second
winter plumage, two or three years short of a full adult. But another
perhaps age related feature is the white tips to the primaries. When in
juveniles these white tips form a series of chevrons they are said to be
diagnostic of Arctic Jaeger (Olsen & Larsson 1997).
Jaegers are notoriously difficult to ID and photographs of open wings
particularly underwings are very helpful in this process.

Mike Carter
30 Canadian Bay Road
Mount Eliza  VIC 3930
Tel  (03) 9787 7136

<Prev in Thread] Current Thread [Next in Thread>

The University of NSW School of Computer and Engineering takes no responsibility for the contents of this archive. It is purely a compilation of material sent by many people to the birding-aus mailing list. It has not been checked for accuracy nor its content verified in any way. If you wish to get material removed from the archive or have other queries about the archive e-mail Andrew Taylor at this address: andrewt@cse.unsw.EDU.AU