birding-aus

Cooktown Slaty-backed Gull happily post sitting today

To: Mike Carter <>, Tony Russell <>, BIRDING-AUS <>
Subject: Cooktown Slaty-backed Gull happily post sitting today
From: Nikolas Haass <>
Date: Sat, 23 Feb 2008 00:05:53 -0800 (PST)
Hi Mike and Jeff,

What I wanted to say with my provocative mail is that we obviously had problems 
ID'ing this bird. For me it still could very well be a Slaty-back and I also 
pointed out earlier that I don't like to call everything a hybrid that I can't 
ID - but did we really rule out a hybrid? I do agree that many features speak 
for Slaty-back and that's why I initially ID'd it as such. However, several 
others vehemently ruled out Slaty-back (because of color and pattern of scaps 
and mantle feathers, because of the size and shape of the bill and I think 
there were more mentioned). So apparently it is not a 'straight-forward' ID. So 
after all this confusing back and forth, I really would be curious about the 
results of a DNA analysis!

Nikolas
 
----------------
Nikolas Haass

Sydney, NSW


----- Original Message ----
From: Mike Carter <>
To: Nikolas Haass <>; Tony Russell <>; 
BIRDING-AUS <>
Sent: Saturday, February 23, 2008 6:08:40 PM
Subject: Cooktown Slaty-backed Gull happily post sitting today

Nikolas Haass <> said today
To: "Tony Russell" <>; "Mike Carter" 
<>; "BIRDING-AUS" <>


> Although I was the first one who dared to ID the bird as a female 
> first-winter Slaty-backed Gull (see old posting below), I still would NOT 
> say that we 'SETTLED' on a definite ID.
> We clearly ruled out Thayer's Gull, American Herring Gull (see below), the 
> fuscus complex including Heuglin's Gull (heuglini and taimyrensis), 
> Eurasian Herring Gull, and most of the "yellow-legged gull complex". 
> Moreover, as I indicated a week ago, tail and primary patterns speak 
> against Mongolian and Steppe Gull.
> And also Vega doesn't fit 100%. But - although it was my favorite - does 
> Slaty-back fit 100%? No, it looks good for a Slaty-back, but apparently 
> not 100%! Look at all the divergent comments from experts from all over 
> the world! I think, the final ID at this point should be "possible 
> Slaty-back".
>
> Nikolas

So although you named it several days ago, you are still not 100% convinced?
Please tell us what you consider unsatisfactory in that ID.

Jeff Davies and I will prepare the BARC submission and we are confident that 
we can totally justify that diagnosis. Among significant aspects that you 
didn't address were the plain dark underwing pattern and short primary 
projection beyond tail. Once those two features fell into place for 
Slaty-backed ruling out Vega Gull the one remaining stumbling block was the 
scapular pattern which was more typical of Vega Gull. But now we know some 
Slaty-backs can be similarly patterned there are no contra-indications. The 
presence of that second generation secondary feather noted by Alvaro was a 
bonus. All discriminators are in favour of Slaty-backed Gull. QED.

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


      
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