[NatureNS] Re: "of interest to Gull ID freaks" (long and boring to most?)

Date: Mon, 23 Oct 2006 11:31:40 -0300
From: iamclar@dal.ca
To: naturens@chebucto.ns.ca, Richard Stern <sternrichard@gmail.com>
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All:

Here are a couple of footnotes to Richard Sterns thoughtful post on maddening
gulls. (Warning: those repelled by gull confusion should tune out.)

Quoting Richard Stern <sternrichard@gmail.com>:

> As far as I recall there are no good records of YLGU for NS, although
> approx. 10 years ago there was a good candidate that appeared at the
> NW Arm in Halifax. However, after various larophiles had seen the
> pics, they were thought to be a HEGU with yellowish legs (possibly an
> "omissus" form of the N. European HEGU - which in itself would be
> fascinating).

That is correct.  The bird was nicely photo's by Christine and, at my
urging we published a note in the lamentably terminated "Birders Journal,"
namely as: CORNELL, C., K. TUTT, AND I. A. McLAREN. 1995. Probable
Yellow-legged Gull in Nova Scotia. Birders Journal 4: 302-304.

A couple of European experts thought it was not a YL Gull, but more likely a
yellow-legged Herring Gull, as Richard indicates. And I believe they are
correct.  A further complication is that, as some have seen, our N. Am.
Herring Gulls sometimes have quite yellowsih legs, especially in spring,
possibly a result of diet.
>
> While we're at it, is there any known way to visually tell N.American
> HEGUs  from European ones in adult plumage? Apparently they are
> genetically quite distinct, and almost certainly different species.

It was formerly thought easy enough based on the white "windows" in wingtips -
Am. with restricted white spot on the outer one (P10), and Eur. with an
elongate one.  However, although this was accepted for years, it was actualy
questioned in an article I've come across from a 1902 article in "The Auk." 
Then, two paramount gullgurus - published an article (Jonnson, Lars, and B.
Mactavish. 2001. American Herring Gulls at Niagara Falls and Newfoundland.
Birders Journal 10(2): 90-107) that showed great variation in wing-tip pattern
in N. Am. Herring Gulls.  Finally, Bruce Mactavish e-mails me that he and Peter
Adriaens had trried to solve the problem in an article in "Dutch Birding. " (My
son Jamie subscribes, and I'll try to get a copy of the article. Here is
Bruce's summary of what is certainly the best word on the subject

"Peter Adriaens and I did a little comparison of adult European Herring Gulls vs
Newfoundland Herring Gulls.  It was written up in painful detail in Dutch
Birding sometime in the last 3 years (not 2005 or 2006).  If I had my issues
organized I could find it.  There is no sure fire way to separate the two on
wing tip pattern alone but some consistent differences were black 'bayonet'
shapes in leading web of P6-P8.  And white tips on P10 far more common on
European than Newfoundland birds.  There were other general differences. You'll
have to hunt down the article."

Finally, even juvenile Eur. vs. Am. Herring Gulls, believed to be relatively
easy to distinguish, appear more confusing than previously thought. Bernard
Burke's photo site has pics of an individual at Sullivans Pond that he, and I,
thought was a good candidate for Eur. Herring Gull, but two posts from Eur.
gullophiles conclude that, although close, it is most likely a pale Am. gull. 
Yet another keen birder from Texas thouught it might be a "vega" Herring Gull
from Siberia or Alaska.  Bruvce Mactavish still thoinks it resembles a Eur.
bird more closely.

So, no wonder many birders are turned off by gulls.  But those who like them,
like them a lot.

Cheers, Ian McLaren


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