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: Herring or Thayer's?  ( 6130 )

Greg Neise

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Herring or Thayer's?
« : November 03, 2008, 03:41:41 PM »
Randy and  I found this bird at North Point Marina late yesterday afternoon. At the time I was watching it, I felt that:

a) it didn't have enough white on the upper surface of the primaries, particularly 9 and 10 to be a Thayer's and,

b) the underside of 9 and 10 looked too dark (the camera seems to have captured better details than we actually saw).

I took that into account, along with the bird's small size, dark iris and round head, and felt that it was a small female Herring gull. Anyway, here are the pictures...now I'm not sure, looking at the underside of the primaries if it is too dark...but I haven't seen a lot of 3rd year Thayer's.













« : November 07, 2008, 01:16:39 PM Greg Neise »
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Greg Neise

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Re: Herring or Thayer's?
« #1 : November 07, 2008, 03:49:19 PM »
Here's another shot with a Herring gull behind:

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Steve Spitzer

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Re: Herring or Thayer's?
« #2 : November 07, 2008, 07:57:48 PM »
Well, I am not a good one to ask as birds that I think look more like Thayer's Gulls then some posted as such I am told are Herring Gulls,  but this could be in my opinoin.  Usually when I see Herring Gulls young enough to have a ringed or black tipped bill they do not have near the head streaking of your bird.
Steve Spitzer

Greg Neise

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Re: Herring or Thayer's?
« #3 : November 08, 2008, 09:59:47 AM »
Thanks for posting.

RE: Your last gull:
I can't eliminate 3rd cylce Thayer's gull from the pics,
frame 2 seems to show white tongue tips on P7,6 and 5.


After a bit of researching online and in Gulls of the Americas, and a few helpful tips via ID Frontiers, I'm sticking with my call of Herring gull. There's too much black in the bird's primaries, particularly the underside.
"Only the impossible always happens"
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Chris W

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Re: Herring or Thayer's?
« #4 : November 25, 2008, 08:04:31 PM »
Argument 1: The bird has a dark eye. It's a 3rd cycle Thayer's. By this age, Herring Gulls should have a yellow eye.

Argument 2: The bill isn't delicate enough, there is too much white showing on the primaries, the underside of the primaries are too dark, the legs aren't bright enough. It's a 3rd cycle Herring.

Conclusion: The identification is whatever you want it to be.  It could be one, it could be the other. It could be both. It's not possible to tell.


Problem: Thayer's Gulls are usually impossible to ID from Herring Gulls. Especially in photos.

Solution: Lump both Thayer's and Iceland together and then lump them into Herring Gull. Split them only by subspecies. Problem solved.

Chris W

Michael Retter

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Re: Herring or Thayer's?
« #5 : November 25, 2008, 09:41:57 PM »
There are many problems with Chris W's assertions, which I can only hope were tongue-in-cheek.  Please forgive me if I seem to be pontificating.

First, most Thayer's Gulls are easily separable from Herring Gulls if one has a decent look at the inner webs of the primaries and, most importantly, the experience that helps in doing so.

The bird in the photos is structurally fine for both Thayer's and Herring Gulls.  Comparatively, there are daintier Herrings and chunkier Thayer's.

"More white in the primaries" as a reason to choose Herring over Thayer's is factually inaccurate.  Herring (inland smithsonianus) always has less white in the wing than Thayer's.

Bare part coloration is markedly variable in gulls. There are pale-eyed Thayer's (in fact, a majority do not have dark eyes as adults, but medium eyes), and there are dark-eyed Herrings.  Just as with people, there are gulls with a pale eye on one side and a dark eye on the other.  There are Herrings with bright legs, and Thayer's with dull legs, but most will be dull on anything but a non-adult, anyway.

I hate to beat a dead horse, but it seems to bear repeating:  primary pattern is the best way to move towards identifying a 4-year gull.

Here's a 3rd basic Thayer's I photographed at Winthrop Harbor a couple years ago.  It lacks a dark eye...even in its 3rd year.  What it does have, though, is a perfect primary pattern and supportive evidence in the form of head and bill structure.











Herring and Thayer's Gulls are not close relatives. Genetic data indicate that Thayer's and Iceland form a superspecies (with Kumlien's possibly a hybrid swarm), and California Gull is the sister taxon to that group.  Lumping taxa into a species is not a solution to identifying them; it's running away from the problem. Unfortunately, many birders, especially listers, have this lazy "species-centric" view of taxonomy. Regardless of taxonomic rank, the taxa still exist, and we should want to identify them. Most birders didn't pay attention to Branta canadensis hutchinsii until it became Branta huntchinsii.  Consequently, confusion abounded when Cackling Goose was split.  Many birders had no idea what they were seeing, even though they'd had years of time to study and directly compare the two species.

I agree, Greg, that your gull has a Thayer's-like head and bill structure, but there is much overlap between male Thayer's and female Herrings.  While I'd much prefer to see a spread wing, what we can see of the primary pattern seems to be wrong for Thayer's.  As you said, there is much too much black, but this is not an optimal view.  I think the bird is a Herring, but the photos may not be identifiable; I'll agree with Chris on that point.

« : November 25, 2008, 09:53:41 PM Michael Retter »
Michael Retter
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Steve Spitzer

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Re: Herring or Thayer's?
« #6 : December 01, 2008, 09:26:42 PM »
It lacks a dark eye...even in its 3rd year.  What it does have, though, is a perfect primary pattern and supportive evidence in the form of head and bill structure.

I don't think people should even bother mentioning "supportive evidience".  I have posted quite a few birds with round heads and small bills and been told that they are Herring Gulls because of the wings, an the wings are what make them Thayer's Gulls when they are.  So it is obvious to me that there is no supporting evidence.
Steve Spitzer

Michael Retter

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Re: Herring or Thayer's?
« #7 : December 17, 2008, 08:22:03 PM »
Supportive evidence is just that; it's used to support an identification, not to make one.  That doesn't make it nonexistent.
« : December 17, 2008, 08:32:23 PM Michael Retter »
Michael Retter
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Steve Spitzer

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Re: Herring or Thayer's?
« #8 : December 17, 2008, 09:43:55 PM »
Supportive evidence is just that; it's used to support an identification, not to make one.  That doesn't make it nonexistent.

I disagree. The sentence below is from your earlier post.  The inner webs of the primaries.  So, they can have anything else and it is meaningless.  There are round headed Herring Gulls with smaller bills, but they are Herring Gulls if they do not have the right kind of inner webs. 

First, most Thayer's Gulls are easily separable from Herring Gulls if one has a decent look at the inner webs of the primaries and, most importantly, the experience that helps in doing so.

Steve Spitzer

bill rudden

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Re: Herring or Thayer's?
« #9 : December 18, 2008, 02:27:50 AM »
Supportive evidence is just that; it's used to support an identification, not to make one.  That doesn't make it nonexistent.

Gull ID is like playing poker.  You can have a pair (of field marks) but you need a straight (cluster of field marks) to win.
 I'm always betting on a pair and losing for lack of a straight.

Michael Retter

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Re: Herring or Thayer's?
« #10 : December 18, 2008, 06:35:33 AM »
Most Thayer's, but not all, have small, rounded heads and small bills.  Most Herring Gulls do not.  That's why it's a supporting field mark: when it's there it supports the identification, but it is not enough alone to identify a bird.  And while they can be unhelpful in some cases, in most, they are not.

The end of the sentence quoted was and is the most important part of any bird ID, but especially gull ID:  "and, most importantly, the experience that helps in doing so." You can't just jump in to gull ID and hope to understand everything right away. I remember being very frustrated by gulls when I was starting out, and I still am sometimes.  Patience is a virtue . . . years and years of patience and experience.

Go out and find PERFECT individuals with respect to primary pattern. Then look at bare parts coloration, head shape, bill shape, etc.  You will find that a majority of these birds show the correct supporting field marks.  Some, inevitably, will not.  But the lesson to take home is that most do.

I really like Bill's analogy to poker.  The head and bill shape are like an ace kicker (high card): helpful if you have a so-so hand (a so-so ID).  But if you've got 4 kings (correct primary pattern), then it's rally icing on the cake: no one's got 4 aces because you have one of them. That doesn't mean the ace isn't there. Supporting field marks are not meaningless. If they were, they wouldn't be discussed.  It's not helpful to make blanket black-and-white statements about a subject that is mostly colored with gray.  You just have to know how to discern them, and when is the correct time to apply them (again, stemming from experience).

Supporting field marks also help by directing our attention toward possible candidates.  Head shape, size of the apical primary spots,  and a dark, dusky hood can draw one's attention to a sitting Thayer's candidate when we cannot easily see its inner webs.  More often than not, these supporting characters, especially when used together, lead us in the right direction. These are very helpful clues for people who know how to use them and also understand their limitations.  If they were not so, field guides (and I) would not waste time mentioning them.

« : December 18, 2008, 07:02:38 AM Michael Retter »
Michael Retter
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Steve Spitzer

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Re: Herring or Thayer's?
« #11 : December 18, 2008, 06:53:23 AM »
I am pretty sure that years from now, a round-headed small billed and dark eyed gull will still not be a Thayer's Gull unless it has the correct wing pattern.  At least according to previous posts by you and others.  So those supportive marks rather meaningless.
Steve Spitzer

Greg Neise

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Re: Herring or Thayer's?
« #12 : December 18, 2008, 07:01:20 AM »
I am pretty sure that years from now, a round-headed small billed and dark eyed gull will still not be a Thayer's Gull unless it has the correct wing pattern.  At least according to previous posts by you and others.  So those supportive marks rather meaningless.

Well, yes...but in rare cases, it can work in reverse. Such is the case with the odd gull I photographed at Fullerton last month. It had the correct primary pattern for Slaty-backed Gull, but other supporting evidence strongly steered away...indicating a probable hybrid of some kind.
"Only the impossible always happens"
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bill rudden

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Re: Herring or Thayer's?
« #13 : December 18, 2008, 07:05:15 AM »
Steve take a look at my recent ID post
" low contrast 2nd cycle  gull".
No on is jumping on Thayer's.  I assume because the bird has Herring jizz.

Michael Retter

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Re: Herring or Thayer's?
« #14 : December 18, 2008, 07:07:05 AM »
Steve, you're missing the point, which is that they more often that not SUPPORT a correct identification.  There will always be individuals that are not correct. That's nature.  If 85% of Thayer's have a feature, and only 10% of Herrings do, that IS helpful. Can you not see that?  I don't know how else to explain it . . .
Michael Retter
Fort Worth, TX
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