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   Slaty-backed Gull (Larus schistisagus) - SBGU (recent eBird sightings, view CBRC records, range map
)

  1. Slaty-backed Gull Half Moon Bay LINK
    DATE: Mar 1, 2018 @ 4:33pm, 5 month(s) ago
    Hi all, ††I found an adult Slaty-backed Gull at the mouth of Frenchmanís Creek this afternoon. Malia DeFelice and Chris Hayward were birding themselves, and they were able to drop in almost immediately and see this bird. It is an adult, on the slightly paler end of back color but still a tad darker above than Western Gull. Features include: Structurally bulky, deep bellied, big breasted and relatively long-winged. Eye pale Orbital ring reddish like the red gonys spot on the bill Streaking on head and neck a warm cinnamon color, becoming dense on the nape and rear neck. Legs dark pink. In flight white tongue tips (string of pearls) to the 8 th primary. This bird had no mirror on 9 th primary as Slaty-backed can have. Below, wings silvery and string of pearls clearly visible, primary tips darker than primary bases. Black to 5 th primary. † Photos are here: https://ebird.org/view/checklist/S43300221 † Alvaro Alvaro Jaramillo alvaro@... www.alvarosadventures.com †
  2. -back to top-
  3. Slaty-backed Gull in Monterey 5 February LINK
    DATE: Feb 5, 2018 @ 9:59pm, 5 month(s) ago
    Hi Birders
    
    This morning I found a second cycle SLATY-BACKED GULL at the Marina Landfill in Monterey County. So far this season, ourlandfill hasn't proved quite as fruitful as last year, with increased gull-deterrent activities and less abundant rain puddles. But, it was good for at least an hour this morning with the Slaty-backed, a Glaucous Gull, and a Vega Gull candidate amidst 1500-2000 other gulls.
    
    Details and photos in the eBird list.
    
    https://ebird.org/view/checklist/S42517502
    
    Good birding,
    
    Blake Matheson
  4. -back to top-
  5. Slaty-backed Gull at Pilarcitos Creek, Half Moon Bay LINK
    DATE: Mar 2, 2017 @ 10:09pm, 1 year(s) ago
    Adult SLATY-BACKED GULL was still present this afternoon at the mouth of
    
    Pilarcitos Creek in Half Moon Bay, San Mateo County. It had flown out to
    
    sea earlier but returned to the sand flats around 4:30pm.
    
    A few photos at...
    
    https://fog.ccsf.edu/~jmorlan/Slaty-backedGullP1090802a.htm
    
    Access is from the Venice Beach Parking lot.
    
    --
    
    Joseph Morlan, Pacifica, CA
  6. -back to top-
  7. Possible first-cycle Slaty-backed Gull in Marina--28 January LINK
    DATE: Jan 28, 2017, 1 year(s) ago
    Hi all,
    
    Blake Matheson, Cooper Scollan and I found this interesting gull at Marina Landfill today. Looks like a good candidate for first-cycle Slaty-backed to me, but given how difficult first-cycle gulls are (especially this species!), I'd be very open to hearing more opinions on this bird. It is included now tentatively as Slaty-backed on this checklist:
    
    http://ebird.org/ebird/view/checklist/S33997486
    
    The first-cycle Lesser Black-backed Gull continues there today as well, along with a Glaucous Gull.
    
    Thanks
    
    --
    ===========
    Brian L. Sullivan
    
    eBird Project Leader
    www.ebird.org
    
    Photo Editor
    Birds of North America Online
    http://bna.birds.cornell.edu/BNA
    -------------------------------
  8. -back to top-
  9. Slaty-backed Gull continues LINK
    DATE: Jan 12, 2017 @ 8:54am, 2 year(s) ago
    The second-cycle Slaty-backed Gull continues on the little beach at Pt. Pinos this morning. It has been stand-offish from the flock and is often just over the lip of the parking lot. The flock itself is amazing with lots of Glaucous-wings, a GWGUxGlaucousGull hybrid, lots of Herrings, at least 18 Thayer's, and a BL Kittiwake. More kittiwakes offshore. Once tourists venture onto the beach, though, gulls will scatter. Don Roberson & Rita Carratello
    
    Don Roberson
    
    Pacific Grove CA
    
    http://creagrus.home.montereybay.com/
  10. -back to top-
  11. Re: [CALBIRDS] Slaty-backed Gull at Pt. Pinos, MTY LINK
    DATE: Jan 10, 2017 @ 10:55am, 2 year(s) ago
    Rita Carratello and I refound the second-cycle Slaty-backed Gull at the
    
    little beach at the tip of Pt. Pinos early this a.m., before the
    
    tourists reached it. It is the same bird photographed by Blake Matheson
    
    at this spot yesterday. While we sat in our car, the gull decided to
    
    walk right past us to drink from a rain puddle, then walked into the
    
    street, and then flew to rocks below the next parking area to the south,
    
    where it went to sleep. It was still present there an hour later, per
    
    eBird postings.
    
    Our checklist is at
    
    http://ebird.org/ebird/view/checklist/S33581953
    
    Don Roberson
  12. -back to top-
  13. Slaty-backed Gull at Pt. Pinos, MTY LINK
    DATE: Jan 9, 2017 @ 1:16pm, 2 year(s) ago
    Greetings Birders
    
    Today I was surprised to find what looks to be a Slaty-backed Gull at Pt. Pinos, Monterey County. Details and photos are in my eBird list, here: http://ebird.org/ebird/ view/checklist/S33566603 . I got the word out to locals this morning, but I'm not sure if it's been looked for or re-found. In my view, immature rare gull identifications are tentative in perpetuity, so this bird could always be proven to be something else. But for now I'll keep it as SBGU to ensure the word gets out.
    
    Good birding,
    
    Blake
    
    --
    
    Blake T. Matheson Monterey Peninsula
    http://www.flickr.com/photos/ 34328261@N02/
    http://montereyaudubon.org/ volunteers/blake-matheson.html
    "If you save the living environment, the biodiversity that we have left, you will also automatically save the physical environment, too... If you only save the physical environment, you will ultimately lose both." E.O. Wilson.
  14. -back to top-
  15. SLaty-backed Gulls in California LINK
    DATE: Mar 5, 2014 @ 9:24pm, 4 year(s) ago
    Hi All,
    
    Just thought I would let my Calbird buddies have a link to my Flickr photo site that I have recently started. All those rare birds and no one to share them with too often. I will be adding many photos over the next few years as that is how many images I think I have in my archives from years of birding and that does not even count my several boxes of slides, doh!. I will try and put up most of the rare and unusual stuff first as they are the most fun and interesting to deal with. Check back from time to time or I will post something eventually when I do certain sets of rarities and such.
    
    This link is to many of the Slaty-backed Gulls that I have been fortunate to photograph over the last few years in Northern California. Some are descent quality, but most are for documentation and to learn from gleaning over the images from time to time only. Please let me know if the link does not work.
    
    http://www.flickr.com/photos/toddeasterla/sets/72157640118700796/
    
    Enjoy and learn!
    
    Todd Easterla
    Fair Oaks, Ca.
    
    
  16. -back to top-
  17. SLATY-BACKED GULL-SAN MATEO COUNTY LINK
    DATE: Mar 5, 2014 @ 7:09pm, 4 year(s) ago
    Sent for Ron Thorn by Leonie Batkin
    
    This morning I was observing many gulls coming in from the coast to bathe in Upper Crystal Springs Reservoir. At around 10:30am an adult SLATY-BACKED GULL flew in and stayed
    for about half an hour. The Slaty-backed Gull took flight and passed by me at eye level and then circled above before flying off towards the San Francisco Bay with other gulls. I was viewing the gulls along Canada Road about one-quarter mile south of Highway
    92 in San Mateo County.
    
    A detailed documentation will be sent to the CBRC.
    
    Ron Thorn
    Redwood City
    
    
  18. -back to top-
  19. SBGU update (Humboldt) LINK
    DATE: Mar 4, 2014 @ 9:33pm, 4 year(s) ago
    The putative 1st-cycle SLATY-BACKED GULL found by Tristan McKee continues
    at the Arcata Library as of yesterday. This bird is reliably chummed in
    with bread (conveniently available across the street at Safeway). Photos
    at http://www.flickr.com/photos/92833762@N03/sets/.
    
    Ken Burton
    Eureka
    www.norcalnature.com
    
    
  20. -back to top-
  21. Re: [CB] Solano County Lesser Black-backed Gull, Glaucous Gull, etc. LINK
    DATE: Feb 14, 2014 @ 6:09pm, 4 year(s) ago
    This morning Dan Singer and I checked out the B & J Landfill at 6426 Hay
    Rd, Vacaville. Thousands of gulls were present but we were able to study
    only a small fraction of those birds resting in the fields on the north
    side of Hay Road across from the landfill.
    
    We found an adult LESSER BLACK-BACKED GULL which is apparently a first
    record for Solano County. Distant but identifiable photos are at...
    
    http://fog.ccsf.edu/~jmorlan/LesserBlack-backedGullP1150479.htm
    
    We also saw a very pale GLAUCOUS GULL, apparently 2nd cycle. Photo at...
    
    http://fog.ccsf.edu/~jmorlan/GlaucousGullP1150489.htm
    
    There was also at least one adult WESTERN GULL with the flock.
    
    Other birds of interest in eastern Solano County were a flock of about 40
    MOUNTAIN PLOVERS seen only in flight at the east end of Robinson Road. We
    had a close encounter with a ROUGH-LEGGED HAWK along Flannery Road just
    east of Hwy 113. Several FERRUGINOUS HAWKS were also in the area.
    
    CLIFF SWALLOWS have arrived with several exploring a culvert along Flannery
    Road.
    
    Good luck!
    
    On Fri, 7 Feb 2014 15:30:48 -0800, John Sterling <jsterling@...>
    wrote:
    >Roger Muskat called to report an adult Slaty-backed Gull, a Glaucous Gull and a possible adult Kumlein's Iceland Gull at a pasture bordering the landfill on Hwy 113 and Hay Road in Solano County, just south of Dixon.
    >
    >John Sterling
    >VVVVVVVVVVVVVVVVVV
    >
    >26 Palm Ave
    >Woodland, CA 95695
    >530 908-3836
    >jsterling@...
    >www.sterlingbirds.com
    --
    Joseph Morlan, Pacifica, CA jmorlan (at) ccsf.edu
    Birding Classes start Feb 11 http://fog.ccsf.edu/jmorlan/
    
    
  22. -back to top-
  23. Re: [CALBIRDS] Cook Inlet vs. Slaty-backed: a summary LINK
    DATE: Feb 9, 2014 @ 2:23pm, 4 year(s) ago
    Tristan,
    I'm glad you are working on this.
    
    A few of my thoughts:
    1) I remain very skeptical regarding the use of "structure"-- head shape, bill shape, wing shape, belly shape, leg length, etc. in distinguishing between SB and Gl-W x Herring (Cook Inlet). They just seem too close to each other-- and closeness that is swamped by the degree of variation that occurs naturally, as well as the degree of variation that occurs in our impressions and especially in still photos (which can impart radically different structural impressions of the same bird).
    2) I, unlike most others, am a believer that the bits of "adult gray" we find in incoming scaps of young birds are indeed the same shade of blue-gray as on adult birds. However, when it's a single feather (or part of a feather) surrounded by gray-brown and white, judging the shade of that blue-gray is difficult. That said, the small spot of blue-gray on your Arcata bird seems to be SB.
    3) I've posted a comparison of presumed SB's (from Japan) and presumed Gl-W x Herrings (from Calif) at http://www.tertial.us/gulls/sbgugwhe.htm, asking for feedback if anyone sees clues on how to distinguish them. I've received very few replies. They have focused on structure issues and the gape curve idea (which is intriguing but not terribly convincing if you look at the pics). I was hoping for someone to point out a diagnostic feature in the median coverts! ;)
    
    So that leaves me, personally, with this: I have no structural or plumage marks to use (convincingly) and am pretty much in the camp of what John Dunn once told me, "I don't identify them until they have some slaty in the back."
    
    But your one feather is enough for me (almost-- I'd like a couple more feathers to be sure, ideally bigger ones).
    
    Check out my pics at http://www.tertial.us/gulls/sbgugwhe.htm and tell me if you think any of the Calif birds are actually Slaty-backed!
    
    On Sun, Feb 9, 2014 at 2:42 AM, Tristan McKee <atmckee@...> wrote:
    Hi Calbirders,
    
    Regardless of its identification, the juvenile gull frequenting downtown Arcata this winter provides an unparalleled opportunity to ponder Slaty-backed characters up close, in direct comparison with Glaucous-winged and Herring gulls and their apparent hybrids. These hybrids are the source of the popular notion that first-cycle Slaty-backed Gulls simply cannot be identified here, in the absence of incoming slaty mantle feathers. However, the Arcata bird shows numerous traits that differ from both species and are not intermediate between them. I have also just uploaded a zoomed-in photo that shows an incoming bluish-slate-colored mantle feather (I am unsure if this is diagnostic, so I'm not placing much weight on it at this point):
    http://m.flickr.com/#/photos/101791769@N08/12394547043/
    
    Since development of identification criteria for this cycle has largely occurred on the internet and is widely scattered, I have summarized the results of my work this winter to distinguish Slaty-backed from "Cook Inlet" hybrids. A more detailed account will be published shortly, but I figured hey, it's February, and there is still time to put some of this into practice before the end of gull season.
    Two of the most helpful references for Slaty-backed ID are Moores (2005) and Zimmer (2000):
    
    http://www.birdskorea.org/Birds/Identification/ID_Notes/BK-ID-Slaty-backed-Gull.shtml
    
    http://books.google.com/booksid=TMtB8CG767EC&pg=PA163&dq=Slaty-backed+Gull&hl=en&sa=X&ei=ywD3UqyYDoneoAS_3IHwBQ&ved=0CDMQ6AEwAA
    Probably the best way to familiarize yourself with this extremely variable bird, without going to Asia, is to spend some time on the Japanese Gull-Site:
    
    http://www23.tok2.com/home/jgull/gullidentifi_.htm
    
    Also be sure to read Chris Gibbins' excellent blog on this topic:
    
    http://chrisgibbins-gullsbirds.blogspot.com/2010/02/first-winter-slaty-backed-gull-bit-of.htmlm=1
    I highly recommend exploring the behavioral ecology work of Yutaka Watanuki on this species, which gives a bit of context for the phenotypic plasticity that has been at the root of our confusion as birders.
    
    Identifying birds in this cycle is not unlike identifying Accipiters. There are few cut-and-dried field marks, but with a little practice, we can learn to apply a whole suite of structural and plumage characters that make the identification of most individuals relatively clear. Admittedly, rampant hybridization forces us to let a higher percentage of gulls go, but that does not mean we should shy away from those birds displaying ten or twenty traits that add up to a reasonable conclusion.
    First, I should mention that the Arcata bird lacks deep pink legs. This is not uncommon on first-cycle Slaty-backed Gulls in Asia (see the Japanese Gull-Site).
    
    The following are 14 key traits of Slaty-backed (in no particular order) that differ from the Glaucous-winged/Herring continuum. Note that Slaty-backed is tremendously variable, and we should not expect all (any) birds to have ALL the "classic Slaty-backed" traits. I have added links to photos of the Arcata bird that illustrate these concepts.
    1) Short wings. This is often used by the Japanese experts.
    
    http://m.flickr.com/#/photos/101791769@N08/12314683794/
    
    Note that this species also seems to have exceptionally flexible wings. The humerus is often extended significantly. In combination with folding the secondaries inward, this can give the wings an unexpectedly long, narrow look:
    http://m.flickr.com/#/photos/101791769@N08/12267289063/
    
    2) The primary panel looks short and narrow, both on the sitting bird and in flight (except, of course, when the hand is fully spread). I have discussed this in a little more detail in the captions of these three photos:
    http://m.flickr.com/#/photos/101791769@N08/12314407293/
    
    http://www.flickr.com/photos/101791769@N08/12314260615/
    
    http://www.flickr.com/photos/101791769@N08/12272532173/
    
    3) Short, stout bill with minimal gonydeal angle and slightly drooping appearance:
    
    http://www.flickr.com/photos/101791769@N08/12314409633/
    
    4) Contrasting dark mask through the eye and onto the auriculars. Herring tends to be plainer on the face, while Glaucous-winged can have a dark smudge through the eye and onto the cap, and, sometimes, onto the auriculars. In the "classic Slaty-backed look", this dark mask is set off by a whitish half-collar on the side of the neck and a whitish area around the bill, as well as the rather bold eye crescents.
    http://m.flickr.com/#/photos/101791769@N08/12295002084/
    
    5) Plain-based greater coverts (dark brown when fresh, white later). This and all similar species have variable greater covert patterning, however.
    
    http://m.flickr.com/#/photos/101791769@N08/12294718133/
    
    6) Distinctly decurved gape, which is shared with California but generally not with Glaucous-winged or Herring. I have seen Glaucous-winged Gulls that approached this look, however.
    
    http://m.flickr.com/#/photos/101791769@N08/12402310734/in/photostream/
    
    7) Long mid-secondaries. These look like a point or bulge when spread, much like a skua. This is not obvious when they are more folded.
    
    http://m.flickr.com/#/photos/101791769@N08/12255374275/
    
    8) Contrastingly white background to rump. Many Slaty-backed Gulls have uncontrasting darker rumps, especially in fresh plumage. A contrastingly white background, however, is also common and differs from the darker rumps of both Glaucous-winged and American Herring gulls.
    http://m.flickr.com/#/photos/101791769@N08/12279690664/
    
    9) Many birds have a rather blocky-looking head shape, with a concave slope to the forehead. Glaucous-winged tends to have a more evenly rounded forehead (convex), while Herring has a rather flat-looking forehead. Conceivably, a hybrid might combine these two looks into something like Slaty-backed.
    http://m.flickr.com/#/photos/101791769@N08/12402147224/
    
    10) On many birds, the inner primaries are darker than either Glaucous-winged or Herring. The "shadow string of pearls" effect can be quite striking.
    
    http://m.flickr.com/#/photos/101791769@N08/12402310734/
    
    11) When resting and often while walking, Slaty-backed exhibits a very forward-hunched, pot-bellied, chest-heavy posture.
    
    http://m.flickr.com/#/photos/101791769@N08/12255795685/
    
    12) The legs of Slaty-backed vary from pale fleshy pink to dark, vivid pink. The latter is fairly distinctive, but note that low light angles can make any gull's feet look quite vivid.
    
    13) The legs vary greatly in length but are often notably widely-spaced, and the gait has been described as waddling or goose-like. A particularly thick-legged look is also characteristic but not always evident.
    
    http://m.flickr.com/#/photos/101791769@N08/12267708256/
    
    14) When alert, the neck looks very long. Other gulls can certainly approximate this look, however.
    
    http://m.flickr.com/#/photos/101791769@N08/12279614836/
    
    It is important to note that not all of these differences would apply to a Vega x Glaucous-winged hybrid. Therefore, it is crucial to confirm that dark brown extends to the base of the tail (though occasional apparent Slaty-backeds do have white mottling across the entire tail base; such a bird would likely be much more difficult to establish as a vagrant).
    Investigation of this formerly very popular identification problem seems to have dropped off drastically since I was a kid. This seems to stem from frustration with all the appearances presented by the prevalent hybrids in this state. Nonetheless, working out these issues has very much been a community effort, and I hope that continues; I would love to hear more discussion and debate on this matter. I'd particularly like to thank Zachary Ormsby, John Sterling, Ken Burton, Alvaro Jaramillo, Steve Hampton, Peter Pyle, Jude Claire Power, David Fix, Osao and Michiaki Ujihara, Rob Fowler, Amar Ayyash, Paul Lehman, Steve Howell, Martin Meyers, and Steve Rottenborn for joining me in grappling with this problem over the course of the winter.
    Go find some county first Slaty-backed Gulls!
    
    Tristan McKee
    Arcata, CA
    
    -- Steve HamptonDavis, CA
    
    
  24. -back to top-
  25. Cook Inlet vs. Slaty-backed: a summary LINK
    DATE: Feb 9, 2014 @ 2:42am, 4 year(s) ago
    Hi Calbirders,
    
    Regardless of its identification, the juvenile gull frequenting downtown Arcata this winter provides an unparalleled opportunity to ponder Slaty-backed characters up close, in direct comparison with Glaucous-winged and Herring gulls and their apparent hybrids. These hybrids are the source of the popular notion that first-cycle Slaty-backed Gulls simply cannot be identified here, in the absence of incoming slaty mantle feathers. However, the Arcata bird shows numerous traits that differ from both species and are not intermediate between them. I have also just uploaded a zoomed-in photo that shows an incoming bluish-slate-colored mantle feather (I am unsure if this is diagnostic, so I'm not placing much weight on it at this point):
    
    http://m.flickr.com/#/photos/101791769@N08/12394547043/
    
    Since development of identification criteria for this cycle has largely occurred on the internet and is widely scattered, I have summarized the results of my work this winter to distinguish Slaty-backed from "Cook Inlet" hybrids. A more detailed account will be published shortly, but I figured hey, it's February, and there is still time to put some of this into practice before the end of gull season.
    
    Two of the most helpful references for Slaty-backed ID are Moores (2005) and Zimmer (2000):
    
    http://www.birdskorea.org/Birds/Identification/ID_Notes/BK-ID-Slaty-backed-Gull.shtml
    
    http://books.google.com/booksid=TMtB8CG767EC&pg=PA163&dq=Slaty-backed+Gull&hl=en&sa=X&ei=ywD3UqyYDoneoAS_3IHwBQ&ved=0CDMQ6AEwAA
    
    Probably the best way to familiarize yourself with this extremely variable bird, without going to Asia, is to spend some time on the Japanese Gull-Site:
    
    http://www23.tok2.com/home/jgull/gullidentifi_.htm
    
    Also be sure to read Chris Gibbins' excellent blog on this topic:
    
    http://chrisgibbins-gullsbirds.blogspot.com/2010/02/first-winter-slaty-backed-gull-bit-of.htmlm=1
    
    I highly recommend exploring the behavioral ecology work of Yutaka Watanuki on this species, which gives a bit of context for the phenotypic plasticity that has been at the root of our confusion as birders.
    
    Identifying birds in this cycle is not unlike identifying Accipiters. There are few cut-and-dried field marks, but with a little practice, we can learn to apply a whole suite of structural and plumage characters that make the identification of most individuals relatively clear. Admittedly, rampant hybridization forces us to let a higher percentage of gulls go, but that does not mean we should shy away from those birds displaying ten or twenty traits that add up to a reasonable conclusion.
    
    First, I should mention that the Arcata bird lacks deep pink legs. This is not uncommon on first-cycle Slaty-backed Gulls in Asia (see the Japanese Gull-Site).
    
    The following are 14 key traits of Slaty-backed (in no particular order) that differ from the Glaucous-winged/Herring continuum. Note that Slaty-backed is tremendously variable, and we should not expect all (any) birds to have ALL the "classic Slaty-backed" traits. I have added links to photos of the Arcata bird that illustrate these concepts.
    
    1) Short wings. This is often used by the Japanese experts.
    
    http://m.flickr.com/#/photos/101791769@N08/12314683794/
    
    Note that this species also seems to have exceptionally flexible wings. The humerus is often extended significantly. In combination with folding the secondaries inward, this can give the wings an unexpectedly long, narrow look:
    
    http://m.flickr.com/#/photos/101791769@N08/12267289063/
    
    2) The primary panel looks short and narrow, both on the sitting bird and in flight (except, of course, when the hand is fully spread). I have discussed this in a little more detail in the captions of these three photos:
    
    http://m.flickr.com/#/photos/101791769@N08/12314407293/
    
    http://www.flickr.com/photos/101791769@N08/12314260615/
    
    http://www.flickr.com/photos/101791769@N08/12272532173/
    
    3) Short, stout bill with minimal gonydeal angle and slightly drooping appearance:
    
    http://www.flickr.com/photos/101791769@N08/12314409633/
    
    4) Contrasting dark mask through the eye and onto the auriculars. Herring tends to be plainer on the face, while Glaucous-winged can have a dark smudge through the eye and onto the cap, and, sometimes, onto the auriculars. In the "classic Slaty-backed look", this dark mask is set off by a whitish half-collar on the side of the neck and a whitish area around the bill, as well as the rather bold eye crescents.
    
    http://m.flickr.com/#/photos/101791769@N08/12295002084/
    
    5) Plain-based greater coverts (dark brown when fresh, white later). This and all similar species have variable greater covert patterning, however.
    
    http://m.flickr.com/#/photos/101791769@N08/12294718133/
    
    6) Distinctly decurved gape, which is shared with California but generally not with Glaucous-winged or Herring. I have seen Glaucous-winged Gulls that approached this look, however.
    
    http://m.flickr.com/#/photos/101791769@N08/12402310734/in/photostream/
    
    7) Long mid-secondaries. These look like a point or bulge when spread, much like a skua. This is not obvious when they are more folded.
    
    http://m.flickr.com/#/photos/101791769@N08/12255374275/
    
    8) Contrastingly white background to rump. Many Slaty-backed Gulls have uncontrasting darker rumps, especially in fresh plumage. A contrastingly white background, however, is also common and differs from the darker rumps of both Glaucous-winged and American Herring gulls.
    
    http://m.flickr.com/#/photos/101791769@N08/12279690664/
    
    9) Many birds have a rather blocky-looking head shape, with a concave slope to the forehead. Glaucous-winged tends to have a more evenly rounded forehead (convex), while Herring has a rather flat-looking forehead. Conceivably, a hybrid might combine these two looks into something like Slaty-backed.
    
    http://m.flickr.com/#/photos/101791769@N08/12402147224/
    
    10) On many birds, the inner primaries are darker than either Glaucous-winged or Herring. The "shadow string of pearls" effect can be quite striking.
    
    http://m.flickr.com/#/photos/101791769@N08/12402310734/
    
    11) When resting and often while walking, Slaty-backed exhibits a very forward-hunched, pot-bellied, chest-heavy posture.
    
    http://m.flickr.com/#/photos/101791769@N08/12255795685/
    
    12) The legs of Slaty-backed vary from pale fleshy pink to dark, vivid pink. The latter is fairly distinctive, but note that low light angles can make any gull's feet look quite vivid.
    
    13) The legs vary greatly in length but are often notably widely-spaced, and the gait has been described as waddling or goose-like. A particularly thick-legged look is also characteristic but not always evident.
    
    http://m.flickr.com/#/photos/101791769@N08/12267708256/
    
    14) When alert, the neck looks very long. Other gulls can certainly approximate this look, however.
    
    http://m.flickr.com/#/photos/101791769@N08/12279614836/
    
    It is important to note that not all of these differences would apply to a Vega x Glaucous-winged hybrid. Therefore, it is crucial to confirm that dark brown extends to the base of the tail (though occasional apparent Slaty-backeds do have white mottling across the entire tail base; such a bird would likely be much more difficult to establish as a vagrant).
    
    Investigation of this formerly very popular identification problem seems to have dropped off drastically since I was a kid. This seems to stem from frustration with all the appearances presented by the prevalent hybrids in this state. Nonetheless, working out these issues has very much been a community effort, and I hope that continues; I would love to hear more discussion and debate on this matter. I'd particularly like to thank Zachary Ormsby, John Sterling, Ken Burton, Alvaro Jaramillo, Steve Hampton, Peter Pyle, Jude Claire Power, David Fix, Osao and Michiaki Ujihara, Rob Fowler, Amar Ayyash, Paul Lehman, Steve Howell, Martin Meyers, and Steve Rottenborn for joining me in grappling with this problem over the course of the winter.
    
    Go find some county first Slaty-backed Gulls!
    
    Tristan McKee
    Arcata, CA
    
    
  26. -back to top-
  27. First-cycle Slaty-backed Gull LINK
    DATE: Jan 26, 2014 @ 3:53am, 4 year(s) ago
    Calbirders,
    
    Comprised of only a few hundred individuals at a time, the gull flock at Redwood Creek Mouth, Orick, Humboldt County, is nontheless extremely varied. These digiscoped images and video stills, while fuzzy, still show quite a number of key characters of a first-cycle Slaty-backed Gull on 25 January 2014:
    
    http://www.flickr.com/photos/101791769@N08/
    
    1) Shadow string of pearls, with pale concentrated at the bases of the central primaries, rather than on the inner primaries, as is Herring (described by Pyle in 1997, Birders Journal).
    
    2) Short wings with distinctly convex trailing edges to primaries and secondaries, and small, rounded "hand".
    
    On the standing bird, note:
    
    3) Blocky head and short, stout, slightly downward-angled bill.
    
    4) Foreward-hunched posture (resting) with long neck (alert) and bulging chest.
    
    5) Plain-centered greater coverts and tertials.
    
    6) Short, narrow primary panel with nonetheless broad-tipped individual primaries.
    
    Although this species is often thought to retain a dark bill until late winter, I have seen numerous photos of October-December juveniles with bills like this is Japan.
    
    Rob Fowler and I are going to return today with real cameras, so check back this evening for hopefully better shots.
    
    Good gulling,
    Tristan McKee
    Arcata, CA
    
    
  28. -back to top-
  29. Slaty-backed Gull - Half Moon Bay LINK
    DATE: Jan 9, 2014 @ 2:26pm, 5 year(s) ago
    Folks,
    
    There was a third cycle Slaty-backed Gull at the mouth of Pilarcitos Creek (Venice Beach) in Half Moon Bay, Sn. Mateo Co. today. I was looking at the flock for well over an hour until I spotted this one, it is not obvious as some have been in the past. Photos here: http://www.flickr.com/photos/alvarojaramillo/11861782556/
    
    Good birding,
    
    Alvaro
    
    Alvaro Jaramillo
    alvaro@...
    www.alvarosadventures.com
    
    
  30. -back to top-


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