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Possible Manx Shearwater off of Mugu Rock

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  • Steve Sosensky
    Hi All, This morning I did a sea watch from Mugu Rock on Pacific Coast Hwy. in Vertura Co. from 0730 to 0900. There was a flock of Black-vented Shearwaters
    Message 1 of 3 , Mar 3 7:46 PM
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      Hi All,

      This morning I did a sea watch from Mugu Rock on Pacific Coast Hwy. in
      Vertura Co. from 0730 to 0900. There was a flock of Black-vented
      Shearwaters about 300 to 500 yards off shore. I viewed them with my scope
      at 60x. In this flock was one Shearwater, about the same size, shape, and
      color as the BVs, which had a white vent. Though I would have liked better,
      longer, and closer looks, I think this was a Manx Shearwater.

      Also in the area were one or two Black-legged Kittiwakes and an adult male
      Black Scoter, the latter being much closer in.


      Good birding,
      Steve <mailto:steve@...> for general use
      <mailto:mobile@...> for rare birds and emergencies only

      Steve Sosensky, photographer www.sosensky.com
      10834 Blix Street #213 818-508-4946
      Toluca Lake, CA 91602 34*09'02" N, 118*22'47" W
      Audubon in So. California www.SoCalAudubon.org/socal/
      San Fernando Valley AS www.SanFernandoValleyAudubon.org/sfvas/
      AIM ID: SteveS310 Yahoo Messenger ID: SteveSosensky
      SoCal FRS: use channel 11 code 22
    • toddamcgrath
      ... Hwy. in ... my scope ... shape, and ... liked better, ... I wanted to point out a couple of things about Manx vs Black-vented Shearwater. First, vent color
      Message 2 of 3 , Mar 3 8:50 PM
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        --- In CALBIRDS@y..., Steve Sosensky <Steve@S...> wrote:
        > Hi All,
        >
        > This morning I did a sea watch from Mugu Rock on Pacific Coast
        Hwy. in
        > Vertura Co. from 0730 to 0900. There was a flock of Black-vented
        > Shearwaters about 300 to 500 yards off shore. I viewed them with
        my scope
        > at 60x. In this flock was one Shearwater, about the same size,
        shape, and
        > color as the BVs, which had a white vent. Though I would have
        liked better,
        > longer, and closer looks, I think this was a Manx Shearwater.

        I wanted to point out a couple of things about Manx vs Black-vented
        Shearwater. First, vent color is not completely reliable as a mark.
        Don Roberson wrote an excellent article in Birding a few years back,
        and had a photo of a black-vented shearwater with a white undertail.
        (I would provide a cite, but am away from my library at the moment.)
        Upon close inspection, the bird showed a creamy white undertail,
        with some darker smudges. I was on the boat when those photos were
        taken in Monterey, and have since seen a couple of others. It was
        never difficult to separate these birds from Manx, as they appear
        noticeably different due to the brownish color, creamy rather than
        white underparts, and the lack of strong demarcation between the
        black and White.

        In flight Manx is much darker than black-vented and clearly
        demarcated, a sharp black and white, as opposed to brown and smudgy.
        In flight, Manx often shows small white ovals at the sides of the
        rump, and appears a much cleaner white underneath.

        On the water, Manx shows clean white on the sides and flanks, as
        well as a very dark back, and usually some white in the ariculars.
        when looking for Manx shearwater on the water, it is more difficult
        to distinguish it from Buller's Shearwater than Black-vented,
        especially if the birds are facing away from you.

        If the bird at Pt Mugu was close enough to observe vent color, but
        appeared in other respects similar to Black-vented, I would find it
        difficult to rule out one of the "white-vented" Black-vented
        Shearwaters, as the bird should have stood out in several other
        respects, as I noted above.

        Todd McGrath
        SKUA@...
        Marina Del Rey CA
      • Steve Sosensky
        Todd and CalBirders, Thanks for your comments. As I said, I didn t have very long looks, and only really noticed the underside of the bird the couple of times
        Message 3 of 3 , Mar 3 11:15 PM
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          Todd and CalBirders,

          Thanks for your comments. As I said, I didn't have very long looks, and
          only really noticed the underside of the bird the couple of times I saw it.
          Unfortunately, I'm not familiar with Don Roberson's paper (I'd love a copy
          if you find it or Don is reading this email), and my field guides don't
          show a difference in the color of the upper parts. So, I appreciate any help.

          The thing that did stand out for me when seeing the bird was the brilliance
          of the white on the belly, vent, and wings, but that and the size are the
          only field marks I can attest to. That's why I said "possible". I'd
          appreciate if Todd or any others with more experience with separating Manx
          and BV Shearwaters could go out and look.

          At 04:50 AM 2002-03-04 +0000, toddamcgrath wrote:
          >--- In CALBIRDS@y..., Steve Sosensky <Steve@S...> wrote:
          > > Hi All,
          > >
          > > This morning I did a sea watch from Mugu Rock on Pacific Coast Hwy. in
          > > Vertura Co. from 0730 to 0900. There was a flock of Black-vented
          > > Shearwaters about 300 to 500 yards off shore. I viewed them with my scope
          > > at 60x. In this flock was one Shearwater, about the same size, shape, and
          > > color as the BVs, which had a white vent. Though I would have liked
          > better,
          > > longer, and closer looks, I think this was a Manx Shearwater.
          >
          >I wanted to point out a couple of things about Manx vs Black-vented
          >Shearwater. First, vent color is not completely reliable as a mark. Don
          >Roberson wrote an excellent article in Birding a few years back, and had a
          >photo of a black-vented shearwater with a white undertail... Upon close
          >inspection, the bird showed a creamy white undertail, with some darker
          >smudges. ... It was never difficult to separate these birds from Manx, as
          >they appear noticeably different due to the brownish color, creamy rather
          >than white underparts, and the lack of strong demarcation between the
          >black and White.
          >
          >In flight Manx is much darker than black-vented and clearly demarcated, a
          >sharp black and white, as opposed to brown and smudgy. In flight, Manx
          >often shows small white ovals at the sides of the
          >rump, and appears a much cleaner white underneath.
          >
          >If the bird at Pt Mugu was close enough to observe vent color, but
          >appeared in other respects similar to Black-vented, I would find it
          >difficult to rule out one of the "white-vented" Black-vented Shearwaters,
          >as the bird should have stood out in several other respects, as I noted above.

          Good birding,
          Steve <mailto:steve@...> for general use
          <mailto:mobile@...> for rare birds and emergencies only

          Steve Sosensky, photographer www.sosensky.com
          10834 Blix Street #213 818-508-4946
          Toluca Lake, CA 91602 34*09'02" N, 118*22'47" W
          Audubon in So. California www.SoCalAudubon.org/socal/
          San Fernando Valley AS www.SanFernandoValleyAudubon.org/sfvas/
          AIM ID: SteveS310 Yahoo Messenger ID: SteveSosensky
          SoCal FRS: use channel 11 code 22
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