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Flam Owl, Broad-tailed Hummingbird, and Grace's Warbler

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  • Brenda Wright
    Greetings, Finally I have a few days off so am making a few comments pertaining to some past e-mails. Broad-tailed Hummingbird; We have them at our feeder this
    Message 1 of 3 , Jun 21, 2006
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      Greetings,
      Finally I have a few days off so am making a few
      comments pertaining to some past e-mails.
      Broad-tailed Hummingbird; We have them at our feeder
      this summer which is unusual. They migrated late and
      some just never moved up to higher elevation.
      What I really found interesting was in the ponderosa
      pine report Rich Levad sent to the wsbn. Broad-tails
      were listed as the most dense species and no other
      species were really contenders. Broad-tailed
      Hummingbirds had a density of 162.33 birds/km2.
      Number two was Gray-headed Junco at 97.42. From my
      experience I think I think can challenge that info a
      bit. Broad-tails are detected(males) by wing noise.
      Observers(some and maybe most) don't detect BTLH
      unless they are quite close. BTLH also seem to check
      out observers(especially those who wear something
      colorful) and fly in close. I know I am guilty in the
      detection department. I rarely detect more than two
      or three BTLH per ponderosa transect but they are
      mostly at very close range(two or three meters). Data
      for birds detected at close range has a major impact
      on inflating density.
      Another mystery has been my inability to find BTLH in
      Mexico. BTLH winter in the central volcanic belt
      where I have spent a good deal of time four different
      winters. We(several birders in our group) have only
      seen a few females or immature hummers). Where are
      the adult males? A good population of BTLH nest in
      Sonora and Coahuila where they are considered a fairly
      common breeder.

      What is happening with Grace's Warblers? I worked one
      ponderose transect northeast of Nucla. On this
      transect of 15 points I detected 20 singing male
      Grace's Warblers. The habitat is very good with a
      great Gambel's Oak understory. I can remember 20 years
      ago we would search for several hours just to find a
      single Grace's in about the same place.

      Maybe the answer is lies in Rich, Mike, and Kenny's
      Flammulated Owling work. Do we have more owls? Maybe
      Arizona and New Mexico FLOWs are coming up here. If so
      maybe other species are coming north also, like
      Grace's Warbler and how about Hood Orioles.

      I think a better explanation lies in the ingenious
      nature of point counts. It is a very powerful tool to
      find birds. In the past we would drive around and play
      a tape here and there without a plan. Same thing with
      GRWA. We would look for birds in several places but
      most certainly did not cover the ground a point count
      does.
      When point counts are done to protocol this info will
      establish a base to draw on in the future. At this
      juncture in time we really don't have much to go on
      historically. I guess all these unanswered questions
      is what makes the natural world so interesting to me.
      Coen

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    • levad
      Hi, A caveat needs to be added to the use of bird densities arrived at through point-counts. Coen hinted at it with hid BTLH illustration. There are a number
      Message 2 of 3 , Jun 21, 2006
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        Hi,

        A caveat needs to be added to the use of bird densities arrived at through point-counts.  Coen hinted at it with hid BTLH illustration.  There are a number of factors--including behaviors like those Coen described--that make detection probabilities vastly different from species to species.  These diferences affect the density estimates derived, so such figures are useful only in comparing figures WITHIN a species (e.g BTLH densities in different habitats, regions, or years) and comparing density figures BETWEEN species can be entertaining and suggestive, BUT misleading.   The density figure is an index to population dyamics of a species, but may have little relationship to the bird's actual density on the ground.

        Rich


        From: Brenda Wright <coenbrenda@...>
        Sent: Wednesday, June 21, 2006 7:30 PM
        To: wsbn wsbn <wsbn@yahoogroups.com>
        Subject: [wsbn] Flam Owl, Broad-tailed Hummingbird, and Grace's Warbler


        Greetings,
        Finally I have a few days off so am making a few
        comments pertaining to some past e-mails.
        Broad-tailed Hummingbird; We have them at our feeder
        this summer which is unusual. They migrated late and
        some just never moved up to higher elevation.
        What I really found interesting was in the ponderosa
        pine report Rich Levad sent to the wsbn. Broad-tails
        were listed as the most dense species and no other
        species were really contenders. Broad-tailed
        Hummingbirds had a density of 162.33 birds/km2.
        Number two was Gray-headed Junco at 97.42. From my
        experience I think I think can challenge that info a
        bit. Broad-tails are detected(males) by wing noise.
        Observers(some and maybe most) don't detect BTLH
        unless they are quite close. BTLH also seem to check
        out observers(especially those who wear something
        colorful) and fly in close. I know I am guilty in the
        detection department. I rarely detect more than two
        or three BTLH per ponderosa transect but they are
        mostly at very close range(two or three meters). Data
        for birds detected at close range has a major impact
        on inflating density.
        Another mystery has been my inability to find BTLH in
        Mexico. BTLH winter in the central volcanic belt
        where I have spent a good deal of time four different
        winters. We(several birders in our group) have only
        seen a few females or immature hummers). Where are
        the adult males? A good population of BTLH nest in
        Sonora and Coahuila where they are considered a fairly
        common breeder.

        What is happening with Grace's Warblers? I worked one
        ponderose transect northeast of Nucla. On this
        transect of 15 points I detected 20 singing male
        Grace's Warblers. The habitat is very good with a
        great Gambel's Oak understory. I can remember 20 years
        ago we would search for several hours just to find a
        single Grace's in about the same place.

        Maybe the answer is lies in Rich, Mike, and Kenny's
        Flammulated Owling work. Do we have more owls? Maybe
        Arizona and New Mexico FLOWs are coming up here. If so
        maybe other species are coming north also, like
        Grace's Warbler and how about Hood Orioles.

        I think a better explanation lies in the ingenious
        nature of point counts. It is a very powerful tool to
        find birds. In the past we would drive around and play
        a tape here and there without a plan. Same thing with
        GRWA. We would look for birds in several places but
        most certainly did not cover the ground a point count
        does.
        When point counts are done to protocol this info will
        establish a base to draw on in the future. At this
        juncture in time we really don't have much to go on
        historically. I guess all these unanswered questions
        is what makes the natural world so interesting to me.
        Coen

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      • levad
        Hi, A caveat needs to be added to the use of bird densities arrived at through point-counts. Coen hinted at it with hid BTLH illustration. There are a number
        Message 3 of 3 , Jun 21, 2006
        • 0 Attachment
          Hi,

          A caveat needs to be added to the use of bird densities arrived at through point-counts.  Coen hinted at it with hid BTLH illustration.  There are a number of factors--including behaviors like those Coen described--that make detection probabilities vastly different from species to species.  These diferences affect the density estimates derived, so such figures are useful only in comparing figures WITHIN a species (e.g BTLH densities in different habitats, regions, or years) and comparing density figures BETWEEN species can be entertaining and suggestive, BUT misleading.   The density figure is an index to population dyamics of a species, but may have little relationship to the bird's actual density on the ground.

          Rich


          From: Brenda Wright <coenbrenda@...>
          Sent: Wednesday, June 21, 2006 7:30 PM
          To: wsbn wsbn <wsbn@yahoogroups.com>
          Subject: [wsbn] Flam Owl, Broad-tailed Hummingbird, and Grace's Warbler


          Greetings,
          Finally I have a few days off so am making a few
          comments pertaining to some past e-mails.
          Broad-tailed Hummingbird; We have them at our feeder
          this summer which is unusual. They migrated late and
          some just never moved up to higher elevation.
          What I really found interesting was in the ponderosa
          pine report Rich Levad sent to the wsbn. Broad-tails
          were listed as the most dense species and no other
          species were really contenders. Broad-tailed
          Hummingbirds had a density of 162.33 birds/km2.
          Number two was Gray-headed Junco at 97.42. From my
          experience I think I think can challenge that info a
          bit. Broad-tails are detected(males) by wing noise.
          Observers(some and maybe most) don't detect BTLH
          unless they are quite close. BTLH also seem to check
          out observers(especially those who wear something
          colorful) and fly in close. I know I am guilty in the
          detection department. I rarely detect more than two
          or three BTLH per ponderosa transect but they are
          mostly at very close range(two or three meters). Data
          for birds detected at close range has a major impact
          on inflating density.
          Another mystery has been my inability to find BTLH in
          Mexico. BTLH winter in the central volcanic belt
          where I have spent a good deal of time four different
          winters. We(several birders in our group) have only
          seen a few females or immature hummers). Where are
          the adult males? A good population of BTLH nest in
          Sonora and Coahuila where they are considered a fairly
          common breeder.

          What is happening with Grace's Warblers? I worked one
          ponderose transect northeast of Nucla. On this
          transect of 15 points I detected 20 singing male
          Grace's Warblers. The habitat is very good with a
          great Gambel's Oak understory. I can remember 20 years
          ago we would search for several hours just to find a
          single Grace's in about the same place.

          Maybe the answer is lies in Rich, Mike, and Kenny's
          Flammulated Owling work. Do we have more owls? Maybe
          Arizona and New Mexico FLOWs are coming up here. If so
          maybe other species are coming north also, like
          Grace's Warbler and how about Hood Orioles.

          I think a better explanation lies in the ingenious
          nature of point counts. It is a very powerful tool to
          find birds. In the past we would drive around and play
          a tape here and there without a plan. Same thing with
          GRWA. We would look for birds in several places but
          most certainly did not cover the ground a point count
          does.
          When point counts are done to protocol this info will
          establish a base to draw on in the future. At this
          juncture in time we really don't have much to go on
          historically. I guess all these unanswered questions
          is what makes the natural world so interesting to me.
          Coen

          __________________________________________________
          Do You Yahoo!?
          Tired of spam? Yahoo! Mail has the best spam protection around
          http://mail.yahoo.com


          ------------------------ Yahoo! Groups Sponsor --------------------~-->
          Check out the new improvements in Yahoo! Groups email.
          http://us.click.yahoo.com/6pRQfA/fOaOAA/yQLSAA/70TolB/TM
          --------------------------------------------------------------------~->


          Yahoo! Groups Links

          <*> To visit your group on the web, go to:
          http://groups.yahoo.com/group/wsbn/

          <*> To unsubscribe from this group, send an email to:
          wsbn-unsubscribe@yahoogroups.com

          <*> Your use of Yahoo! Groups is subject to:
          http://docs.yahoo.com/info/terms/





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