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feather structure

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  • Recio Joaquin
    Hi everybody, Probably this is a stupid question .... but I can not find the answer. Why the same feather appears green in the outer part and grey in the inner
    Message 1 of 5 , Mar 2, 2013
      Hi everybody,

      Probably this is a stupid question .... but I can not find the answer.
      Why the same feather appears green in the outer part and grey in the
      inner part? Is there a different deposition of psittacofulvines in the
      feather cortex depending on outer/inner part of the feather? ... and
      what about the effect of the spongy zone to get blues ... does it exist
      the spongy zone in the inner part of the feathers? Is feather structure
      different depending on the the outer/inner part considered?

      Something else: in Ara araucana the inner part of the blue remiges
      appears as a golden yellow brigth colour with some kind of iridescence
      while the outer part is blue. The golden colour of the inner part seems
      to be some kind of structural yellow. Do you know of any parrot
      species/mutations showing a yellow structural colour?

      Regards

      Recio
    • Peter Wouters
      Hi Recio, In Kakariki the amount of psittacofulvins and eumelanin can vary in the same feather. In Lutino’s a feather may appear light Yellow in the centre
      Message 2 of 5 , Mar 3, 2013
        Hi Recio,
         
        In Kakariki the amount of psittacofulvins and eumelanin can vary in the same feather. In Lutino’s a feather may appear light Yellow in the centre and deeper Yellow in the outer part. Others may have an even Yellow feather. This counts also for Eumelanin deposit. It al depends on the individual. The entire bird can vary natural. Normals can vary from bright Green to a slight Olive Green.
         
        Why the same feather appears green in the outer part and grey in the
        inner part?
         
        Probably this is a (structural) feather with a lesser deposit of psittacofulvins (or even a change in Yellow/Red ratio) combined with some degree of foreground melanin in the centre?
         
        Regards
        Peter
         
        Sent: Saturday, March 02, 2013 7:29 PM
        Subject: [Genetics-Psittacine] feather structure
         
         


        Hi everybody,

        Probably this is a stupid question .... but I can not find the answer.
        Why the same feather appears green in the outer part and grey in the
        inner part? Is there a different deposition of psittacofulvines in the
        feather cortex depending on outer/inner part of the feather? ... and
        what about the effect of the spongy zone to get blues ... does it exist
        the spongy zone in the inner part of the feathers? Is feather structure
        different depending on the the outer/inner part considered?

        Something else: in Ara araucana the inner part of the blue remiges
        appears as a golden yellow brigth colour with some kind of iridescence
        while the outer part is blue. The golden colour of the inner part seems
        to be some kind of structural yellow. Do you know of any parrot
        species/mutations showing a yellow structural colour?

        Regards

        Recio

      • Terry Martin
        Recio Grey parts of feathers merely lack the necessary structure for constructive interference in those regions. Generally, since only certain parts of the
        Message 3 of 5 , Mar 10, 2013
          Recio

          Grey parts of feathers merely lack the necessary structure for constructive
          interference in those regions. Generally, since only certain parts of the
          feather are visible when carried normally on the body, it is only those
          visible portions that have selection pressure for special plumage
          colourations. Some feathers will have zones of altered colour that can be
          displayed by the bird. But generally the 'lower' portions of feathers on
          most species lack structural colour and carry only melanin and hence appear
          grey.

          I have not read of any form of structural yellow colour in birds.

          Terry

          -----Original Message-----
          From: Recio Joaquin
          Sent: Sunday, March 03, 2013 4:29 AM
          To: Genetics-Psittacine@yahoogroups.com
          Subject: [Genetics-Psittacine] feather structure


          Hi everybody,

          Probably this is a stupid question .... but I can not find the answer.
          Why the same feather appears green in the outer part and grey in the
          inner part? Is there a different deposition of psittacofulvines in the
          feather cortex depending on outer/inner part of the feather? ... and
          what about the effect of the spongy zone to get blues ... does it exist
          the spongy zone in the inner part of the feathers? Is feather structure
          different depending on the the outer/inner part considered?

          Something else: in Ara araucana the inner part of the blue remiges
          appears as a golden yellow brigth colour with some kind of iridescence
          while the outer part is blue. The golden colour of the inner part seems
          to be some kind of structural yellow. Do you know of any parrot
          species/mutations showing a yellow structural colour?

          Regards

          Recio








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        • Recio Joaquin
          Hi Peter,   I was not refering to the external or edge part of the feather but to the outer side versus inner side. The inner side appears very often as grey,
          Message 4 of 5 , Mar 11, 2013
            Hi Peter,
             
            I was not refering to the external or edge part of the feather but to the outer side versus inner side. The inner side appears very often as grey, without the constructive interference effect. Feather barbs/barbules structure is classically represented by the Dirk van den Abeele graphics (http://www.agapornis.be/veder1.htm) and this graphic shows an homogeneous structure of the barbule independently of considering the inner or the outer side. If I am not wrong a single barbule dysplays one side to the external side of the feather and another one to the inner side ... so the barbule structure should be represented differently if there is a different microscopic structure affecting each side.
             
            Regards
             
            Recio

            From: Peter Wouters <wouterscalant@...>
            To: Genetics-Psittacine@yahoogroups.com
            Sent: Sunday, March 3, 2013 1:39 PM
            Subject: Re: [Genetics-Psittacine] feather structure
             
            Hi Recio,
             
            In Kakariki the amount of psittacofulvins and eumelanin can vary in the same feather. In Lutino’s a feather may appear light Yellow in the centre and deeper Yellow in the outer part. Others may have an even Yellow feather. This counts also for Eumelanin deposit. It al depends on the individual. The entire bird can vary natural. Normals can vary from bright Green to a slight Olive Green.
             
            Why the same feather appears green in the outer part and grey in the
            inner part?
             
            Probably this is a (structural) feather with a lesser deposit of psittacofulvins (or even a change in Yellow/Red ratio) combined with some degree of foreground melanin in the centre?
             
            Regards
            Peter
             
            Sent: Saturday, March 02, 2013 7:29 PM
            Subject: [Genetics-Psittacine] feather structure
             
             

            Hi everybody,

            Probably this is a stupid question .... but I can not find the answer.
            Why the same feather appears green in the outer part and grey in the
            inner part? Is there a different deposition of psittacofulvines in the
            feather cortex depending on outer/inner part of the feather? ... and
            what about the effect of the spongy zone to get blues ... does it exist
            the spongy zone in the inner part of the feathers? Is feather structure
            different depending on the the outer/inner part considered?

            Something else: in Ara araucana the inner part of the blue remiges
            appears as a golden yellow brigth colour with some kind of iridescence
            while the outer part is blue. The golden colour of the inner part seems
            to be some kind of structural yellow. Do you know of any parrot
            species/mutations showing a yellow structural colour?

            Regards

            Recio

          • Recio Joaquin
            Hi Terry,   I own a blue feather that my son took two years ago when visiting Loro Parque in the Canary Islands (Spain). The feather was besides a big
            Message 5 of 5 , Mar 11, 2013
              Hi Terry,
               
              I own a blue feather that my son took two years ago when visiting Loro Parque in the Canary Islands (Spain). The feather was besides a big aviary with Ara araucanas and thus I think it belongs to this species. The external side is completelly blue and the inner part shows a brillant golden colour. I have some reasons to think that this is a structural yellow:
              1. It is iridiscent ... alteration of feather structure (maybe similar to Misty?)
              2. It is not fluorescent under uv (if it was fluorescent it would mean that fluorescent psittacins were there).
              3. The outer side is blue. If there were psittacins I would have expected the outer side to be green.
              4. Colour distribution is homogeneous along the feather. We know that usually the amount of psittacins is not uniphorm within one feather, expressing higher concentrations at the tip of the feather, on the part which is exposed and seen by the other bird partners.
               
              I will take some pics next week-end of both sides of the feather, before and after hitting it with a hammer to destroy the structure and find out if the golden yellow, as well as the blue colour, disappears and "confirms" the existence of structural yellow in parrots.
               
              Do you know if there are confirmed structural mutations mainly affecting the feather cortex? ... and of any other structural colour than blue and its family (dark, violet, deep?)
               
              Regards
               
              Recio

              From: Terry Martin <sbankvet@...>
              To: Genetics-Psittacine@yahoogroups.com
              Sent: Monday, March 11, 2013 2:20 AM
              Subject: Re: [Genetics-Psittacine] feather structure
               
              Recio

              Grey parts of feathers merely lack the necessary structure for constructive
              interference in those regions. Generally, since only certain parts of the
              feather are visible when carried normally on the body, it is only those
              visible portions that have selection pressure for special plumage
              colourations. Some feathers will have zones of altered colour that can be
              displayed by the bird. But generally the 'lower' portions of feathers on
              most species lack structural colour and carry only melanin and hence appear
              grey.

              I have not read of any form of structural yellow colour in birds.

              Terry

              -----Original Message-----
              From: Recio Joaquin
              Sent: Sunday, March 03, 2013 4:29 AM
              To: mailto:Genetics-Psittacine%40yahoogroups.com
              Subject: [Genetics-Psittacine] feather structure

              Hi everybody,

              Probably this is a stupid question .... but I can not find the answer.
              Why the same feather appears green in the outer part and grey in the
              inner part? Is there a different deposition of psittacofulvines in the
              feather cortex depending on outer/inner part of the feather? ... and
              what about the effect of the spongy zone to get blues ... does it exist
              the spongy zone in the inner part of the feathers? Is feather structure
              different depending on the the outer/inner part considered?

              Something else: in Ara araucana the inner part of the blue remiges
              appears as a golden yellow brigth colour with some kind of iridescence
              while the outer part is blue. The golden colour of the inner part seems
              to be some kind of structural yellow. Do you know of any parrot
              species/mutations showing a yellow structural colour?

              Regards

              Recio

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