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Y Grosbeak bill shape thoughts

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  • Thomas Miko
    Hi Calbirders, Before I say what I am going to say, please let me say this: I am not a field biologist or an ornithologist, just a birder. I work with
    Message 1 of 2 , Aug 4, 2006
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      Hi Calbirders,

      Before I say what I am going to say, please let me say this: I am not a field biologist or an ornithologist, just a birder. I work with radioactive drugs.


      Okay, caveat's over. Here's what I have been up to: This whole allegation that the Albuequerque and the Big Pine Yellow Grosbeaks are Tijuana Specials i.e. escaped cage birds is killing me, especially since to me the bill is not misshapen, just misproportioned. I have written to some people in central Mexico (seeking their expertise on Yellow Grosbeaks) in bad Spanish, and haven't heard back. I also wrote to someone in Alaska who is working on bill deformities. Links to all will be below. Here's the thing that struck me: The Tucson bird had "the right bill shape", but it was a full adult. Our bird and the New Mexico bird were immature males. So, how do we not know through our collective lack of experience with central Mexican birds on their home turf that it is totally normal for the immature birds to look like this, and only the adult males have the bill shape that we see on the Tucson bird?

      Just want to throw that out there. Look at the following sites (sorry, my web-based email won't send functional links, so you'll have to copy & paste the URLs):

      http://www.surfbirds.com/cgi-bin/gallery/search2.cgi?species=Yellow%20Grosbeak

      http://www.umd.umich.edu/dept/rouge_river/reprint.html

      http://www.birds.cornell.edu/pfw/news/DeformedBeaksAlaska2003.htm

      http://www.absc.usgs.gov/research/bpif/chickadees.html




      Thomas Miko (Mikó Tamás)

      thomas.miko@...
      thomas_miko@...

      653 S. Indian Hill Blvd., #C
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      -Oscar Wilde
    • Kimball Garrett
      Re: Bill shapes (and deformities?) in Yellow Grosbeaks.... While I agree we have much to learn, I can categorically state that hatch-year Yellow Grosbeaks have
      Message 2 of 2 , Aug 7, 2006
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        Re: Bill shapes (and deformities?) in Yellow Grosbeaks....

        While I agree we have much to learn, I can categorically state that hatch-year Yellow Grosbeaks have "normal" bill shapes (as evidenced by 25 skins in our collection, including several HY/SY birds). The apparent small maxilla (= "upper mandible") relative to the (lower) mandible (i.e., the "underbite") of the Big Pine and Albuquerque birds (i.e., the "underbite") is not indicative of immaturity in any way. I have no idea whether such a deformity should be construed as indicative of prior captivity. And, again, the black and white flight feathers of the Big Pine bird suggest that it is more than one year old (unless those feathers are fresh and new, something that does not appear to be the case). So we can dispense with the "odd bill shape = immature" argument.

        KLG

        Kimball L. Garrett
        Ornithology Collections Manager
        Natural History Museum of Los Angeles County
        900 Exposition Blvd.
        Los Angeles CA 90007
        (213) 763-3368
        (213) 746-2999 FAX
        kgarrett@...


        > -----Original Message-----
        > From: CALBIRDS@yahoogroups.com [mailto:CALBIRDS@yahoogroups.com] On Behalf
        > Of Thomas Miko
        > Sent: Friday, August 04, 2006 9:59 PM
        > To: calbirds@yahoogroups.com
        > Subject: [CALBIRDS] Y Grosbeak bill shape thoughts
        >
        > Okay, caveat's over. Here's what I have been up to: This whole allegation
        > that the Albuequerque and the Big Pine Yellow Grosbeaks are Tijuana
        > Specials i.e. escaped cage birds is killing me, especially since to me the
        > bill is not misshapen, just misproportioned. I have written to some
        > people in central Mexico (seeking their expertise on Yellow Grosbeaks) in
        > bad Spanish, and haven't heard back. I also wrote to someone in Alaska
        > who is working on bill deformities. Links to all will be below. Here's
        > the thing that struck me: The Tucson bird had "the right bill shape", but
        > it was a full adult. Our bird and the New Mexico bird were immature
        > males. So, how do we not know through our collective lack of experience
        > with central Mexican birds on their home turf that it is totally normal
        > for the immature birds to look like this, and only the adult males have
        > the bill shape that we see on the Tucson bird?
        >
        > Thomas Miko (Mikó Tamás)
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