Living the Scientific Life (Scientist, Interrupted)

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[Mystery bird] Rose-breasted Grosbeak, Pheucticus ludovicianus, photographed in a Houston backyard in Texas. [I will identify this bird for you in 48 hours]

Image: Joseph Kennedy, 21 April 2010 [larger view].

Nikon D200, Kowa 883 telescope with TSN-PZ camera eyepiece 1/250s f/8.0 at 1000.0mm iso400.

  1. Based on this bird’s beak shape, what sort of diet would you expect it to have?
  2. This bird primarily eats seeds, as indicated by the heavy beak and the angulated commissure (that sharp angle at the point where the cutting edge of the bill (tomium) meets the corner of the mouth (rictus).

  3. What are those long, stiff hair-like feathers growing at the gape next to its beak known as?
  4. Rictal bristles.

  5. What additional information about this bird’s diet does the presence of those modified feathers suggest?
  6. Unknown. The precise function of rictal bristles is not known with certainty, but this might be because these modified feathers perform different functions in different species. But currently, it is thought that rictal bristles provide tactile information to birds — similar to the whiskers in cats.

Review all mystery birds to date.

Comments

  1. #1 Russell
    April 30, 2010

    Excellent! Moving from species identification to comparative anatomy. I love it. As to species, I think the same as was shown not long back.

  2. #2 Dan
    April 30, 2010

    That’s the species that got me addicted to birding so many years ago!!!!!

    When it visited my birdfeeder, I thought it was the most amazing thing. It inspired me to sign up for a field ornithology course, and following migration so passionately.

  3. #3 bardiac
    April 30, 2010

    What GREAT questions! First, this is an absolutely stunning photo! Thanks for sharing it.

    The beak shape makes me think of a tough, seedy diet. It’s robust, especially top to bottom, which seems that it would give strength in that I-Beam sort of way. That’s valuable when a bird is trying to eat something tough or to break through seed coats.

    When I had a conure way back when, it would use a similar notchy area of the beak to sort of hold seeds in place and keep them from slipping while it cracked the outer coat. And then it could manipulate the seed coat to drop and eat the inside. I’m guessing the notchy place here works in the same sort of way, though it’s differently positioned. If so would that be an an example of homologous evolution in different groups of birds?

    The specially modified feathers are, I think, rictal bristles. I think of these as a flycatcher thing, so that might indicate that this bird also catches insects (on the fly?) and eats them.

    During the summer, I’ve had pairs of these (if my ID is correct) nesting near my home, and the female especially tends to visit my suet feeder fairly regularly. That surprised me at first, but if they also have an insecty diet, then visiting a suet feeder would make a lot of sense, I suppose.

  4. #4 bardiac
    April 30, 2010

    I just read up a bit on rictal bristles (thanks, Google) and the articles seem to think they’re not so much to help catch insects as to protect the eyes from stuff (like insect legs poking about). Fascinating!

  5. #5 "GrrlScientist"
    April 30, 2010

    russell: good call. not only did i show you a photo of this species last week, but it was the same individual, if i am not mistaken. since i am focusing on anatomy and the hints it provides about avian natural history, i decided it would be okay to show the same bird again. (hopefully, you’ll forgive me for the redundancy)

  6. #6 arby
    April 30, 2010

    When you posted this one last week, I whined that I hadn’t seen one yet this year, in central KY. I’m happy to say the first one showed up this morning. I also complained that I don’t get to hear them sing much, as soon as they start singing they leave me and head north. I said I have to get my ear candy from the wood thrush, and the first of the season showed up last evening. What a wonderful voice.
    Heavy rain predicted tomorrow, Grrl, bet on the mudder. rb

  7. #7 Jessica
    April 30, 2010

    Fun series. Not sure the drill, should I state here what I think it is, or not give it away?
    My identification is based on the breast plumage, and the type of bird it is from the beak.
    Beautiful bird too, used to see it in my garden in Canada.

    Another question, do you do requests? There’s a duck species that was wintering in the NYC east river that I can’t identify! I could send a pic :)

  8. #8 apikoros
    April 30, 2010

    May I add a question that I have wonde3red about for a while:

    What are bird beaks made from?
    Are they chitin? (evolved from hair); bone? (ancestral jawbone stripped of flesh); dentin and enamel? (ancestral teeth, fused)?

    I know that they grow from the base and wear over time, so I’m guessing either #1 or 3, but I’d like to know.

  9. #9 "GrrlScientist"
    April 30, 2010

    jessica: i do show readers’ mystery birds if they can get a decent photograph, and sometimes even when they can’t. send the image to my gmail address and i’ll see what i can do.

    apikoros: bird beaks are made from bone with a layer of keratin that grows over the bone. when a bird has a colorful beak — think puffins, for example — it is this keratin layer where the pigments are located. i wish i had you in an ornithology lab so i could show you instead of describing it to you (or at least, so i could draw a picture since that is so much more interesting and satisfying than just a written description).

  10. #10 Apikoros
    April 30, 2010

    Thank you! That answers not only what I asked, but the further question of where the color is. I didn’t think chitin was strong enough to crunch through some of the things that I know birds eat, but I don’t know of any animal that grows exposed bone*. Bone sheathed in chitin explains it perfectly.

    I know they grow out from the base by observing the starlings in front of my office over the course of the year. Their beaks grow out black in the fall and yellow in the spring. I had one (alas, gone now after three years) whose beak failed to wear normally… after three years it was over 2cm and banded dark and light by year. (Want a picture? I have one. Teratologies fascinate me :-)

    *just because I’ve never seen it does not mean it does not exist and I know very well never to say never about animals! They’ve evolved the most amazing structures!

  11. #11 psweet
    April 30, 2010

    Apikoros — Deer antlers are actually exposed bone, although they are covered with skin while growing, and I believe that the living portion of the bone dies before the bone is actually exposed.

  12. #12 apikoros
    May 1, 2010

    I’ve put photos of the unusual starling at:

    http://picasaweb.google.com/stevendolan/NewAlbum51101055AM#

    if anyone is interested.

  13. #13 arby
    May 1, 2010

    Wow, apikoros. That really is strange looking.

  14. #14 apikoros
    May 1, 2010

    I know, arby, I fed this bird for two years at leastand it lasted through to this winter, disappeared in Dec/Jan so it had a good run. It had to turn its head sideways to pick up peanut pieces, but I’ll bet the extra-long bill might even have been an advantage in probing for insects.

  15. #15 apikoros
    May 1, 2010

    psweet, thank you! I knew, even without having seen it, that there would be an example out there.