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Contents of One Barred Owl’s Stomach

11-7-14 vole, shrews and mouse 027Fantastic guesses, given you had no measurements to work with. Very creative, indeed. Yesterday’s mystery photo was a packed version of the bodies displayed today.

Owls swallow small prey, such as mice and voles, whole, while larger prey is torn into smaller pieces before being swallowed. Once eaten, prey goes directly into the owl’s stomach, as owls have no crop, and thus no ability to store food for later consumption.

Like other birds, owls have a stomach with two chambers — one is the glandular stomach, or proventriculus, (yesterday’s mystery photo) which produces enzymes, acids and mucus and begins the process of digestion. (Because the acids are weak, only the soft tissues are digested.) The second stomach is the muscular stomach, or gizzard, also called the ventriculus. The gizzard lacks digestive glands – it serves as a filter, holding back bones, fur, teeth and feathers that are difficult to digest. The soft parts of the food are ground by the gizzard’s muscular contractions, and allowed to pass through to the rest of the digestive system.

Several hours after an owl has eaten, the indigestible parts remaining in the gizzard are compressed into a pellet the same shape as the gizzard. The pellet travels back to the proventriculs and remains there for up to ten hours before being regurgitated. Because the stored pellet partially blocks the owl’s digestive system, new prey cannot be swallowed until the pellet is ejected. If more than one prey is eaten within several hours, the remains are consolidated into one pellet. (In this case, one very large pellet!)

Update: I left the contents of the deceased Barred Owl’s proventriculus outside last night, and a resident Barred Owl recycled the Meadow Vole and Masked Shrew.

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17 responses

  1. Henry Holland

    Thanks Mary. This takes me back to our boys 1st grade science class. Hope all is well with you and your family.
    Henry

    November 7, 2014 at 1:09 pm

  2. teachdad46

    I will not be asking for this resident owl’s recommendations for local eateries..

    November 7, 2014 at 1:41 pm

    • I hadn’t realized you followed my blog, Henry! Hope you’re not regretting sharing the Holland genes after reading some of my posts!

      November 7, 2014 at 1:56 pm

    • Seems to me it was pretty selective…

      November 7, 2014 at 1:57 pm

  3. That is amazing!

    November 7, 2014 at 1:57 pm

    • I thought so, too, Kelly – many more critters than I expected to find!

      November 7, 2014 at 2:02 pm

  4. sassy55

    the best yet!

    November 7, 2014 at 2:03 pm

  5. sharonchurch

    I thought the image was of a birth, as well, and enjoyed your speculation. But this makes sense! There is an artist out here named Anne Sawyer who makes wonderful jewelry out of owl pellets. i think I may have mentioned her brooches to you. They are fabulous! Todd Noe admires them, as well. A small club of fierce afficionatos! This article reminds me that I should buy one!!!!

    xxoo

    S.

    November 7, 2014 at 3:00 pm

    • Does Anne have a website? Her jewelry sounds like it’s right up my alley!

      November 7, 2014 at 3:41 pm

  6. Mary, despite how gross the initial photo challenge was, this was incredibly fascinating, educational and SO entertaining! I had no idea owls could store so much in their stomachs. And reading all the guesses (and your comments) made me laugh so hard. I’m still laughing, that was great…. Thank you!

    November 7, 2014 at 4:09 pm

    • Thank YOU, Susan! I had a lot of fun with this, and hope others did as well.

      November 7, 2014 at 5:59 pm

  7. Caroline K.

    Update: I left the contents of the deceased Barred Owl’s proventriculus outside last night, and a resident Barred Owl recycled the Meadow Vole and Masked Shrew.

    Hilarious. What a fascinating post. Thank you, Caroline Keating

    November 7, 2014 at 5:04 pm

  8. Sad the world lost such a good pest controller. It’s a pity. Great post, Mary.

    November 8, 2014 at 1:20 am

  9. judilindsey@comcast.net

    Mary,  Fantastic information! Thanks so much for your posts! Judi

    November 8, 2014 at 2:39 pm

  10. I liked the puzzle of the stomach very much. I was close but did not remember that owls can take smaller prey down whole. One of the things we did when I was with Tom Brown years ago is to get down in the grass and just examine for a good long while what is going on within one square meter- plenty! A very good exercise.. Ricker

    http://www.rickerwinsor.com

    http://rickerw.wordpress.com

    November 10, 2014 at 1:15 am

  11. Marilyn

    So that whitish “fur” is feathers!

    November 10, 2014 at 12:07 pm

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