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Mystery Photo: Bald Eagle or Osprey Pellet


Congratulations to Jill Osgood (“osgoodjill”), the first reader to correctly identify the pellet of either a Bald Eagle or an Osprey.  Many people are familiar with bird pellets – lumps of material consisting of the indigestible parts of a bird’s diet which are regurgitated by the bird hours after they’ve eaten their prey.  Raptors often consume their prey whole, including parts that are not easily digestible such as fur, feathers, bones, teeth, nails, etc.  These parts get as far as the proventriculus, an organ located between the esophagus and the gizzard, where they are packed into a pellet.

We often associate pellets with owls, but many species of birds, in addition to owls and other birds of prey, form pellets.  They include grebes, herons, cormorants, gulls, terns, kingfishers, crows, jays, dippers, shrikes, swallows, and most shorebirds.  The size of the Mystery Photo pellet (3” long) indicates that the bird that regurgitated it was very large – in general, the larger the bird, the larger the pellet.  It was found near the shore of Lake Champlain, where Ospreys and Bald Eagles are not uncommon.

If I had to, I would guess the pellet was regurgitated by a Bald Eagle. Osprey are piscivores, eating primarily fish, and bald eagles are carnivores, eating a variety of fish, mammals and amphibians. A close look at the pellet reveals, in addition to fur and fish scales, the upper mandible of a very small rodent on the left hand end of the pellet.  An Osprey’s pellets consist of primarily scales and bones, whereas a Bald Eagle’s pellets are composed primarily of hair (its stomach acid breaks down the bones and scales).

Twelve to eighteen hours after consuming prey, a Bald Eagle casts a pellet. Relatively odorless and light-weight, these pelleted remains can reveal the varied diet of this raptor.

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6 responses

  1. Tom Stearns

    Hi Mary,

    The attached photo might be a good one for your next mystery post. Once we determine what it’s from! Let me know what you think or if you have any questions. It was pointed out to me by my friend Kathryn Donovan in Montpelier who saw it appear overnight in her wood pile. Ash.




    Tom Stearns
    Founder and Chairman

    Mobile: 802-224-6301

    High Mowing Organic Seeds
    76 Quarry Rd.
    Wolcott, VT 05680 USA

    August 3, 2020 at 8:37 am

  2. Andy Hutchinson

    Andy Hutchinson

    August 3, 2020 at 10:42 am

  3. Andy Hutchinson

    Mary, could it have been from a large heron or egret?

    August 3, 2020 at 10:44 am

    • Great question, Andy. Great Blue Herons do regurgitate pellets! I’ve only seen one regurgitated once, from a distance, and it didn’t appear to be this large, but it may have been! My guess is a great egret’s pellet is smaller as well, but I honestly don’t know if it is.

      August 3, 2020 at 2:34 pm

  4. So interesting!

    August 3, 2020 at 1:10 pm

  5. Alice

    That is so very interesting. The shores of Lake Champlain will give you lots of exploring area!

    August 7, 2020 at 1:35 pm

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