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Mystery Snow Story: Great Horned Owl Preys on Black Guillemot

Plate-219,-Black-GuillemotLet me first say that the scenario I describe is conjecture, albeit conjecture based on the evidence posted yesterday. Today’s post may well tell you more about my train of thought when interpreting signs in the snow than the actual events that took place! The tracks were discovered and photographed by Sally Grassi of Camden, Maine, who saw a large bird (I thought that telling you this would be giving away too much!) devouring something while perched on the snow at night. The tracks that may appear to some as leading to and from the kill site are marks made by something that came out of the sky – they come from and lead to nowhere. I apologize if they were misleading. Given the myriad of ways this scene could be interpreted, the guesses made were strikingly on the mark. Kudos to Kathie Fiveash, who correctly guessed the prey species.

Plot: A bird of prey attacked another bird and proceeded to consume most of it.

Characters: As to the species of predator, the fact that this activity took place at night points to an owl, and the size of the bird eaten (deduced from the size of its remaining foot and bones) narrows the attacking bird down to most likely being a Barred Owl or a Great Horned Owl, both of which are found along the coast of Maine in the winter. (Snowy Owls are diurnal and therefore, even though there are individuals that have irrupted into New England this winter, the likelihood of it being a Snowy Owl is minimal.) Although we can’t know for sure which species of owl it was, chances are great that it was a Great Horned Owl, as they routinely eat large prey, and Barred Owls only occasionally feed on birds this size.

As to the identity of the prey — the geographic location, the time of year, the few remaining feathers and the color of the remnant (unwebbed) foot and leg appear to eliminate all but the Black Guillemot. Although totally black with white wing patches during the breeding season, this alcid (member of the family of birds that includes puffins, murres and auks) has a mostly grey/white plumage in the winter, and brilliant orange-red legs and feet year round. It can be found throughout the year along the coast of New England where it hunts for fish, crustaceans and invertebrates in shallow water near shore. (Thanks to Sally Grassi for Mystery Photos, to George Clark for confirming prey I.D. and J.J.Audubon for the Black Guillemot illustration.)

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7 responses

  1. Marilyn

    Black Guillemot has webbed feet. That isn’t obvious in the “aftermath” photo, but it does swim…

    February 17, 2015 at 8:13 am

  2. robertwyatt

    Amazing! Being a ignorant Cape Cod denizen, I imagined that a bear had killed a swan! Your articles and photos are marvelous. Robert

    February 17, 2015 at 8:25 am

  3. Kathie Fiveash

    The strange thing about this story is that I have never seen a black guillemot out of the sea except when nesting. Perhaps they haul out on ledges at night, but I have always thought that they sleep on the water. I guess not. The alternative is that the owl scooped it from the sea surface, which seems pretty unlikely, but maybe. Coastal eagles prey mostly on seabirds since the demise of abundant ground fish due to human overfishing. But when an eagle hunts a bird, it goes into the water during the capture, and swims to land or ledge by rowing with its wings.

    February 17, 2015 at 8:49 am

    • I am with you, Kathie. It’s not crystal clear who the predator was…I try to tell myself when I am not 100% sure of something that that’s part and parcel of a mystery, but it can be very frustrating!

      February 17, 2015 at 9:09 am

    • Louise

      Nice detective work, Kathie! Landlubber that I am, I couldn’t get the prey species and didn’t know Snowy Owls were diurnal. I did see a new bird at my feeder today and crows in the field below the house (first sign of spring for me!). I think the bird might have been a pine siskin, not entirely sure as it was blown up like a toy to brace against the frigid air.

      February 17, 2015 at 5:53 pm

  4. Lucy Hull

    Hi Mary,

    Your blog is wonderful and I’m enjoying it very much. Thank you!

    On Friday we came upon the mystery portrayed in this image. This is on the salt marsh in Arrowsic, on the east side of the Kennebec River. We have a crust on the snow so no tracks were visible, but there has been a great deal of fox activity in this area. My question is whether this was a duck or a grouse, and if it was a duck what would have made the hole.

    I have closeups of the hole, the scat and the remains if they would be helpful.

    Thanks for all your posts!

    Lucy

    Lucy W. Hull 207/837-7607

    March 8, 2015 at 8:15 pm

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