[at-l] B-Owl Movement. Re: Feeling Like Spring

Cody Girl codycodygirl at gmail.com
Mon Mar 7 20:21:42 CST 2011

This is so cool!  And just yesterday I was reading a book that said that owl
pellets are "burped up" rather than coming from the other end.  This was
news to me!  Here's the paragraph:

Stong digestive jices break down the soft parts of the food but not the fur
or feathers or large bones.  These wad into a pellet of indigestible
material that the owl burps up and drops beneath its perch.

Then it goes on to talk about how awesome this is for science to be able to
dissect a pellet to figure out what the owl's been eating.  Nice work RD!

btw, the book is called "Mountain Year  A Southern Appalachian Nature
Notebook", by Barbara Hallowell.  It attempts to answer those questions you
just kind of wonder about while hiking along, in a couple of pages each.  I
like the simplicity of it.   Pretty good so far.

I want to dissect an owl pellet.


On Mon, Mar 7, 2011 at 9:48 AM, RockDancer <rockdancer97 at comcast.net> wrote:

>  Hi all,
> I’ve had a great time in past 2 weeks reconstructing the contents of owl
> pellets that I collected in the local state forest.  There is probably more
> I could learn but without any training I could sort the mess-o-bones out
> this way.
> *Site 1 – Northern Saw-whet Owl eating White-footed Mice*
> Early on I thought this site had either a Northern Saw-whet Owl or an
> Eastern Screech Owl. This is based on pellet size and the dense white pines
> where they were found. The 5 pellets contained 5 animals but only 4 skulls.
> From the dental records and skull size they are all genus Peromyscus mice.
> In my area we have only the White-footed mouse and the American Deer mouse.
> From the size of the pellet the bird is narrowed down to only the Northern
> Saw-whet Owl. Now I’d like to see it.
> Saw whet owls will kill as many as 6 mice in succession and them in Winter
> pantries. Later they will brood on the mouse-icle to thaw for eating. If
> food is plentiful they will eat only the heads. Deer mice is the primary
> prey and the pellet length is .75 inches.
> Screech owls produce 2-4 pellets each day and pellet length is 1.5 inches
> long. In the winter they will hunt open ice holes left by fishers. We have
> fishers and river otters in the woods at this location.
> *Site 2 - Great-horned Owl eating Meadow Voles and a Grey Squirrel*
> I saw the bird and the pellets are from the base of the nest tree, the nest
> about 90 feet up in a conifer. The 2 pellets I collected were a surprise
> because they contained partial skeletons, and the skeletons were perfectly
> complementary. This means the bird emptied it’s stomach in 2 “surges” and
> all the bones were in the stomach at the same time. Taken together I had 5
> skulls, 10 pair of lower jaws, 10 pair of leg bones meeting in ball-socket
> joints (like our hip-femur). All 5 animals are Meadow Voles. We have 3 voles
> in this area but the skull size determines them to be Meadow Voles.
> But the pellets also contained a mystery. An intact chest bone, a larger
> ball-socket joint (5x larger than a vole), 5 odd shaped vertebrae too large
> for vole and many flat flexible fragments of what I assume is the skull cap.
> So this owl also ate something much larger than a vole (which in this case
> is larger than the mice). Candidates are Flying Squirrel, Red Squirrel, Grey
> Squirrel, rabbits, skunk, opossum, etc. Based on population I’ll be content
> to call it a Grey Squirrel. It’s body is 2.5x the length of a Meadow Vole,
> not quite the 5x increase in size indicated. But then I don’t know how these
> things scale up. Perhaps the hip joint scales at 2x the rate for the length
> of body?
> That’s all I’ve got for this project. After cleaning and sorting the bones
> I used the kitchen microwave to sterilize all I had, tossed the rest. This
> allowed me to handle the bones without worries. Turns out you can get some
> enteric bacteria from doing this so be careful out there!
> RockDancer
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