Naturespeak A naturalist's view of the world

December 20, 2010

The Eating of the Shrew

Filed under: Uncategorized — wykes @ 11:23 am

Saw-whet Owls have not been spotted around Lake Erie Metropark since late fall, but it is very likely that the tiny predators are still hanging about for the winter. They are northern birds, after all, and not at all adverse to our relatively mild winters. Unfortunately, since they are so small and secretive, the actual act of seeing one becomes a matter of luck. The name “Saw”-whet is somewhat of a misnomer. Getting a chance to interview one? Well, that opportunity is even rarer unless you have a mist net handy. One of the last visible Saw-whets, although it departed before I reached the scene, did leave behind a press packet before leaving. His information packet did not include any 8” by 10” glossies or resumes, but it did answer at least one of my potential interview questions: “When visiting here, what is your favorite food?”

His “press packet” was in the form of a matted lozenge of hair and bone, or, if you prefer more exact verbiage, a pellet. I picked up the packet and picked it apart to reveal the answers contained within. Now remember, a pellet is not a poo so please don’t get all weird about touching something like this. These two items come out of the opposite ends of the bird. Just remember this phrase: poo is butt propelled and pellets are beak propelled. A pellet is a bundle of indigestible fur and bones which are egested, or coughed up while a poo is the end result of digestion which….now really, are you going to make me go on? My secretive Saw-whet did leave some of the other stuff dripped upon his perch, but it was the beak propelled matter that mattered to me. No, I did not touch the poo.

To those of you who are familiar with pellets and the products they contain, I realize the previous paragraph was probably un-necessary. Remember, however, that we often have to explain to the uninitiated why road kills, dung, pellets, and other cast off remains are useful.

Saw-whet pellet before opening

As stated previously, the pellet was lozenge-shaped and a hair over 1.75 inches long (that was a pellet joke intended for the initiated). This shape, as a matter of fact, could be described as “shrew-shaped” – an ironic trait as it eventually turned out. Armed with a pair of tweezers and a pair of fingers, I carefully pulled the tightly packed unit apart.  Within seconds, a shrew skull came into view and I was delighted to find that it was complete. The rest of the bones represented the usual variety of leg, hip, and vertebrae. Once all the skeletal parts were extricated and laid artfully into a circle of death it became apparent that at least two creatures were represented (see beginning photo).

For any pellet-picker skulls are a must because they are virtually the only easily identifiable micro-skeletal parts. It is near impossible to tell anything from the smaller bones (not impossible, but veeeeeeery hard). The identity of the skull in this case was obvious. It came from a Short-tailed Shrew (see detail below). Shrews, although mouse-like in size, are hyperactive little predators equipped with sharp reddish brown teeth and “fangs.” Short-tails can inject a paralyzing venom into their victims (mice, worms, insects) via large modified incisors and these teeth are very apparent features – both on the skulls and in life (see dental exam photo here). Most mammalian predators won’t eat shrews because they are musky but Saw-whets apparently like the pungent bitter taste of shrew (I would equate this with people who drink martinis).

About half of the remaining bones in this packet were from this shrew. Most pellet bones are white, but for some reason those from the shrew were still red with blood. A perfect set of pelvic bones, some long bones, and a wide assortment of ribs and vertebra were of shrew origin.

There was an additional set of long bones and a pelvic assembly in the pellet that could not have belonged to the shrew unless he was a double-hipped freak of some sort. These bones, which were white, came from a slightly larger mammal. Since there was no skull to complement this assemblage I would have to guess White-footed Mouse as the previous owner of these bones. They could be from a House mouse as well, but that is too hard to tell. The mouse’s head, the one thing that would answer this riddle, is in another pellet out there somewhere.

None of these results are radically different from the expected. Food studies on Saw-whets typically rank mice, such as White-footed and House, along with Short-tailed Shrews as normal fare. The mice are definitely preferred, but the shrews do make a 3%-10% showing. If nothing else, our little pellet discussion has at least confirmed that one of the primary Saw-whet Owl jobs is to create dead-headed mice and to turn Short-tailed Shrews into Short-lived shrews.

4 Comments »

  1. I finally came across a reasonable explanation of “Saw-whet” – it is a corruption of a French (French Canadian?) word for small bird. I was talking with a French Canadian a year or two ago when she said, in French, something about a small bird, and by golly, the word was a dead-ringer for “saw-whet”!

    Anyone who says it is because the owl makes a sound like a saw being sharpened on a whetting stone ought to have his hearing examined.

    Comment by Ellen — December 20, 2010 @ 8:54 pm

  2. Hi Ellen:
    I believe the word you heard was probably “Choette” – (pronounced something like Sh-wet”? This is apparently an alternate French word for owl – maybe it’s a French Canadian thing that could be applied to this little owl (as in “petite choette”)? The usual continental Frenchie word for owl is “hibou”.

    You’ve provided some food for thought here. I agree that the Saw-whet / saw-whetting sound is a stretch for our modern ears but then again sailors once thought sea cows were mermaids!. At any rate, I’ll have to take one of those huge lumberjack saws into the woods one frigid night and go at it with a whet stone to see if I can call in a choette with it. Now look what you’ve talked me into!

    Au revoir.

    Comment by Gerry Wykes — December 20, 2010 @ 9:31 pm

  3. The word is “chouette”. It is indeed french. it refers to an owl without a crest. A ‘chouette effraie’ is either a barn owl or screech owl. A chouette chevêche is a little owl. A chouette hulotte is a tawny owl. I have no idea why they have two words for owl, both hibou and chouette. Maybe one is older than the other, or one borrowed from another language. An hibou has ‘ears’ or tufts on the head, while a chouette does not. That is probably why they have the two different words, to distinguish between these two types of owls.

    Comment by Cathy Creswell — March 17, 2011 @ 9:39 pm

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