Owl Pellets

I received a gift of owl pellets from Ben Caruthers.  While this might not excite you, it got a rousing welcome from our friends in the 5th grade WOLF School.  I asked Ben for the backstory.

"The barn is on a cattle ranch where my father-in-law works as a cowboy. I asked the owner if I could place an owl nest box in the old barn. I had not seen any sign of an owl. This was just in the hopes that an owl would find the box and nest there. At the same time I placed a trail camera to monitor any bird activity. It took two years, but the barn owls finally showed up."

There has not been any sign that they have actually nested in the box, but they used it as a perch.  Several other birds have shown interest in the box including rock pigeons, European starlings, American kestrel, and squirrels. Turkey vultures have used the barn for nesting. Once when I went to check on the nest boxes there were two large, white turkey vulture nestlings. They spread their wings and hissed when I approached. I got out of there quickly so I didn’t disturb them further. I also didn’t want to experience their alert response. 

The most recent check I made of the owl box I got to see the barn owl above in person. It flew right over the top of my head!"

=========================================

Ben collected over one hundred owl pellets on the floor of the barn below the nest box and from two other cross beam perch areas.  He delivered them to me separated in paper egg cartons.  Note to self - don't eat any eggs shared by Ben.  The contents were dry for months and some had been cleaned by some clothing moth larvae described in this previous blog.

Barn owls are carnivores, specializing in mice, moles, voles and birds.  Since they swallow their prey whole, passage of bones through the intestine is impossible.  Even the thought of that hurts!  The food bolus goes first into a glandular stomach for digesting with enzymes, acids and mucus.  Next, on to the muscular stomach (gizzard) where it is mechanically mashed up and the digestible portion move down the tract.   Fur, bones, teeth and feathers are retained until they are hungry later when they will be compressed into a "pellet" pushed out.*

By now, I am sure you are anxious to see what is in a pellet. The photo above is a single pellet which also had some leg bones, ribs, etc.  With the charts below* you can begin to determine which rodents passed on (or in this case passed up) after encountering an owl.   Biologist can even survey rodent populations by studying the pellets in the area.

______________________________________________________________

* Hungry for more details?  Check out this World of Owl site.  More on studying owl pellets is at this site.  A key to identification is here.