Tuesday, December 20, 2022

Winter for the Birds

Hermit Thrush

Looking out on our backyard I could watch robins, cardinals, bluejays, wrens, doves, house finches and sparrows taking turns at the heated birdbath. Barb has created an island of 100 native plant species in a neighborhood sea of sterile mowed yards. While the plants are barren except dried seed heads which the finches feast on, they still provide a degree of shelter while waiting their turn at the feeder

As we tell the WOLF students, "Everything has to survive winter.....or else..." Whether by hibernation, migration or adaptation, every living thing has to survive winter or go extinct.  Our migrants have already left for their southern vacation and the only bird that hibernates is the Common Poorwill which doesn't live in Missouri. That leaves the hearty adapters that we see around our feeders.

Although several sources say the Poorwill hibernates, it actually goes into torpor.  Three things differentiate hibernation from torpor. Hibernation is voluntary, is driven by shorter daylight hours, and waking up can take hours and use a lot of energy. Torpor is involuntary, and results from falling temperatures (regardless of daylight hours), and the animal wakes rapidly by shivering, which expends energy, but conserves a lot more than hibernators use.

There are things that we advanced bipeds can do to increase their odds, improving their quality of life and benefiting from watching them in winter. You can keep water sources open, provide higher energy feeds (suet, black oil sunflower, shelled peanuts, etc.), and maybe leave a little extra on the ground for squirrels if using squirrel “proof” feeders.

Photo - Steve Martin

Teeth marks- click to enlarge









Down on Bull Creek it is time to hang up the feeders again. A bear on our deck reminded us this year that we hung up our feeders a little too early. It tore down a feeder hanging on a wire five feet above the deck, leaving its tooth prints as dents in the hard plastic. Now that Bruno is hibernating, or at least doing the intermittent Missouri version, it is time to hang them out again.

On our deck above the creek a lot of other critters don't understand the "bird" part of bird feeder. We have a special squirrel feeder with a spring bar that closes the feeder when any weight is on it. The squirrels have learned to put a paw in first to keep it open while they gorge. For a while we had a battery operated feeder that was supposed to give a little shock to a squirrel. I took it down before these smart little rodents could run a wire out to an nearby drey for lighting.



My favorite visitor was this opossum.  I was able to walk out on the deck and get within two feet of it for closeup photos before it turned around and got back to business licking the suet feeder.

Bill Bryson says: "Life just wants to be."  Lets help it all the way up and down the food chain.

Thursday, December 1, 2022

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.