Building Backyard Habitat for Barn Owls: Lessons from a Lifelong Naturalist

Reader Contribution by Tom Stephan
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There it was. A barn owl nest box hanging in a low branch of a spreading sycamore tree. I was bidding to trim the tree at the time and I mentioned to my prospective client that it was too low — owls would not nest there because they had no privacy. She wanted to know how I knew, and I explained that I had been a falconer all my life, and that I had climbed and studied all species of raptor nests.

She told me her late husband had hung it, but that was as high as he could on a ladder. If she got owls, maybe she could watch the babies while doing the dishes. I offered that if she awarded me the tree job, I would move the nest box higher up gratis and she immediately accepted.

Three days later on a sunny Saturday morning, I got a phone call. My client was excited, and bubbling over that she was hosting her bridge club and someone noticed a pair of owls up in the newly placed nesting box, staring down at the house.

I was hooked.

All nine of her friends wanted an owl box as well, and it dawned on me it could be a business. That was over 30,000 barn owl nesting boxes and 27 years ago.

A Lifelong Naturalist’s Knowledge of Barn Owls

During those 27 years, I’ve studied and researched barn owls and my fascination with them has never ended.

Barn owls have the best hearing of any bird — I believe they can hear your heart beating if you’re close enough to the owl house. They have a primitive echolocation capability and can navigate by a clicking sound. There is a record of a totally blind barn owl in Texas that was “making a living” alongside a roadway. By hopping from fence post to fence post, it could detect and catch rodents in the grass.

Their entire face is a sound-gathering sonic dish, which channels and amplifies sound to a pair of offset ear drums, allowing them to triangulate on sound. This aids in hunting and navigation. Perched or flying, they can hear a rodent excavating dirt to the ground’s surface, after which they loiter over the hole. When the rodent emerges: dinner time.

Barn owls have an elevated metabolism, thus their need for calories is extremely high. This makes the barn owl very desirable for home owners and large property owners wishing to rid their property of rodents. One study showed that barn owls consume as many as 2,000 rodents per year, per pair, when feeding their young. These are mostly rats and mice, but moles, voles, gophers and snakes will do. In San Diego, I saw a barn owl fly out of the dark, grab a grunion fish and fly off with it. Variety is the spice of life, I guess.

Creating Backyard Habitat for Barn Owls

Attracting barn owls to one’s backyard is most effective after you understand what the owls want and need. They can be attracted to take up residency in a bewildering array of artificial man-made cavities. Yes, boxes designed for them are best, but I’ve seen them in everything from an old dairy type milk can to an almost-full bucket of sand in a metal garden shed.

It’s important for an owl box installer be aware of which direction the birds prefer and which directions they reject. Most of the boxes installed here in San Diego, are hung by chains in trees. Insects are attracted to these boxes as well, and keeping them out is a significant “trick of the trade.” It took a number of years and many attempts to come up with a nontoxic to owls formula which I paint on the ceiling that prevents bees from colonizing the boxes.

These birds begin to nest in the lower United States latitudes by about February. As with all life, barn owls need three things on their shopping list: Water, food. and cover. They get all the hydration they need from the food they eat, so those first two bases are covered. Add one or two nest boxes (two is better but not a rule), his and hers, and it’s just a matter of time before they move in.

What a delight it is when they come to stay. Their courtship is an amazing feat and quite aerial with the male circling up higher and higher, then diving straight down, only to pull out of the dive, miss the female by an inch, and shoot directly into the nest box — all the while sounding his best “come hither” calls.

Barn Owl Nest Boxes for Backyard Wildlife Habitat

Why are nesting boxes needed? Because urban and suburban areas lack many hollow trees, which are their most common nesting sites. What do we do with a hazardous hollow tree in residential areas? We cut them down, and as they topple so do the potential barn owl homes.

The configuration of the nest box is important. I originally copied that first owl box’s design. But soon I came to realized that it had room for improvement. I have been a falconer for 45 years and captive bred birds of prey for about 12 years. I applied what I knew about the needs of nesting raptors to the owl box improvements.

The doorway was up high on the face of the box. Most owl box companies have them configured this way. In short order, the box will fill with the cast off pellets, grass and detritus all the way up to the bottom of the doorway. Now the owls quit nesting as there is no room to stand up inside the box.

Someone now needs to get back up to the box or bring it down to be cleaned. This is problematic in a number of ways. The box must have a clean out hatch on the backside with hinges and a hasp, adding to cost.

The plywood must now be thicker than the 1/2-inch CDX to 5/8-inch, adding to cost. The cutting of the hatch and installed the hinges and hasp adds to the labor cost in time.

Often the owner is not aware that the birds start nesting as early as December (in San Diego) and if they “double clutch” as raptor propagators say, or, the laying of a second set of eggs, they may end the season as late as mid October.

The person climbs up or takes the box down at the wrong time and scares away the owls and possibly breaking the eggs, a barn owl catastrophe. I have to say here that I have never heard of a human catching a disease from a raptor but the litter from the box is quite disgusting with a pallet closing quality all its own. It doesn’t reek downwind but smells funky enough that I do not want my clients exposed to it.

 “What if there is a way to allow the materiel to fall out on its own? ” I queried the guy in my head I call myself. So I cut down the little round doorway and knocked out the tab. The door now resembled a tombstone. I installed it in a tree along my driveway to test it. Five weeks later I pulled up under the tree and gathering up my phone and briefcase, I heard the neighbors. It sounded as if someone was hand sanding some wood close by. There was dust floating about but I was alone.

Following the dust trail up, I saw it emanated from the owl box. The female was vigorously scratching the debris using her toes like two leaf rakes, flinging the dust and pellets from out the now enlarged doorway. She was cleaning the box!

That pair of owls successfully reared five owlets to fledgling that season. Now all of my boxes have this design and no other as there is no longer a need to clean the boxes. Plus, the cleaning is part of the nest building and pair bonding process. Exactly what a newlywed human husband or wife does to a first home: He or she gives it a thorough scrubbing, top to bottom.

FYI, the owl pellets have value to help one offset the cost of the box. Just call your local Jr. High school biology teacher and inform them that you have owl pellets. They will buy all you have. Going rate? Between $3.50 to $5 per pellet! The students dissect them and study the quantitative total.

There are many methods to sterilize the pellets before dissection. Here is the most efficient method I have found. Pour one cap of bleach in a red solo cup and fill 3/4 full of tap water. Add the pellet and leave it in there over night. The next day, pour out the water, then drop the pellets on some newspaper. It will now come apart easily and is quite sterile.

The last advantage to an 8-inch door way cut to the deck is that occasionally there will be an early heat wave.  April and May heat is tough on young owls as they cannot fly away yet to a shady tree yet and must suffer the temperature inside the box. This is where a tree mounted box is better than the pole mount option. The pole mount is better that the tree mount because the box can be installed and directed wherever the best spot is for both parties.

My most popular barn owl box includes a wireless night vision RF camera. I stumbled onto the idea long before internet technology was around when I put a baby monitor camera in my father-in-law’s barn owl box and wired it to his TV. My father-in-law Tony is a wonderful man, but holds no special affinity for birds other than fried chicken.

Soon a pair of barn owls moved in.

Video Systems for Backyard Birding and Owl Viewing

In short fashion Ol’ Tony was calling all his relatives back in the motherland of Ohio, gushing about how much fun it was to have the birds courting on his television screen. I saw enthusiasm in a man who is not particularly enthusiastic. Back then, it required a trip to a “spy supply shop” and $3,200 worth of surveillance equipment and to make a camera enabled box, but now this gear is readily available and affordable. If you’ll allow me to boast a bit, Cornell University of Ornithology attributes the original concept of “consumer” owl monitoring to yours truly. (A feather in my cap?)

Today, thousands of my nesting boxes with night-vision video cameras have been purchased and installed in back yards, natural history museums, and connected to TVs in science class rooms.

Here’s an odd fact:  Because of the way owls consume their prey, their “pellet” droppings are a discarded in the shape of balls of fur, with bones and other undigested material more of less undisturbed. You’ll find on Amazon dozens of “pelletiers” who sell owl pellets to science classes for three dollars apiece! They are used primarily for dissection, which teaches students about the food chain and nature’s symbiotic ecosystems.

About 10 years ago, one of my clients’ grandsons was pondering a science project for a college class, and when he saw the owls on the TV he commented, “We could patch that video feed into the Internet!” In short order, he did so.

Their streaming owl-cam experienced 21 million “hits” in 9 months, and 42 million in two seasons. They named the pair of owls after a comedy radio troupe, “Molly and McGee,” with Molly as the star. Don’t believe me? Google “Molly the Owl.”

Barn Owl, Tyto Alba and its variants are found globally on every continent but Antarctica, especially farms, ranches and cities. I hear there is a pair nesting in Yankee stadium. I could easily install a string of owls boxes starting with one near this nest and bridge the owl population to any surrounding neighbor hood.

If I had my way, I would be allowed to extend this to the state and to the entire the North American continent. And why not? No other method kills more rodents with so little effort. One builds or buys and installs an owl box. One and done.

Tom Stephan works in the green industry treating sick trees to improve their vigor and vitality through anti compaction and soil fertility. He is a former certified arborist, a master falconer, and has incurable minimalist tendencies. Connect with him atBarnOwlBoxes, and read all of Tom’s MOTHER EARTH NEWS blogs.

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