Most birds wait for warmer weather to pair off, but large owls like the great horned owl and the barred owl begin breeding in winter.
So, after my father recently made me a barred owl house, I knew I’d better put it up as soon as possible. If I’m lucky enough to attract a mating pair, they’ll likely continue to use my nestbox over multiple years. Barred owls mate for life. And each breeding season the female can lay up to five eggs.
Like many animals, owls have been negatively affected by loss of natural habitat. By providing suitable shelter, you can help these unusual creatures while also reaping some benefits yourself.
For instance, small screech owls help keep populations of insect pests in check. And larger owls eat rats, mice, voles and other small mammals—critters that might otherwise help themselves to whatever’s growing in your garden.
Owl Nestbox Know-How
Your region and the kind of habitat you have to offer will determine the types of owls you may be able to attract.
The great horned owl is distributed throughout North America. The barred owl is common to the eastern U.S. And, for its part, Canada has the great gray owl and the snowy owl, among others. There are eastern and western screech owls, long- and short-eared owls, barn owls and many others. Some of these prefer to live near more heavily forested areas. Others are perfectly content perched in suburban trees.
The nestbox size and entrance diameter will vary, depending on the owl species you’re targeting. (However, for great horned owls, you’ll build a nest cone, rather than a box.) Check out The Cornell Lab of Ornithology’s “Right Bird, Right House” online tool to find nestbox plans suitable for your location and habitat type.
I applied a couple of coats of waterproofing to the outside of my nestbox to help it to last as long as possible.
I also attached some spare roofing shingles to the top, letting them hang over about half an inch all the way around. Finally, I added a few inches of pine needles inside the bottom of the box. Provided they are chemical-free, wood chips or dried grass can work well for this purpose, too.
To attract a pair of barred owls, I would need to install my owl nestbox between 15 and 30 feet up in a sturdy tree. But, terrified of heights, I didn’t want to clamber up my extension ladder to do the job myself.
Fortunately, I didn’t have to. A certified arborist with Bluestone Tree, Matt Baldwin has experience installing owl houses, and, during a stint as a wildlife rehabilitation volunteer, he even scaled trees to put young birds of prey back into their respective nests.
“You want the nestbox to be about 150 feet away from residences and a quarter mile from other established nests,” Baldwin says, “because [barred owls] can be territorial.”
As for which trees work best? Bigger is better. “Because the bigger your tree is, the flatter it’s going to be, so the box can make more contact,” he notes.
Rather than donning tree-climbing spurs, Baldwin used a harness and ropes to climb my tree.
“We’re trying to limit the amount of damage we do to the tree,” he says. Being secured with ropes from above and from the side also enabled him to work hands-free. He explains, “You’ve got the nestbox. You’ve got hardware. You have the screwgun. If you’re on a ladder and you’re trying to hold onto the ladder and all this stuff, it’s nearly impossible.”
As he made his way up, Baldwin snipped off some of the invasive bittersweet vine that was clinging to my elm tree. This would help any owls taking up residence to have better visibility of the area below and to more easily hop on and off the limb closest to the owl house.
Baldwin secured the nestbox to the owl tree with a handful of lag bolts. Within minutes, a tiny pair of black-capped chickadees was investigating the cavity.
I’ll have to keep an eye out for squirrels and other uninvited guests—and I may need to be patient. In some cases, it can take up to a year or more for an owl to move in. Still, barred owls tend to be very opportunistic and, if conditions are right, they’ll readily accept manmade nestboxes.