Thursday, April 23, 2020

Attract Great Horned Owls to your yard with nest box

This owl, the Great Horned Owl, is probably the most familiar of owls in North America. The deep resonant hooting on cold calm winter nights is familiar to many.

Great Horned Owls are widely distributed throughout North and South America. They are absent only from the Arctic tundra, parts of the Amazon Basin, and the pampas grasslands.

Nearly wherever you live in mainland United States you have Great Horned Owls near you.

Would you like to attract them to your yard more frequently? Read on!


Photo of a young Great Horned Owl on a branch
Fledgling Great Horned Owl
Photo by Greg Gillson

What makes your yard attractive to Great Horned Owls?


These large predators hunt by perching and waiting for prey to scurry by. Then they swoop in silently to attack. They thus need trees or poles for perching. They need some open rough grass or other open areas. They may be more common in second growth forests with edges and openings. But they are common from forests to farmlands to cities.

To attract Great Horned Owls to your yard requires that your property is large and has big trees and open space. It should also abut similar properties or undeveloped areas, woods, farmlands, or grasslands.

There may be good reasons not to attract Great Horned Owls into your yard, though. They are fierce predators. They will hunt small prey such as squirrels and mice. They will hunt larger prey such as rabbits, grouse, and skunks. They hunt and eat all other owls! They will hunt housecats and even small dogs, up to about 15 pounds. So make sure that this large owl will be welcome on your property before enticing them into becoming full time residents.

You can provide nest boxes and platforms to attract Great Horned Owls. I'll discuss that after discussing natural nests.

Peek-a-boo. Great Horned Owl in an old crow nest
Photo by Greg Gillson

Great Horned Owl nests in nature


Great Horned Owls use old hawk, magpie, and crow nests for their nests. They also nest in cliff crevices and derelict buildings and barns. Red-tailed Hawks, American Crows, and Common Ravens probably provide the most nests for Great Horned Owls. These widespread birds help the owl become equally widespread.

These owls may use an old nest as is, without adding anything. Or they may add bark, leaves, or down feathers. They may crush their own owl pellets to add material to the nest.

Courtship begins in winter. Pairs are often heard hooting in the night before the eggs are laid. Great Horned Owls nest from February to April in most places, to June in some locations.

The female lays 1-4 eggs. They take 30-37 days to incubate until they hatch. The young remain in the nest for another 42 days before they are ready to fledge, leaving the nest.

Old hawk and crow nests are rarely reused the next season. Raising young owls often damages the nest making it unusable the next season.

How do you find Great Horned Owl nests? In spring, before the leaves come out, check large trees along fence lines between agricultural fields. Check trees along creeks and rivers. Check trees at the edge of the woods. What do you look for? Old hawk and crow nests. Look for horns sticking up above old hawk nests, as in the photo above!


Here is a very interesting video on the hearing and eyesight of the Great Horned Owl. It explains why this bird is such an amazing hunter.


The Great Horned Owl nest box


You can create a nest for Great Horned Owls by building a wire cone lined with sticks to mimic the nest of a hawk. Here are the pdf nest plans from Nestwatch and the Cornell Lab.

You can also build a nest tray to attach to a tree trunk. Again, weave sticks together to imitate a crow or hawk nest. (Look at how the nest platform is made in the video below.) Add smaller twigs or straw and pack it down to make it firmer for the eggs.

I've even seen a Great Horned Owl using a large metal washtub in a tree as a nest!

These owls may nest in a very large box as long as the entrance "hole" is at least 12 inches high.

Great Horned Owl nest box dimensions


These owls usually use a nest with an open top. They may also nest in large boxes with one open side.

Great Horned Owl nest platform dimensions overview
  • Floor 22x22 inches
  • Side height 8 inches
  • No roof
  • 15-45 feet above the ground
Weave sticks and smaller twigs together to create a nest. You must fill in any larger holes or gaps between sticks. You don't want the eggs to fall down too far. The mother owl must turn the eggs over while incubating.

Great Horned Owl nest box placement


These owls like to have nest platforms in live trees from 15 to 45 feet above the ground. Place in hardwoods (not conifers) that are at least 12 inches in diameter.

You may also place nests in open-sided barns or under cover in similar buildings that aren't used much in the spring. But such buildings are better for Barn Owls. [Great Horned Owls will prey upon Barn Owls (and all other owls), so don't place nest boxes of Great Horned Owls together with any other owl houses.]

Great Horned Owls are used to nesting out in the open in late winter and early spring. Yes, even with snow on the nest! This means you don't have to worry about which direction the nest faces, as with other owl nest boxes.

Here is a video showing a nest platform attached to a tree with sticks woven into it to mimic a hawk or owl nest. The adult owl returns to the nest at time stamp 1:31. (Do I hear Steller's Jay, Hairy Woodpecker drumming, Townsend's Solitaire, and Mountain Chickadees?)


Nest box competitors and maintenance


Really, there aren't many nest competitors for nest sites. Great Horned Owls are likely to be able to drive off any intruder to the nest.

The only animal that is likely to attack a Great Horned Owl is another Great Horned Owl! If they eggs are left unattended a Common Raven might eat them. Fledglings leave the nest before they can fly well. These may be preyed upon by foxes, coyotes, or bobcat.

Young owls are most likely to die from starvation if there isn't enough food. Parents feed the largest and strongest baby first. Only if there is sufficient food and the parents are better hunters do all the young get fed and survive.

You may need to repair and weave the sticks of the nest every year. Or perhaps just add a few new sticks. Do this in early fall when the nest is not in use. As you can see from the above video, it's no work of art! A layer of wood chips underneath may provide some insulation from the cold that may penetrate up through the floor.



You may like: 5 common backyard owls



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