Happy Owl-o-ween! | WHO should fear owls in our backyards? (mice)

Happy Owl-o-ween! | WHO should fear owls in our backyards? (mice)

A Great Horned Owl watches for prey at sunset.

Owls are distinct birds with historic recognition by humans dating back over 30,000 years! These unique predators have been represented in various cultural mythos as carriers of messages, death, witchcraft, wisdom, evil, and mystery. Less mystical perceptions of owls often depict them as fearless, stubborn, and efficient. Hopefully, this owl-centric post can paint a new perception of the owl as an ecological and economic asset for humankind.

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The REAL best mousetrap

For those who have browsed the rodent-control aisle at the local home improvement store, twelve different “World’s Best Mousetrap” likely litter the shelves. And possibly, many of those “World’s Best” mouse eliminators are far from being the quality of rodent control needed to protect mankind’s assets from pest damage. Enter the silent-flying, night-seeing, other-worldly hearing, pest-killing owl.

As a method of rodent control, the owl often goes unnoticed. Perhaps it is advertising? Maybe it is not in the correct aisle of your local superstore. Likely, the answer lies in the timing of these creators of mass rodent destruction. Two of North America’s most prominent owls are mostly to strictly nocturnal, meaning they hunt their furry quarry when most humans are fast asleep, thinking minimally of their mouse problems. Of course, more than two of North America’s owls are nocturnal. In fact, of our approximately twenty regularly occurring owls, only five or six species are truly diurnal (active during daylight hours), leaving the majority of these silent predators to do rodent-dirty work at night. Luckily, this is when most rodents are active.

Most people have not attempted the feat of eating ten to twenty percent of their body weight in a day. Astonishingly, owls must regularly eat this much to maintain or make gains in their body mass. This feat is accomplished through the consumption of a significant amount of small mammals, from mice and voles to rats and rabbits. How many might they consume? A lone Great Horned Owl will eat around seventy grams of animal matter each day, which is about three to four mice or one to two hefty rats. However, a Great Horned can consume much more during periods of higher energy needs. For example, a single nestling Great Horned Owl will consume between 200 to 400 grams of animal matter each day, or approximately ten to FORTY mice. While a math lesson is not the primary goal of this article, consider the impact of raising THREE Great Horned Owl chicks by two adults.



An Adult Great Horned Owls eats 3 mice per day

A Nestling Great Horned Owl eat 20 mice per day

Incubation is around 33 days

Time to fledging is around 46 days

There are two adults

There are three nestlings



2 adults X 3 mice X 33 days = 198 mice eaten during incubation

2 adults X 3 mice X 46 days = 276 mice eaten during nestling growth

3 nestlings X 20 mice X 46 days = 2,760 mice eaten by nestlings



3,234 CONSUMED MICE: A hefty potential rodent control!


While these are rough estimates and will vary by nest, time of year, and prey availability, the result still shows that a nest of Great Horned Owls has the capability of eliminating over 3,000 mice during a nesting period. Of course, Great Horned Owls consume more than mice, and some more oversized prey items will likely be consumed. Owls are truly capable of being a mousetrap unmatched by anything baited with a bit of swiss.

A baby Great Horned Owl sits outside of its nest.
A baby Great Horned Owl recently left its nest.

A better backyard clean-up

Keeping the ground clean under a feeder is a challenging and time-consuming task. Raking or sweeping up hulls and the uneaten seed will help mitigate nocturnal pests from being attracted to your yard, but there is no guaranteed way to prevent a rodent incursion! Rodenticides are dangerous to humans, pets, and wildlife; spring traps are often ineffective; live traps are time-consuming; those noise-making deterrents are nearly worthless outside; and outdoor cats will eliminate the reason for feeders! What is a backyard bird feeder to do? The answer is above. Owls. Create a backyard that is welcoming to the apex mouse controller.

Great Horned Owls are one of the most common species found throughout the Western Hemisphere, but there are countless other owls capable of wreaking havoc on your backyard pests! Barn Owls, screech-owls, Northern Saw-whet Owls, and Barred Owls are all found in various habitats and are all attracted to spaces created with their comforts in mind! Maintain mature trees, minimize the noise in backyards, avoid pesticides and rodenticides, and hang a proper nest box, and an owl is likely to consider becoming the newest neighbor on the block!

Support local owls

Learn more about which owls might be found in backyards, what attracts them, and how to create a suitable nestbox. Support your local owls, and they will support you in return.

Eastern Screech-Owl

Range: The Eastern Screech-Owl is found throughout the eastern United States, almost anywhere east of the Rockies and south of the Canada border. Southeast Canada hosts some Eastern Screech-Owls, and their range is likely to continue expanding.

Habitat: Prefers mature deciduous or mixed forest, but patch size is not as important as the presence of a nesting and/or roosting cavity.

Diet: The Eastern Screech-Owl eats mostly mammals, birds, and invertebrates, but rodents and birds make up most of the biomass eaten.

Nest box: D 17 ⅜ inches x L 9 ⅝ inches X W 11 ¼ inches with an entrance hole of 3 inches X 4 inches

An Eastern Screech-owl looks sleepy.
Screech-owls can be difficult to distinguish.

Western Screech-Owl

Range: Most states and provinces of the Rockies and west to the coast. The Western Screech-Owl is found up the Pacific Coast to southern Alaska.

Habitat: Prefers riparian habitat or habitat with mature deciduous trees. As with the Eastern Screech-Owl, this owl uses cavities for roosting and nesting.

Diet: Eats a large number of invertebrates, mammals, and birds. Diet varies with season and location.

Nestbox: D 17 ⅜ inches x L 9 ⅝ inches X W 11 ¼ inches with an entrance hole of 3 inches X 4 inches

Barn Owl 

Range: The Barn Owl is common across the western United States, southern United States, and eastern United States, and less common throughout the rest of the country and a few locales in southern Canada.

Habitat: The habitat of the Barn Owl varies by location, but as their name suggests, they will utilize human structures (including nest boxes).

Diet: The majority of the diet of the Barn Owl is small mammals.

Nest box: D 16 inches x L 12 ⅜ inches X W 22 ¾ inches with an entrance hole of W 4 ½ inches X H 3 ¾ inches

Barred Owl

Range: The Range of the Barred Owl is expanding but can currently be found east of the Great Plains, in the Pacific Northwest, and a few distinct locations in central, western, and southern Canada.

Habitat: Prefers mature, old-growth forests in more significant swaths.

Diet: The largest percentage of the Barred Owl’s diet consists of mammals; however, this owl eats various prey items.

Nest box: D 23 inches x L 13inches X W 13 inches with an entrance hole of diameter 7 inches

Northern Saw-whet Owl

Range: This small owl is found throughout the boreal forests of Canada and Alaska, south into the central US, and along the Rocky Mountains and Pacific Coast.

Habitat: This owl can be found in many forest types and will roost in dense thickets or cavities. It nests in natural or manmade cavities.

Diet: Mice and voles make up the primary element of this owl’s diet, with birds and invertebrates rounding out the preferred foods taken.

Nest box: D 17 ⅜ inches x L 9 ⅝ inches X W 11 ¼ inches with an entrance hole of 3 inches X 4 inches

Close-up of a Northern Saw-whet Owl.
Do not be fooled. This is a vicious predator.