A barred owl is seen sitting on a branch. Credit: Courtesy of Bob Duchesne

People often ask where I find the inspiration to write a different column every week. Sometimes I get inspiration from alert readers. For instance, I recently received mail, asking me to explain why owls are hooting in October.

My first answer is that they like to make Halloween spookier. Messing with humans makes them giggle. However, my second answer may be closer to the mark. Mating season has already begun.

Maine has three common nesting owls. One of them, the tiny northern saw-whet owl, generally leaves Maine during the coldest months. The other two don’t migrate. In fact, great horned and barred owls don’t even wander very much. They always have some notion of their territories, and are apt to proclaim it periodically. The hootin’ and hollerin’ starts in August, but intensifies in October.

Nesting season starts early. Baby owls must be able to hunt soon after they fledge. They must be fully developed by the time they leave the nest. This means that the owls have to start making babies early, since the youngsters spend a long time on the nest before departing. Barred owls sit on the eggs for about a month, then tend the nestlings for another month. For great horned owls, it takes even longer — 10 weeks or more before the chicks are ready to leave the nest. Once off the nest, barred owl chicks may stay in the area for up to half a year, before wandering off to make their fortunes elsewhere.

Great horned owls start nesting earliest, usually in late winter. Barred owls nest a little later. Both begin announcing territories in autumn, and not just for mating purposes. Competing owls don’t like to intrude on each other, lest a fight break out. By announcing their territories, they can stay out of each other’s way.

Owls hoot to attract mates, although that’s often a foregone conclusion. Great horned owls mate for life. Barred owls probably do. In the offseason, both mates remain in the same general area, although they don’t typically roost together. Barred owls are typically cavity nesters, though they sometimes use open nests. They identify a number of potential nesting sites within their territories, and may switch from year to year within the same area. Great horned owls will often reuse the same nest. Once the pairs reunite in connubial bliss, it doesn’t take long to set up housekeeping.

Another reason that owls nest early, especially great horned owls, is that they don’t build their own nests. They generally take over the nests of other large birds, such as great blue herons and red-tailed hawks. By the time the rightful owner returns to the nest in the spring, the owl is already on it.

Perhaps the better question is this: why do the owls quiet down in early summer? Because they’re busy. They’re sticking close to the nesting site. They’re feeding the kids. They’re not keen on announcing where the babies are, in case some predator might be listening. Great horned owls don’t have to worry about predators very much. They are so ferocious, not even eagles will mess with them. Only unattended nests are vulnerable. But barred owls must be a little more cautious. Great horned owls, some hawks and even raccoons can raid their nests.

Now that you’re eavesdropping on owls, let’s make sure you know who you’re snooping on. The hoot of a barred owl is famously described as “Who cooks for you? Who cooks for you-all?” It’s basically a nine-note phrase, though sometimes embellished with a few screeches and cat-calls. The great horned owl booms a deeper five-note phrase, often described as “Who’s awake? Me, too.”

Listen also for call and response. Owls often answer each other. Female voices are higher in pitch.

It’s not a total shock to see owls out in the daytime, especially in winter. When food is scarce, they may be forced to hunt in daylight. Sometimes, they’ll perch out in the morning just to warm up in the sun. However, they’re not likely to linger in daylight. Crows are apt to take exception and harass them. This mobbing behavior becomes more aggressive as crow nesting season approaches.

Of course, owls can also be aggressive as nesting season approaches, especially when they perceive that you’re the threat. A great horned owl defending its territory can get quite impatient with humans. Attacks by barred owls are rarer, but not unheard of. Hmmm. Maybe they really are making Halloween spookier.

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Bob Duchesne, Good Birding

Bob Duchesne serves as vice president of Maine Audubon’s Penobscot Valley Chapter. He developed the Maine Birding Trail, with information at mainebirdingtrail.com. He can be reached at duchesne@midmaine.com.