Step out into the cool night air and listen for the owls calling.
Now is as good a time as any, with the great horned owls on territory all year round, and typically issuing their announcements of the fact with increasing frequency as the season we call winter approaches. The deeper hoots of the males are joined in duet by the higher-pitched voices of their mates as the pair begins to associate more closely after a period of less intimate neighborhood.
It takes some time to raise owl chicks—a month of incubation, nearly two until they fledge, and perhaps another four beyond that first flight until they are fully independent. Seven months or more from egg laying until a still uncertain maturity is achieved means that great horns might establish their nest sites in December, well before the songbirds who see their young go from egg to independence in two months. Most birds wait for the days to lengthen to begin their nesting process. But owls start when the night is at its longest, for they do not fear the darkness or the chill of stinted sunlight.
Growing daylength is the primary trigger for birds’ nesting and the migration that might precede it. But for the great horned owls, it is the longer nightlength that awakens their haunting winter music.
Hunters: The Implacable Grasp
Great horns are by far our most widespread and commonly encountered owl species. There are numerous other owls in California, but most are found in wilder habitats, whether the open fields and wetland edges favored by the barn owls or the woods and forests of the screech, pygmy, and spotted owls. Great horns are more versatile generalists and are found in most places outside of the furthest extremes of treeless plains and thickest forests, including most residential areas.
They eat a great diversity of prey, mostly small mammals, but with significant additions of birds, insects, reptiles, or whatever else is convenient and abundant in the area. A wide base of prey means that great horned owls are well-equipped to survive all year round in one location without the need for migration. Their flexibility in feeding is matched by their flexibility in nesting, finding suitable accommodations in a wide variety of locations, most commonly in abandoned or usurped nests of hawks or ravens, but also in cliffs, broken-off tree snags, or a number of quirkier settings depending on what an area offers.
Of all our birds, this is the fiercest. This is not just a function of size. Yes, their 3.5 pound weight is substantial for a bird. But they have been known to kill and eat adult great blue herons (5 lbs.) and bald eagles (9 lbs.). They will eat seven-pound skunks, disregarding the spray. They will eat fifteen-pound porcupines, disregarding the quills. They will eat their siblings in the nest and adult rivals who invade their territory. Small animals they swallow whole. For larger prey, their distinctive technique is decapitation, a touchstone of historical and fantasy warfare when one side aims to warn and intimidate. This isn’t their conscious intention here, but should I discover a beheaded cat, intimidated I will be.
The primary hunting style of great horned owls is perch and pounce. In comparison with some other species, their wings are relatively small compared to their bodyweight, making them fairly adept at maneuvering among trees, but poor at efficiently coursing over fields for an extended period. Some birds evolved towards ever lighter weight and increased efficiency; great horned owls evolved towards strength. Long-eared owls possess a respectable three-foot wingspan compared to the three-and-a-half of great horns. But the talon strength of long-ears was measured as requiring 1,350 grams of force to open, while great horns measured in at 13,000 grams. When they take hold, they don’t let go.
The result of unparalleled ferocity and undiscriminating predation is widespread fear and animosity. Most noticeable of the owls’ opponents are the smart talkers, the crows, who will band together to drive out an owl whenever they discover one. But most birds, down to little hummingbirds, will join in the mutual defense known as mobbing, the attack of predators by smaller birds that are not being immediately threatened. The proximate goal of mobbing is to drive the predator away, often not through any plausible threat to its life, but rather through annoyance and discomfort. In the long run, mobbing has evolved as a common bird behavior because it reduces predation risk. The attacks of hummingbirds and crows alike is a testament to the great horns’ universal threat.
In the day, they can be outnumbered and harassed. But at night, they have no fears. Not like us: we evolved to fear the dark and the strange voices somewhere out there. Now we think that we’re protected, by our walls, lights, and technology. We’ve killed off the grizzlies, driven out the wolves, and pushed the mountain lions to a furtive existence. But if a part of wildness is that vague and ancient fear of the dangers of the dark, then we can still hear those terrors calling in this voice outside our window.
We can listen and shed our reasoned safety. We can reach deep into our body’s memories, the memories of instinct and of prey. And when we see that great horned head swivel towards us in the shadows, catching moonlight on those giant eyes, we know that we are being watched and it is not the bird who feels afraid.
Watchers: To See Through Evening’s Shadows
Even if you’ve rarely or never seen them, great horned owls are not hard to encounter or to recognize. Within our neighborhoods, this species is the sole author of the classic owl sound for which we’ve invented the universally recognized term of “hooting.” And if you should see one, their name provides the easy clues to identification. “Great” is appropriate for the clearly largest of our local owls. And the horns or “ear tufts” of these birds are usually distinctive, perky protruding feathers thought to mimic broken branches and so disguise their body’s outline and enhance their daytime camouflage. (They have nothing to do with either devilry or hearing.)
Great horned owls are not difficult to distinguish from other owls, with these few bits of information. But almost everyone can recognize an owl without being given any bits of information, because the group as a whole possesses a number of highly distinctive adaptations for their highly unusual lifestyle compared to other birds. The key undercurrent running through owl physiology, of course, is that they conduct the business of their lives in the condition we call darkness.
When we go outside at night, we feel an immediate loss of effectiveness: we can no longer see, no longer obtain the crucial information we rely on in the day to make our practical decisions. Birds likewise rely on vision to find food, fight, or flee. And so it is that owl eyes are significantly larger than those of most birds, to allow the capture of more light. Even at a glance, the eyes of a great horned owl look large, but the proportional extremity of this development is easy to overlook: owls have been measured with their eyes weighing in at 32% of their skull weight, while human eyes are about 1%.1
Some of their ocular adaptations have trade-offs: they are large and forward-facing, to give better depth perception, but at the cost of the wide peripheral vision of most birds with eyes more on the sides of their head. Owls are less worried about lateral sneak attacks and more concerned with getting the most accurate positioning of their target. Likewise, they have discarded the sensitivity to the ultraviolet part of the spectrum which is common among most birds: the world of night is not one of fine colors. Even for them, the nocturnal world is made of shadows. But what they see by scattered starlight, we would need a full moon to tell, and when that moon is shining, then the owls’ sun has risen.
The moon, of course, doesn’t have the sun’s daily consistency. One of the great losses of our electrified lives is our poor awareness of the moon’s nightly shifting appearance. I love to read the old poems, in which Li Bai sees the moonlight shining before his bed and thinks it must be frost, or Wang Wei plays his qin in the bamboo grove and feels himself alone “until the moon looks down,” or Han Shan sits on into the night, mouthing sutras in the silver glow. There is beauty in the softer light as there is in quiet music. I reach back into the past and catch a faintest touch of what’s almost been forgotten.
But an owl knows far better each rung that climbs up from the darkness. Not just the incandescent glare and its cold, forbidding absence, nor even the twilight and the noonlight, but each fine and precious sliver of the slowly waxing moon.
Listeners: The Sense That Knows No Darkness
The variability of the moon suggests the limits of relying on that light alone for one’s survival. Fortunately, there are other senses, the most important of which is hearing. Owls do not echolocate to the extent of replacing their vision, like bats or certain swiftlets, but their hearing is significantly more acute than ours, and is vital to their success.
Upon discovering a perched Short-eared Owl the length of a football field away, it is instructive to pucker up and suck in one’s breath sharply. This will produce a sound similar to the soft squeak of a mouse and cause the owl’s head to whip around at once to face the squeaker. A captive Northern Saw-whet Owl busy eating in a noisy room, with people talking and the television turned on, instantly stopped and stared fixedly at a distant corner of the ceiling whence came the faint rasping sounds of a mouse gnawing.
– Hans Peeters, Field Guide to Owls of California and the West
It’s illuminating to actually play out those scenarios in your mind. Owls can see in the dark more effectively than we can, but their powers of hearing are more important still. Of all the strange and wonderful things there are to imagine about the lives of owls, I think this is what most captures my imagination: the knowledge that they are always listening and can hear the subtle music that is just beyond my reach.
Listening is my favorite pastime. Sometimes it starts pragmatically enough—trying to hear and identify the different birds, for instance. But when you develop a habit of listening closer and closer, you can’t help but notice more. You notice the fine qualities, the minute gradations of tone and timbre, the magic of each voice. You notice the silence, and within it the faint and far off whispers that were previously drowned out by the mere scurrying of your thoughts.
But no matter how intently I focus, no matter how patiently I still my body and quiet my breathing until I can hear the gentle pulsing of my blood, I can’t sufficiently enwrap myself in silence to match the hearing of the owls. And when I move I spoil everything, with clothes rustling, inhalations coming louder, and every footfall a blaring announcement of my presence that overwhelms my own ability to hear.
To be a virtuoso listener is to also master silence. Owls have unique velvety feathers that let them fly in utter quietness. After years of practice at this birding business, I’ve learned to snap my head around at the slightest flapping or distant whistles from the sky. Alertness to sounds is the key to finding birds. But all my instincts and my skills are useless when it comes to owls, even this largest one, even right over my head. I never hear her coming, but am suddenly surprised by that unannounced appearance.
Even more important than sneaking up on prey or birders who thought that they were hotshot listeners, this ability of silent flight lets owls listen without interruption by the passage of air over their own bodies. Soft facial feathers surround their ear cavities like those fluffy things outdoor film crews put on their microphones to muffle wind noise. Imagine running down the street, unsheathing your weapons as you prepare to strike, and all the while maintaining a silence so deep that you can hear your target’s breathing. That’s what the owls do.
To see like an owl would be an extraordinary thing, to observe the impenetrable patches of darkness transformed into visible landscapes beneath a moon of tripled brightness. But if I could lift the human veil that sets the limit on any of my organs, I would choose the owls’ hearing and listen to the faintest voices. I would know the authors of the nighttime sounds, their size and their positions, their chewing on a fallen seed or their step that breaks a brittle leaf. Every evening I would listen wrapped in a perfect silence, my airy feathers damping every whistle of the wind.
Singers: A Song No Longer Unrequited
This is my music each evening.
– Thoreau, The Journal, November 18, 1851
The song of the great horned owl is our most widely recognized nocturnal sound. We’ve invented a word for it, “hooting,” that everyone can accurately associate with owls, even if they don’t know the exact species name and have never seen one in their lives. From there, it’s just a small step to establish a more comprehensive familiarity with this sound’s patterns and meanings.
Only great horns give the deep, sonorous hoots that you hear around your neighborhood. There is a limited amount of variation in the number of syllables, affected by the sex, mood, and personal inclinations of the individual owl, but the tone and pattern are quite consistent. Most songs have between four and seven notes in total, all on essentially the same pitch. A common five-syllable format might look like:
Hoo, hooHOO… HOO HOO
The introductory hoot(s) may vary in number, or sometimes be replaced by sharper barks. Then the longer, doubled and stutteringly accented note (hooHOO) follows. Almost all renditions end with a brief pause and then two well-spaced hoots. Although the classic hooting is a consistently recognizable sound, be aware that great horned owls also perform assorted other barks and shrieks, with subtleties somewhat beyond our knowledge dividing them into subgenres of agitation, defense, courtship, and begging.
For most practical purposes you shouldn’t get great horned owls mixed up with any other birds. The biologically quite distant barn owl gives drawn-out, ringwraith screeches, while the little woodland screech-owls perform higher-pitched, accelerating, “bouncing ball” trills. In Marin’s forests, you might hear spotted owls (a kind of hooting, but a more yelpy and barky kind of sound, with a different cadence than the distinctive great horn pattern) or pygmy owls (single, widely spaced toots), but neither of those birds is likely to be encountered in typical residential neighborhoods.
You can hear great horned hooting occasionally at any time of year, but it does become more prominent during the preliminary stages of nesting, as with birdsong in general. Hooting is also like other birdsong in that it is dominated by the contributions of the males, who are more vociferous in their territorial declarations and defense. (Males without territories, often younger birds, live a life of silent floating until they are ready to wage war both aural and entaloned.)
What is more unique to great horned hooting is that it also involves frequent duets between the male and female as the nesting season approaches. One bird begins to sing, and the second then joins in within a few seconds, with hooting phrases either alternating or overlapping. You can easily distinguish the higher-pitched female voice from the lower voice of the male within these shared performances. Such duets are relatively rare in the bird world, but are a way of reinforcing pair bonds that is most often found among species that are non-migratory and have long-term mates, a category that includes great horned owls as well as a few local songbirds like wrentits and brown chippies.
Although we rarely get a chance to see the full range of courtship and pair-maintenance activities of owls, the same general tendency applies with these birds as with the small, daytime species I’ve discussed before: the plain birds that stick together often engage in more complex shared behaviors compared to the merely pretty ones who rely on color or elaborate male songs to attract a new mate each spring. Duets are the most easily observed example, but great horns’ physical displays of bowing and tail-bobbing are likewise reciprocal (though males do give a few extra vigorous fluffs of their white collars) and both sexes participate in the classic activities of avian affection such as bill-rubbing and mutual preening. Some behaviors are a bit more idiosyncratic to owls’ unique blend of the ridiculous and the terrifying: “courting pairs indulge in high-pitched giggling, screaming, and bill-snapping” reports one study. 2
The female’s specific expectations of her partner consequently go beyond the surface displays of goldfinches or hummingbirds to ongoing substantive performance: most notably the exclusion of other owls from the territory and continual provisioning of food throughout her several weeks of incubation and brooding. The fairly uniform hooting of an owl is not primarily intended to impress the female: she has already chosen him as the warden of her borders, a duty that he now fulfills. Hooting primarily announces territory, declarations in which she will eventually join her partner, to his great satisfaction.
Duets are not the songs of those who court, but of those who long have been together. As their children grow independent, the couple will grow apart and spend more time alone, but now in autumn the female again tolerates her mate’s approach. Now the intermittent, tentative declarations that he gave even in July or in September find their meaning and their purpose. His hooting once unanswered now receives that higher echo. He no longer sings alone and his voice grows sure and certain. All his fierceness, all those deep-voiced challenges—now he remembers what they were for. He sang alone till nights grew cold. Now she joins her song with his and the cold nights cannot touch him.
Header photo by Tom Wilberding.
- Peeters 2007, Field Guide to Owls of California and the West, citing Korbel 1998, “Erkrankungen des Augenhintergrundes bei Greifvögel.”
- Artuso, C., C. S. Houston, D. G. Smith, and C. Rohner 2020, “Great Horned Owl (Bubo virginianus)” in Birds of the World, citing Voous, K. H. 1988, “Owls of the Northern Hemisphere.”
Hi Jack, has anyone dubbed you the Naturalist Bard of Novato? I recently discovered your posts, and am impressed and inspired, to say the least. Thank you for this poetic & thorough exploration of owls, who (ha) I have indeed been hearing lately.
I was hoping to shoot you a question or two about oaks; I’ll do that via the contact page. Thanks again! Francesca in Petaluma
Thank you Francesca! I have not been thus dubbed yet, but it sounds like a worthy title to aspire to! I didn’t see any oak questions come through, so feel free to resend those.
What a wondrous, extra-sensory exploration of these magnificent neighbors of the night – once again, thank you, Jack! And the fabulous photos – in particular, the black & white by Carolyn Whitson: bravo!
Thank you Chris! Yes, I put that black and white one at the end because it was my favorite too.
He sang alone till nights grew cold.
Now she joins her song with his and the cold nights cannot touch him….so cool!
Thank you for sharing this. I often hear the owls at night, and now I have a lot more to consider.
Lovely.
Great content! Keep up the good work!