ON SILENT WINGS: The Owls of Santa Clara County

ON SILENT WINGS

The Owls of Santa Clara County

by Julie Amato 


Owls! Throughout history, we have been fascinated and awed by these beautiful creatures of the night. With near-magical powers to see in the dark, and faces that eerily resemble our own, these birds are some of the most charismatic animals in the world.

Nine owl species have been documented in Santa Clara County, but only three are widespread: the American Barn Owl, the Great Horned Owl, and the Western Screech-Owl. All three of these owls are year-round residents of our area and nest here.

Read on to learn more about these birds and how you can help them, and enjoy stories and images of Bay Area owls contributed by our members and friends.

But first - what makes owls so special?

Great Horned Owl by Rick Morris. Note the bird’s large eyes and “ear tufts,” which aren’t ears, but patches of feathers!

Owls are consummate hunters, able to catch live prey in the dead of night.  How are they able to do this?

First, owls have BIG eyes. The Great Horned Owl’s eyes are enormous - together, they are about the size of its brain! If our eyes were proportionately the same as an owl’s, they would be as big as oranges.

Owl eyes are also structured differently than ours - they have many more rods in their retinas than we do, which allow them to see well in low-light conditions. And they have excellent binocular (forward-facing) and peripheral (sideways) vision, a useful adaptation for a predator. By contrast, humans have good binocular vision but a much more limited range of peripheral vision.

Owls also have keen hearing, which they can use to pinpoint prey. The Great Gray Owl can hunt rodents buried under more than a foot of snow, just by listening! Owls’ ear openings may be offset, allowing them to locate the position of a sound more quickly than we can.

In fact, an owl’s entire face is part of its hearing apparatus. The circle of feathers surrounding its eyes and bill, the “facial disc,” acts like a parabolic reflector, directing sound towards the owl’s ears. Through movement, an owl can temporarily change the shape of the disc to focus on particular sounds.

And don’t be fooled - those feathers that stick up on either side of some owls’ heads, often called “ear tufts,” aren’t actually ears! They are fluffs of feathers that owls can raise, lower, and move around, presumably to communicate with each other. Their actual ears are openings hidden under the feathers on their heads.

American Barn Owl in flight by Doug Beattie

Finally, owls have near-silent flight, allowing them to take their prey by surprise. This silence is achieved by large, wide wings, which allow them to fly slowly, and a feather structure that reduces air turbulence - owls’ wing feathers have a serrated leading edge and a fringed trailing edge. Their wing feathers are also softer than other birds’, reducing friction when the feathers move against each other. 

Great Horned Owl with prey by Teresa Cheng

Owls hunt mostly at night but can be active during the day too, especially if they need to find food for their young. They have a wide-ranging diet, including mammals, birds, fish, reptiles, amphibians, and insects. The American Barn Owl and the Great Horned Owl eat mostly mammals. The Western Screech-Owl has a varied diet based on the habitat and season. The size of the prey is generally relative to the size of the owl.

Great Horned Owl juvenile by Doug Beattie. This young bird is eating a meal brought to it by a parent.

Meet the common owls of Santa Clara County

American Barn Owl by Rick Morris. Note the white heart-shaped face and dark eyes, making it distinct from the other owls of our area.

American Barn Owl (Tyto furcata)

The American Barn Owl has a white heart-shaped face, a long pale bill, and dark eyes. Its back and wings are different shades of brown, buffy orange, gray, and white. Underneath, the birds are often completely white, although some have colored feathers, and some have beautiful small spots on their breast that look like stars. The birds have long, pale, feathered legs that trail behind their bodies in flight. About the size of a crow, this owl is smaller than a Great Horned Owl and bigger than a Western Screech-Owl.

American Barn Owl by Teresa Cheng. This bird is a beautiful mosaic of brown, orange, buff, gray, and white colors. Note the starry spots on this bird’s breast, which are found on some of these owls.

In Santa Clara County, American Barn Owls are our most widespread owl, found in a diverse range of habitats. The birds like open areas - grasslands, farms, and marshes - but also urban spaces. They are a common backyard bird, although many people don’t know this because the owls are active at night! As cavity nesters, their natural nest sites are in trees or cliffs, but they also nest in buildings and other man-made structures, including nest boxes and, yes, barns.

Great Horned Owl by Doug Beattie. These are big birds! Note the yellow eyes and large “ear tufts.” Their black, brown, gray and white feathers allow these owls to blend seamlessly into their surroundings.

Great Horned Owl (Bubo virginianus)

This bird lives up to its name! The Great Horned Owl is one of the tallest, heaviest owls in North America. A bit bigger than a house cat (to which it has a strong facial resemblance), and weighing as much as a half gallon of milk or more, it is the largest owl found in our county.

The Great Horned Owl has yellow eyes and a black bill in a brown or gray face. Its ear tufts or “horns” are large, and can be tucked down and flattened against the head too. This bird has intricately-mottled brown, cinnamon, gray, and white plumage, allowing it to blend in with the trees.

Great Horned Owls by Julie MacKinnon. This image shows a parent (far left) with two of its offspring. Young Great Horned Owls have fluffy white down on their faces and heads which they gradually lose as they mature.

Like American Barn Owls, Great Horned Owls like open spaces, but they are also found in woods, forests, and residential neighborhoods. Also widespread in Santa Clara County, they are observed more often in the western and eastern foothills and adjacent areas. The birds are opportunistic nesters and will often use tree nests built by other birds, like hawks. They also nest in natural cavities, on human structures, and even on the ground.

Western Screech-Owl by Rick Morris. This owl is roosting inside of a building!

Western Screech-Owl (Megascops kennicottii)

This small owl - about the height of a field guide to birds! - has yellow eyes and a tiny black bill. Like the much larger Great Horned Owl, it has ear tufts that it can raise and lower.  

The Western Screech-Owl has feathers in a variety of colors, but overall, the bird has a fairly uniform appearance - gray, brown, or even red - with long dark streaks running down its body, making it a perfect match for the bark and branches of trees. The owl is related to the similar-looking Eastern Screech-Owl (Megascops asio), which is found in North America east of the Rocky Mountains.

Western Screech-Owl by a Milpitas birder. Note how the bird’s plumage colors and pattern perfectly camouflage it among the trees.

In our area, Western Screech-Owls prefer oak woodlands. These birds can be found in the foothills and nearby areas, and are common in the Santa Cruz Mountains. They are also in residential neighborhoods with suitable habitat. They are cavity nesters, and will nest in woodpecker holes, natural holes in trees, and nest boxes.

American Barn Owl by a Milpitas birder. Find the bird! Since owls are masters of disguise, and most active at night, you are far more likely to hear one of these birds than see one. 

Listen for owl calls at night

While it is always a thrill to see an owl, you are much more likely to hear one. With our limited night vision, it’s hard for us to spot one of these birds in the dark, but our hearing is still acute.

Owls make a wide variety of sounds, but here are the iconic calls that will help you identify them:

The American Barn Owl’s typical call is dramatic, sounding like a scream straight out of a horror movie! The call is a single long rasping screech. When the bird is nearby, the effect is loud and startling. It often makes this call while flying.

The Great Horned Owl’s call is also cinematic, the stereotypical owl call of Hollywood films. This bird hoots: “hoo-hoo-hoo-hoooo-hoooo!” Sometimes, a male and female will call back and forth to each other; this is called “duetting.”   

Curt Bianchi made this recording of a Great Horned Owl duet near his home in Saratoga:

The Western Screech-Owl, despite its name, does not screech! It is known for its “bouncing ball” call, a series of soft rapid hoots that accelerate towards the end, like a ball in motion releasing the last of its energy.

American Barn Owls by Teresa Cheng. You can build and install a nest box for these birds in your yard.

How you can help owls

Like all birds, owls are sensitive to human activity. In addition, because we are so attracted to these birds, it is possible to give them too much attention, disrupting their lives in ways both small and large.

Here is how you can give owls a helping hand:

Be an ethical, responsible owl observer. Use your eyes and ears to find owls - never bait them or lure them in. If you’re taking pictures, don’t use your flash; owls’ eyes are far more sensitive to light than ours and you can temporarily blind them.  

When sharing your owl stories and photos with others, consider the birds’ welfare first, and be thoughtful about sharing location information. Birds that receive a lot of attention may be disturbed by it, imperiling their survival and reproduction. 

Stop using poisons in your yard. Owls and other raptors often hunt rodents in residential neighborhoods. If an owl eats a poisoned rat, the owl is poisoned as well. Consider environmentally-friendly and humane alternatives to managing rodents. Owls provide excellent rodent control for free!

Turn off outdoor lights at night. Artificial light at night disrupts biological processes and can disturb owls because of their highly sensitive vision. The blue spectrum of LED lights is particularly confusing for animals that are active at night, since it is similar to daylight. 

Western Screech-Owl in a tree cavity by a Milpitas birder. By leaving dead trees in your yard, you can provide habitat to birds that nest and roost in cavities.

Leave dead trees in the landscape. Many owls are cavity nesters, which means that they make nests in holes and crevices. Birds often excavate cavities in dead or dying trees, making these trees a valuable part of the ecosystem. If you have a dead tree in your yard, consider leaving it in place if it’s safe to do so.

Build a nest box for an owl. American Barn Owls and Western Screech-Owls use nest boxes, artificial structures that mimic natural cavities. You can build and install one of these boxes in your yard - see our resource section below for plans.

Burrowing Owl by Sreedhara Alavattam

Support owl conservation initiatives. The Burrowing Owl, an iconic species, is declining in the Bay Area. Together with other conservation groups, the Santa Clara Valley Bird Alliance has petitioned the State of California to list our local Burrowing Owls as endangered.

You can join us in speaking up for the protection of these birds. See our resource section below to learn more and get involved.

Owl stories from our members and friends

If you’ve ever seen or heard an owl, chances are that you still remember the moment!  

Enjoy these stories and images of Bay Area owls shared by our members and friends.

Vicki says:  “It has been such a delight to host this adorable Western Screech-Owl for the past three years from fall to spring. I first noticed it in our second-story eaves in the fall of 2021. I was looking through binoculars scouting for insect nests before putting up a ladder to do some roof work. At first I thought it was a hornet's nest and was quite startled when the 'nest' opened its eyes and stared down at me!”

The Western Screech-Owl that roosts under the eaves of Vicki’s home

“It is there all day long during the rainy season. I have never heard it call and I only saw it fly twice - a silent, graceful take-off at dusk from the downspout just next to the eave. It must be a successful hunter because I have noticed a decrease in the rodent population since its arrival. In early spring it disappears and doesn't return until the following rainy season. I hope it decides to return once again in the coming months.”

Hugh McDevitt (San Jose) told us: “My wife and I often take early evening walks near our home. One evening in June, my wife saw a large owl fly across the road and land in a creekside tree. A couple of nights later, we heard some owls vocalizing and went to investigate: we saw four owls perched on branches reaching over the creek, Great Horned Owls - one adult and three fluffy juveniles.”

“Over the next two weeks, we saw the owl family in the same location. We also watched the three juveniles - all perched on the spark arrestor of a nearby home - and the adult flying over the area and perching in a tall juniper tree. We continued to hear them for at least a month flying over our neighborhood. While we often see American Barn Owls flying over our house, this was our first encounter with Great Horned Owls near home.”

A Great Horned Owl spotted by a Milpitas birder

A birder in Milpitas says: “I live close to the eastern foothills which are where I have had most of my owl sightings. Great Horned Owls also come to my neighborhood often in the fall and winter. I just heard them at 5 AM recently. Two of them can duet for up to fifteen minutes at night.”

“I have seen Great Horned Owls perched on a power pole or out catching squirrels in the spring at noon, probably getting food for young ones. When I go hiking, I can hear them calling in the dense woods surrounding the hills.”  

A Northern Pygmy-Owl with prey, spotted by a Milpitas birder. These tiny owls can catch prey that is much bigger than themselves!

The birder continues: “Last spring, I stumbled upon an adult and a juvenile Northern Pygmy-Owl when biking on a trail. At first, I was surprised to see hummingbirds and woodpeckers and titmice surrounding and harassing something very tiny. It was a pygmy-owl no larger than an Acorn Woodpecker! The owl was young and inexperienced and perched in the open on a bare tree. The parent was hidden in a tree nearby that was full of leaves.”   

Curt Bianchi (Saratoga) says: “At our house in suburbia, we often hear Great Horned Owls at night, hooting so loudly that they must be in our trees or those of our neighbors. But I had no idea that we also had Western Screech-Owls here until I checked my bird bath camera one day and discovered this video from the previous night.”

Western Screech-Owls visiting Curt’s yard

“You can see that a Western Screech-Owl has perched on our bird bath, and that there is an owl or two fluttering around in the background. One of my best videos from our bird bath! I have often thought we should get a bigger one, but this little bird bath has hosted owls, hawks, woodpeckers, warblers, orioles, and all the rest of the regular visitors in the neighborhood. So I guess it’s good enough!”

Steve McHenry and Carolyn Straub (San Jose) told us that “an owl with an odd-seeming song was heard in the wee hours of October 13 by Steve while he was camping.”  

Steve says, “It screamed and squawked for a long time, several minutes, before it finally trailed off with the bouncing ball call. That was why I could not figure out what it was until the very end. It was close by, and very loud, so I heard it well. It was loud enough to wake me up! It called two or three times, a couple of minutes each time, with quiet in between. It was only when it called for the last time that I recognized the owl for what it was.” The bird was a Western Screech-Owl, known for its “bouncing ball” call.

LC Boros (San Jose) writes: “We run several audio recorders at various locations here at the ranch, and they regularly pick up a variety of owls.”

American Barn Owls sometimes nest in LC’s barn. Here is one of the owl families that LC has hosted.

“There are times we’ve had American Barn Owl clutches in the old barn.”

A timelapse video of American Barn Owls nesting in LC’s barn

An owl pellet spotted by LC at her home. 

LC adds: “There is the daily issue of walking outside and dodging owl pellets.” Owls regurgitate the parts of their prey that they can’t digest, like bones, fur, and feathers. These parts form a mass called a “pellet,” which is expelled by the owl. If you find a pellet, there is most likely an owl somewhere nearby!

A Great Horned Owl at LC’s ranch at dusk

Francesca Kukralová (Santa Clara) says: “My family and I went out of town to escape the recent heat wave, and in the evening, as we were starting to head back home, we swiftly pulled over by the side of the road near a field because I had spotted a large Great Horned Owl standing on a power line, only a silhouette but with the ear tufts clearly visible. We got out of the car to have a better look and found that there were two owls, one on the power line and another standing on the pole.”

“The birds were making hissing calls at one another - not the classic hooting that I normally associate with Great Horned Owls. After hissing back and forth for a bit, the owl on the wire swooped down into the field. The other owl flapped off and landed in a nearby tree, and soon afterwards, the one from the field flew back out and joined the one in the tree.”

“When I got home, I tried to read up about Great Horned Owl vocalizations - specifically, what that hissing was all about. Oddly, I wasn't able to find much about hissing. It didn't sound like the begging call of a young owl, which sounds more like a screech than a hiss to me; besides, both of them were pretty big, and also they were both making this hissing sound at each other, rather than just one of them doing it. I did read somewhere that hissing can be done in courtship...maybe they were two courting owls?”

The juvenile Western Screech-Owl observed by Alden. This young bird has loose, fluffy feathers and thin horizontal barring.

Alden Hughes (Saratoga) shared this story with us a couple of years ago: “We hadn’t heard any owls over the nesting season, but at the end of June I noticed something odd on the fence outside my room.”

“This juvenile Western Screech-Owl was on the fence for at least five hours. It opened its eyes and stared at us through the window as we crouched behind the bed with my camera. Earlier in the day my mom had heard a racket of bushtits which could’ve been mobbing it, and a few hours after it was spotted it was mobbed again by finches and juncos, the seed feeders being only ten feet away, and flew to the ground before returning to its perch. It disappeared before sunset and no owls were heard for a week until we heard screech-owls after midnight for the first time in a while.”

Deanne’s nocturnal backyard visitor

Deanne Tucker (Los Altos) tells us:  “In October, we saw a Great Horned Owl in our fountain shortly after dark. I got a cellphone shot of it that isn't great, but you can tell what it is. It visited two nights in a row, but the third night, when I had set up my camera on a tripod hoping for a better photo, it didn't show up!”

Great Horned Owl by Anjali Mallya

Learn more about owls

Our resource section below has links to more information about owls and how you can help them. Enjoy learning more about these fascinating birds.

And who knows…maybe an owl will call outside your window tonight!

Taxonomy note:  Some of you may know the American Barn Owl as simply the “Barn Owl.” Previously, the bird was classified as part of the worldwide Tyto alba or Barn Owl species of the barn owl family. However, scientific research has shown that the former Barn Owl is actually three different species, distributed in different parts of the world.

Our local barn owl - the most widespread barn owl in the Americas - is its own species, Tyto furcata. It will now be known as the “American Barn Owl.” In the coming weeks and months, you will see records and field guides changed to reflect this fact.


REFERENCES

All About Birds website, www.allaboutbirds.org. Cornell Lab of Ornithology, Ithaca, NY.

Birds of the World. Edited by S. M. Billerman, B. K. Keeney, P. G. Rodewald, and T. S. Schulenberg. Cornell Laboratory of Ornithology, Ithaca, NY. birdsoftheworld.org/bow/home

Breeding Bird Atlas of Santa Clara County, California by William G. Bousman. Santa Clara Valley Audubon Society, Cupertino, CA. 2007.

A Checklist of Birds of Santa Clara County. Santa Clara Valley Audubon Society, Cupertino, CA. Version 3.1: June 8, 2024.

eBird: An online database of bird distribution and abundance [web application]. eBird, Cornell Lab of Ornithology, Ithaca, NY. www.ebird.org

Henion, Leigh Ann. Night Magic: Adventures Among Glowworms, Moon Gardens, and Other Marvels of the Dark. Algonquin Books of Chapel Hill: 2024.

McGowan, Kevin. The Wonderful World of Owls online course. Bird Academy, Cornell Lab of Ornithology, Ithaca, NY. academy.allaboutbirds.org

Wikipedia contributors. "Facial disc." Wikipedia, The Free Encyclopedia, 31 August 2024. Accessed 1 November 2024.

Wikipedia contributors. "Great horned owl." Wikipedia, The Free Encyclopedia, 27 September 2024. Accessed 29 October 2024.

CREDITS

Banner Photo: Great Horned Owl by Teresa Cheng

Questions or comments? Send a note to Julie Amato, the author, at backyardbirds@scvas.org.