The Short-eared Owl, Another Winter Visitor

Photo: Short-eared Owl, Duke Coonrad/Audubon Photography Awards

Short-eared Owls, Diana Whiting/Audubon Photography Awards

Some observant DC-area birders were fortunate to catch sight of Short-eared Owl in the DC-northern Virginia urban core late in December and early in January. Sightings were reported from Reagan National Airport, the Washington Sailing Marina, Gravelly Point Park, East Potomac Park, and Hains Point, but it’s a relatively uncommon visitor. In northern Virginia, it’s a winter visitor, but it’s a little more likely you’ll see one in the more rural areas of northern Virginia, such Loudoun and Fauquier Counties, primarily because it’s an open-country hunter, foraging in fields and grasslands. 

Like another occasional winter visitor, the Snowy Owl, the Short-eared Owl is a diurnal hunter and so is often visible during the daytime. The birds fly low over grasslands, especially at dawn and dusk. You often see them where you also see Northern Harriers, and they sometimes get in conflict over prey with the harriers and each other. They hunt small mammals and birds.

Short-eared Owl, Terri Shaddick/Audubon Photography Awards

They have short ear tufts, distinguishing them from Long-eared Owls, but the tufts are rarely visible. To identify them, look instead for a medium-sized owl, pale below with dense, vertical streaks on the breast. Its back is mottled brown and buff, and it has black-rimmed yellow eyes and a pale facial disk. 

Short-eared Owls nest on the ground and you may see them flying up from the ground, but in winter they also may roost in trees. Because they are ground-breeders and migratory, they are particularly sensitive to habitat fragmentation and loss. They require relatively large grassland tracts for foraging. Conversion of open habitat to development is a driver in northern Virginia, reducing roosting and foraging areas for these winter visitors.

When we can, let’s all support conservation of important grassland habitat in northern Virginia and around North America to help this captivating predator.

If You Build It, They Will Come, Maybe

Photo: Eastern Screech Owl, Jen St. Louis/Audubon Photography Awards

Evelyn Novins

Owls have fascinated people in many cultures and over time. They appear in folklore representing wisdom to witchcraft. Variously despised and admired, people write about them often. The owl recently has even become a messenger to wizards! They fascinate because they are elusive, and their appearance is eye-catching and a bit eerie. The rounded body, enlarged eyes, and the 270-degree rotating head, coupled with nocturnal behavior and silent flight, make them mysterious creatures.

Eastern Screech Owl, Randy Streufert

I am captivated by Eastern Screech Owls. They have the qualities noted above, and they come in two colors – gray and red. They are robin-sized with cute ear tufts. But most important for me, they love nest boxes, suburban areas, and mixed woods, so that creating an environment for them is doable. If you build it, they will come!

The first step is the nest box. I purchased one from Owl Reach out of Texas – a place with many screech owls and screech owl studies. I followed the directions, but squatters entered the nest before the end of the season. In addition, I found a few things that may have deterred screech owls from moving in. More research gave me the parameters that I needed to try again.

In researching box design, I found several resources: Margaret Barker’s Audubon Birdhouse Book and Carol Henderson’s Woodworking for Wildlife: Homes for Birds and Animals. I decided to modify the Texas design and move toward a more universal one, following guidelines from National Audubon Society. That done, I made and followed this checklist of essentials:

Location - The box should be solidly anchored to a tree 10 to 30 feet above the ground, facing away from the prevailing winds and preferably toward the south, to keep them warm. The box should have an open flight path to its entrance. Although the box can be set up at any time, screech owls begin looking for a home early in the season, so up by January gives you an edge.

Perching Spot - A perching spot is necessary near the box and in near-by trees. Owls like to perch to rest, preen, save energy and watch for prey.

Large Bird Bath - Owls do not need much water, getting much of what they need from their prey; however, they do enjoy a bath. It’s suggested to have one made with a sloping edge so they can ease in.

Brush Pile - A brush pile nearby to help supply food is a must. The pile can include sticks, grass trimmings, root balls, and fallen branches. Small rodents and insects inhabit these piles providing abundant food for the owls. The screech owl eats many large insects such beetles and crickets and a variety of small mammals such as shrews, voles, moles and sometimes bats. In addition, lizards, frogs, earthworms, and crayfish are part of their natural diet.

Things To Avoid – Remove netting of any sort (such as a soccer goal or basketball hoop) from the nest-box area to prevent entanglement. Turn off or dim heavy outdoor lighting, particularly seasonal lighting. Do not use recorded screech owl calls to attract the birds. It creates stress on the listening owls and may attract predators, thus discouraging the owl you want to invite and alarming other birds unnecessarily.

Once you have attracted owls, there are some additional rules to follow:

• Avoid helping them eat by putting out food or releasing caged mice – they will not survive. The owl must hunt live prey - so do not offer dead rodents.

• Longer lawns provide an environment for small rodents, an essential food source - so mow less. Moles, mice, shrews, and voles thrive in longer grass providing a smorgasbord for the owl.

• It’s critical to avoid rat poisons and pesticides. If owls eat poisoned prey they can suffer neurological damage leading to debilitation. This secondary poisoning or secondary toxicity is a problem for all wildlife.

I have satisfied all the items on my checklist, but no luck this year so far. Plus, it’s late to hope to attract a screech owl this year. I have not heard the signature whinny or other distinctive calls of the screech owl, but I am not giving up hope.

If you are interested in your own backyard project, here are a few links for materials that may help:

• Melissa Mayntz, How to Attract Owls to Your Yard

• Kevin Walsh, You Can Attract Screech-Owls to Your Yard

• Garth C. Clifford, 12 Tips on How to Attract Owls to Your Backyard

• Audubon Guide to North American Birds, Eastern Screech Owl

Autumn Acoustics and Great Horned Owls

Photo: Great Horned Owl, Michael Rosenbaum/Audubon Photography Awards

Deidre Bryant

Autumn is in full swing. November and December are the best times to enjoy the beautiful sound of hooting, especially from Great Horned Owls (Bubo virginianus). Although they call a variety of wilder environments home, they can live among us on farms and in small woodlots and city and suburban parks. We can hear them most effectively now because the end of our calendar year is courting and territory setting time for Great Horned Owls, and late fall weather creates conditions that allow us to hear the birds’ calls better.

Great Horned Owl, Michael Rosenbaum/Audubon Photography Awards

The Great Horned Owl is probably one of the most recognizable birds in the Americas, with its large fluffy feathers, pointed tufts on its head, and unmistakable low, but soft call. A common hooting pattern is a longer “hooooooot,” followed by three or four shorter hoots. During a duet, females will reply to a male with a raspy hoot in a higher pitch. Great Horned Owls have a range of other vocalizations, too, some of which sound like a screeching cat. Despite their notable appearance and recognizable calls, they are not always easy to locate because of their nocturnal habits and preference for places with little to no light pollution. 

Nevertheless, at the right location, and especially at this time of the year, you can hear a chorus of hoots piercing the night and providing an enchanting soundtrack from dusk till dawn. That’s because in November, male Great Horned Owls begin scouting and claiming vast territories (an average of about 1.5 square miles) around their nests. Come January, mating will already be underway and a pair will begin settling in their home. They do not build nests, instead typically taking over nests previously used by squirrels, red-tailed hawks, or other arboreal animals. 

When I was much younger, I used to think owls only called during the cooler months and at night. Owls will actually hoot throughout the year and quite often, even when the sun is up. But, in many ways, it’s much easier to hear them on crisp, cold nights. If you’ve ever been to a night football game and listened to a marching band during halftime or when they’re in the stands, you’ll know exactly what I’m talking about. Sound doesn’t get louder as the air gets colder, but it travels farther.

Sound is carried by the collision of vibrating molecules in a longitudinal wave, and sound waves travel faster in warm air because warm air molecules are more energetic than cold air molecules. Faster moving molecules mean sound waves will, in fact, travel faster. Relative humidity also affects sound. Because increasing humidity lowers the density of air and its ability to absorb sound, sound waves move faster in high humidity than in low humidity. On the other hand, fall and winter conditions carry sound farther, even though it may travel more slowly. A number of fall conditions can cause this effect.

1. Temperature inversion. Sound moves in all directions from its source, including up. During cooler months, a layer of cold air sits under a layer of warm air, and the boundary between them refracts or bends the sound waves, redirecting them toward the ground. (Think of how a prism affects light.) When the sound waves oscillate, or move back and forth, between the cold and warm air layers, they are amplified and can be heard over a greater distance.

2. Leaf fall. The absence of leaves from deciduous trees and shrubs prevents sound from being dampened, allowing sound to travel farther.

3. Windy conditions. The wind on breezy days and nights also can refract or bend sound waves. Wind moves faster at greater heights because it encounters fewer obstacles. The difference in speed of the wind causes sound waves to bend towards the ground and travel farther when they travel with the wind (but upwards if they’re travelling against the wind). When an owl is hooting on a windy day, its hoots travel farther downwind than on a still day.

The fall acoustics help owls claim and hold nesting territory. The distance sound travels in some fall conditions allows hooting to be more effective in alerting intruders who enter a claimed territory or in signaling the presence of a threat to other owls. Better acoustics also facilitate courtship displays over long distances. 

Of course, even without the assistance of fall conditions, territorial hooting, because it is generally very low-pitched, can travel farther without significant reduction. So why does low-pitched or deep sound travel farther? Pitch refers to frequency, and low frequency sound is from a sound wave that oscillates fewer times per second. Low frequency waves travel farther than high frequency waves because there is less energy from oscillation transferred to the medium (in this case, it’s air) allowing them to have relatively more energy left over to travel longer distances. Think of a fog horn, which produces a low-pitched sound.

If you’re interested in more than territorial hooting, here’s a link to an interesting article on the variety of owl vocalizations.

As with many birds, great acoustics are paramount in acquiring a mate and claiming territory. However, it’s quite fascinating how Great Horned Owls are able to take advantage of their cold, dark environment while other birds, who breed in the spring and summer, have migrated elsewhere. And, anthropomorphizing just a little, isn’t their calling out to a long-term (maybe life) mate over the miles just a little romantic? 

Happy hooting season!

Barred Owl Fledgling Leaves its Nest

Photo: Barred Owl fledglings, Dorli Bokel

Lisa Mackem

Barred Owlet, Dorli Bokel

Reston resident Dorli Bokel doesn’t consider herself a birder, but she loves the Barred Owls that she often hears nearby – especially the young ones. “I love watching them turn their heads – almost like it’s on a rotation axel. The fuzzy babies are adorable.” Recently, she saw one of the owlets fledge, right on her deck railing. “I just looked outside, and the owlet was just sitting there. It started turning around, trying to get its footing…timidly walked for a bit, turned, and walked more. We were mesmerized.” Dorli estimates that the owlet spent five hours on her deck, then returned two days later. She took this video on the first day and additional pictures on the following days.

Unlike most young birds, Barred Owl chicks fledge before they can fly. They leave their nest when they are 4-8 weeks old but don’t master flight until they are up to 12 weeks old. Dorli doesn’t know how the owlet in her video got to her deck railing, where she says there is nothing to climb on, and the trees surrounding it are very high. However, Barred owlets are known to climb out of their nest using their beaks or talons to sit on branches, and hop to nearby limbs or other surfaces, climbing up to 15 feet.

Dorli noticed early this spring that the owls hooted during the day. Now she only hears them at night. This pattern matches the Barred Owl mating season, with courtship activities beginning in February and breeding between March – August. 

Barred Owls mate for life, and usually have a single clutch of 2-3 white eggs each year. The incubation period lasts 28-33 days. After they hatch, young Barred Owls can stay near the nest for up to 6 months, rarely straying from each other and often sitting side by side. Adults care for their young for up to four months – much longer than many owl species. Most Barred Owls remain close to their birthplace and their nest sites can be maintained for years.

Northern Virginia residents hear Barred Owls often, and sightings are not uncommon. Dorli hopes that someone else will share her unique experience of watching an owlet fledge. 

More than a century ago, Harriet Tubman used her knowledge of the natural world, including the call of the Barred Owl, in her efforts to guide people to freedom. Read the full story from Audubon.

Barred Owls in Reston

Photo: Barred Owls, Lisa Mackem

By Lisa Mackem

Barred Owls are some of our most intriguing local birds. Most people will recognize their hoot-sequence call that sounds like, “Who cooks for you, who cooks for you all?”  Unlike many other owls, they are semi-nocturnal. Their name comes from their striped plumage, or “bars.” They are the only eastern owls with deep brown eyes, which can appear blue-black in certain light. Females are larger than males, and only females incubate chicks, or owlets.

I often see Barred Owls near my home – usually when they are quietly perched in trees, and once when one was sitting on the ground. Barred Owls have distinct personalities. They watch people  intently, but with different levels of tolerance. When I take pictures of them, some of these owls change positions as if striking various poses. They aren’t disturbed when I stand near or directly under their perch. Others hoot with apparent annoyance or anger and fly to a more distant perch.  

The varied behavior described above might be related to the presence of other birds in the area. Small songbirds recognize Barred Owls as a threat, and sometimes band together to harass or “mob” them. Crows especially have a long-standing animosity towards owls. They frequently mob Barred Owls, chasing them from perches and potential prey. The owls will sometimes attack and eat individual crows, or other small birds (although birds are not their preferred prey), but they will retreat from a mob. 

As Leigh Clavez wrote in The Hidden Lives of Owls, Barred Owls are the opportunists of the owl world, easily adapting to varied habitats, including mixed forests and disturbed areas. Although they prefer tree cavities, they will also use the nests of Red-shouldered Hawks, crows or ravens. They eat a variety of small mammals and birds, amphibians, reptiles and invertebrates but they cannot catch cats and dogs. 

Great Horned Owls are the Barred Owls’ only natural enemy, but these owls are not seen frequently in Reston. Sadly, Barred Owls are often hit by cars when they swoop down to capture prey along a road. If the prey has been attracted by food people discarded out of a car window, the encounter can become deadly for the owl. I have seen some of these owl casualties along Lawyers Road in Reston. 

Barred Owl courtship begins in February and breeding is from March – August. They will lay 2-4 eggs, and the incubation period is 28-33 days. Owlets fledge at 35-40 days, but adults care for their young for at least 4 months – much longer than other owls. Young owls call for their parents with a distinctive screeching hiss. They have a fuzzy appearance until they are fully mature. Barred Owls often use the same nest sites, and can occupy territories for 2-3 decades, suggesting strong site fidelity over time. They do not migrate. Captive Barred Owls can live to their early 20’s, and wild owls live for 10-20 years. They mate for life, but if a mate dies, the survivor will likely mate again. 

Watch here to follow a pair of Barred Owls through their nesting.  

Twelve Things You Should Know About Owls

Photo: Barn Owl, Stacy Howell/Audubon Photography Awards

Roger DiSilvestro

Burrowing Owls, Ann Kramer/Audubon Photography Awards

Owls are our nocturnal neighbors, leading secretive lives in woods and fields around us. Rarely seen during the day, they can be hard to spot at night. Here are 12 things to know about these elusive birds:

1. The fossil record indicates that owls originated more than 60 million years ago, probably about the time dinosaurs went extinct.

2. The world is home to 220 to 225 living owl species, depending on which taxonomist you ask.

3. Most owls feed on small birds and mammals, though some are specialists at preying on fish.

4. A nesting pair of Barn Owls may consume some 3,000 rodents while raising their young.

5. Males catch food for themselves, their offspring, and their mates, which stay on nests while incubating eggs and caring for young; if food is scarce, however, the male eats first.

6. Most owls are active at night (nocturnal) but some are active by day (diurnal). One diurnal owl is the Burrowing Owl, often associated with prairie dog towns in the West, where they can be seen bowing politely to one another on the mounds surrounding prairie dog holes.

7. Night-hunting owls are the stealth bombers of the bird world, equipped with large eyes specially adapted to seeing in darkness, and with ears structured to pick up the slightest sound, giving them advantages over their less acutely equipped prey.

8. The feathered disks around the eyes of owls help to funnel sound to the ears, and owls can move the feathers to accentuate sounds.

9. The eyes of owls are placed side by side in the skull, giving the birds excellent depth perception highly useful for zeroing in on prey.

10. Adaptations in the neck bones allow owls to turn their heads 270 degrees, giving them a wide field of view.

11. Owl flight feathers have fringe-like or serrated edges that muffle the sound of flying owls, allowing them to sneak up on prey.

12. Owls regurgitate indigestible parts of their prey, such as bones and teeth, in pellets that biologists can use to study owl eating habits.

Bonus Fact

The world’s smallest owl is the Elf Owl, about 5 inches long and weighing 1 ounce. Two species are rivals for largest species: the Eurasian Eagle-Owl and Blakiston’s Fish Owl, both of which can measure up to 28 inches long and weigh in excess of 9 pounds; however, the great gray owl is longer, at up to 33 inches, so some birders contend that it is the largest owl species, though it is roughly half the weight of the other two.

Great Gray Owl, Ken Shults/Audubon Photography Awards

Bird of the Month: The “Sparred” Owl

By Elise Brosnan

The Spotted Owl just can’t get a break. Endemic to old-growth forests in the Pacific North west, the endangered owl’s population was already declining due to deforestation, but now they have been forced to accommodate an inconsiderate guest: Barred Owls. Native to the eastern half of North America, the Barred Owl’s territory has been expanding westward since the turn of the last century. By the 1990s, Barred Owls have become a permanent fixture throughout much of the Spotted Owl’s historic range. Larger, more aggressive, and more opportunistic than Spotted Owls, Barred Owls have been identified as a significant new factor driving the Spotted Owl’s population collapse.

However, Spotted Owls hold no apparent ill will towards Barred Owls. The two species occasionally hybridize, or mate, producing an offspring that is half spotted and half barred. As you might expect, “Sparred Owls” look like both of their parents. They have the Barred Owl’s larger size, but the Spotted Owl’s darker coloring. Their breast plumage is a mixture of spots and bars, described as looking like a checkerboard pattern. Their call also reflects their mixed heritage; a series of staccato Spotted Owl-like “hoos” followed by a Barred Owl-like “hoo-ah,” described by a biologist as “sort of like a Spotted Owl being strangled.”

Morgan, a Sparred Owl, is help in captivity at Chintimini Wildlife Center in Corvallis, Oregon. Photo courtesy of Chintimini Wildlife Center

Hybridization is surprisingly common in birds. Up to ten percent of birds are suspected to hybridize with other species, at least occasionally. However, hybridization may be increasing as the historic range of many bird species changes. As we lose grassland in the Great Plains states, eastern forest birds are interacting with western forest birds in a way that has never been seen before. Because of climate change, both western and eastern species are finding northern territories more hospitable. The Barred Owl made its way west by colonizing Canadian forests at the very north of its range, before looping south into Spotted Owl territory.

Great Plains hybridization has threatened species before. The Midwestern Blue-winged Warbler is expanding its range eastward, where it outcompetes and hybridizes with the Golden-winged Warbler.  (However, some biologists argue that Golden-winged and Blue-winged Warblers are two variants of the same species, and, by definition, cannot be under threat from itself.)

Therefore, what should be done about Barred Owls? Experimental cullings have occurred, with moderate success. However, some environmentalists argue that the arrival of the Barred Owl has provided a convenient scapegoat for another enemy of Spotted Owls: the logging industry. “Competition from Barred Owls may well need to be addressed on an interim basis until Spotted Owls’ populations can be returned to health,” says Bob Sallinger, conservation director of the Audubon Society of Portland, Oregon, “but unless critical habitat needs are adequately addressed, Barred Owl control will be nothing more than a sad and pathetic footnote on the road to Spotted Owl extinction.”

Sources:

Axelson, G. (2016) Golden-winged and Blue-winged Warblers Are 99.97 Alike Genetically. Living Bird Magazine. Cornell Lab of Ornithology, Ithaca, NY, USA. Retrieved from https://www.allaboutbirds.org/mixed-wing-warblers-golden-wings-and-blue-wings-are-99-97-percent-alike-genetically/