Thursday, April 22, 2021

Screech Owls are Cute Killers

screech owlThere is an amusing scene in the comedy “My Cousin Vinny”, where the Joe Pesci character, an inexperienced lawyer from Brooklyn, where local wildlife tends towards pigeons, rats, crows, and stray cats, is staying in a remote back woods Alabama cabin, preparing for the big murder trial, and is startled by a blood curdling shriek in the dead of night. He explodes out the front door, wildly firing a pistol, as the camera suddenly focuses down on a small screech owl in a tree.

Wendy and Screech Owl

Wendy Hall of the Adirondack Wildlife Refuge with a screech owl. Photo by Steve Hall.

Eastern Screech Owls resemble adorable little plush toys, but are stone killers, often heard, but seldom seen. They occur from grey to brown to rufous color phases, as well as in intermediate phases, all of which can intermate. About a third of all Eastern screech owls are reddish, with the percentage declining as you survey further north and west. Western screech owls are gray. Screech owls weigh four to nine ounces, are seven to ten inches tall, and have a stubby wingspan of 18 to 24 inches. As with other owls, females are larger than males, with females doing most of the incubation and nest defending, and males bringing prey back to the nest.

The screech owl’s stocky but short appearance appears neckless, and features small “ear tufts,” display feathers, which have nothing to do with hearing, but break up the top of the owl’s head, helping camouflage the owl. Large talons attach to feathered tarsi, making the screech owl a powerful little hunter. When flying through woods, they are more like a stubby Jeep than a sports car. If a screech owl worries about being spotted by a predator, such as another owl, or a passing person, it may close its yellow eyes, tightening its feathers, while stretching and twisting its torso to present a narrower silhouette, which may resemble a broken snag or branch, and they may blend in with the tree bark. The only owl smaller in the Adirondacks is the saw whet owl.

It is tough out there in nature. Starvation tends to be the number one killer of wildlife, with bears being the sad exception, dying more often from the rifles of hunters, homeowners, and rangers. Owls are not sentimental, with great horned owls preying on all smaller owls, such as barred owls, as well as crows, hawks and even eagle chicks. Barred owls in turn prey on long eared owls, barn owls, screech owls and even tiny saw whet owls, who may themselves fall victim to screech owls.

screech owl

Photo by Anne Fraser, provided by Adirondack Wildlife Refuge

Screech owls perch on branches as low as ten feet high, observing what moves beneath, and diving at mice, voles, rats, chipmunks, but will also go after small birds like starlings, finches, wax wings, and even bats in flight. Grouse sized birds are occasionally taken. Screech owls will use bird baths for bathing and drinking and will monitor nearby bird feeders for vulnerable songbirds. Blue jays, chickadees and other small birds make a noisy commotion when discovering a roosting screech owl, mobbing, and harassing them, trying to force the screech owl to leave an area, while alerting other songbirds to the potential danger. Hunting primarily from dusk for several hours, as well as around dawn, no small critter is safe, and screech owls will grab large flying insects, as well as snakes, frogs, salamanders, and crayfish.

As with other owls, screech owl hearing is aided by asymmetrical ears, one higher and larger than the other, located behind the eyes, which enables the owl to triangulate the location of prey. Sounds hit one ear, up or down, left or right, a microsecond before hitting the other. The eyes are fixed in the socket and cannot rotate, so when the owl hears a sound, they coordinate the arrival of the sounds by swiveling their heads up to 270 degrees, on their fourteen neck vertebrae, twice the number we have.  When the sounds land simultaneously, by definition, the screech owl is staring at the location the prey pretty much must be.

Screech owls are nocturnal hunters. The eyes are long and tubular and have many more rods, which detect motion and change, than cones, which resolve color. As with other owls, little movement escapes their attention. The flight feathers are fringed, softening the sound of flight, allowing the owls to take their prey by surprise.

Owls lack crops, which other birds use to store food for later consumption. At the same time, they have no teeth, so they cannot chew their food, and they cannot digest bone, feathers, or fur. Prey are usually swallowed whole or brought back to the nest to be dismembered by beak and talon, and then shared.

The owl’s digestive system is composed of two parts: the smaller proventriculus produce enzymes, mucus, and acid, which begin the digestive process, while the next stop, the larger ventriculus or gizzard, separates the indigestible parts, forming a pellet, which is stored in the proventriculus before being regurgitated by the owl hours later. Screech owls produce about two pellets per day, and the owl cannot swallow prey again, until the pellet is ejected. The pellets are in great demand by kids visiting the Wildlife Refuge, who will then dissect them in the classroom to see what the owl has been eating.

Eastern Screech owls range from the Rockies east, preferring overlapping undefended territories of 100 to 200 acres, mainly in older deciduous and mixed forests with many natural cavities like woodpecker holes. hollow branches, tree stumps or even man-made boxes, built to that purpose, or inadvertently having the right dimensions to serve as such. Older coniferous forests work as well, and favored territories border open fields and wetlands, which provide most of their prey. Screech owls are solitary creatures, except during mating and nesting seasons, and do not migrate.

Because of their diminutive size and the difficulty in spotting them, screech owls easily live among people in suburban settings, and even urban settings in parks. Think about it. Most folks hear barred owls, which defend larger territories, calling frequently, and occasionally see them from time to time, but few people have noticed screech owls, even though there are more of them than barred owls in areas where both occur. Screech owls are only found in the new world, with most occurring in the lower 48 states. Estimates put their total population of all 23 recognized species at about 900,000.  Uncovered fossils indicate that screech owls, as they appear today, go back about 2.5 million years, with species diversifying up to 5 million years ago. Threats to screech owl survival include warmer seasonal weather, forest fires, habitat destruction and predation by larger owls, weasels, snakes, and corvids.

Like most owls, screech owls are monogamous, but before occupying the nest, which is often the same one chosen by the female the year before, there will be a sort of stiff courtship, with males and females calling each other as they move closer.

screech owl

Photo by Anne Fraser, provided by Adirondack Wildlife Refuge

As Cousin Vinny discovered, male screech owls may announce their presence within their territory with sharp, piercing calls, as well as a mournful thirty-five note trill, which can resemble a high-pitched horse whinny. When courting, males will call repeatedly from progressively closer branches until male and female are together. The male bobs and swivels his head, dips his entire body, and even slowly winks one eye at the female. If she ignores him, bobbing and swiveling motions intensify. To accept him, she moves closer, and they touch bills and preen each other. Pairs mate for life but will accept a new mate if the previous mate disappears.

Males will maintain multiple nesting sites, averaging ten to twenty feet above ground, within a much smaller ten-to-twenty-acre section of their territory, which they will defend, and during mating season will store food in each of them as an enticement to females to choose a particular nest. Occasionally, this system may result in an exhausted male supporting more than one female’s nest.

Young are raised between March and May. The female will incubate a clutch of two to six eggs for about 27 to 34 days, while the smaller nimbler male will bring her prey. The egg laying is sequential, with the first born often taking advantage of younger, smaller siblings, occasionally pushing one out of the nest, committing siblicide, to garner a greater share of the food the male is bringing to the female. The fast-growing chicks beg for food with a peeping sound for their first few weeks, which becomes a more insistent “keeer-keeer” sound as they near fledgling size.

At about a month, the fledges are branching, climbing out of the nest, perching on branches, exercising their wings in preparation for that first flight. As with other owls, the first attempt at flight may be a bust, with the fledge ending up on the ground, being fed by mom until the fledge is strong enough to fly on its own, or a predator, such as a skunk, comes across it. First year birds grow larger flight feathers than their parents have, to compensate for their relative lack of strong flight muscles. Screech owls live an average of ten years in the wild, twice that in captivity.

Photo at top: A red phase screech owl, taken by Dr. Greg Gulbransen, provided by Adirondack Wildlife Refuge

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Steve Hall

Steve and Wendy Hall run the Adirondack Wildlife Refuge and Rehab Center in Wilmington. They've been rehabbing and releasing wild animals for over 45 years, specialize in predators, keep wolves as the cornerstone of their educational program, and have lived in the Adirondacks for the past 20 years. The Adirondack Wildlife Refuge became a non-profit about 10 years ago.

Visit www.AdirondackWildlife.org to learn more.




2 Responses

  1. Nora says:

    Wow a very interesting and great article, thank you Steve for sharing your knowledge on these fascinating characters, have made many trips to your refuge and rehab center, have always enjoyed when you do your talk on the wolfs , look forward to many more visits!! Thank you both for your love and dedication to all the animals in your care .

  2. Vanessa Banti Vanessa says:

    They really ARE adorable. Never heard one myself, but now that I’m armed with the Cornell app I shall learn the sound for future listening. These articles are great fun!

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