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Great Horned Owl unmatched as predator
By Brandon Caswell, correspondent
Feb. 1, 2019 10:39 am
If you were asked to name an Iowa bird of apex predator status, what might come to mind?
The Great Horned Owl, also known as the tiger owl, is a common raptor that ranges from arctic North America to far southern South America.
Tiger owl is a fitting a name. This owl species can hunt any of the other Iowa owl species. Additional impressive prey items include Ospreys and falcon species, including the Peregrine. Great Horned Owls also take mammals larger than their own size and occasionally attempt for small pets, such as lap dogs.
Having the most diverse dietary breadth of any North American raptor, their staple food in Iowa is probably rabbits, voles and mice. Like other owls, the Great Horned swivels its head to over 180 degrees to accommodate the inability to move the eyes within its sockets.
Nesting takes place outside of the 'traditional” time frame for most birds.
In Iowa, Great Horned Owl will begin to nest as early as January. They often prefer trees such as cottonwood and pine, sometimes using unoccupied nests built by other species. Nesting also may take place in tree cavities or sometimes on human-made structures.
Juveniles, or owlets, are very fluffy in appearance. Like adults, the juvenile has yellow eyes and typically a downy white head that surrounds a darker facial disc.
Adults of both sexes are similar in appearance. Yellow eyes and large ear tufts are standard, but facial and body coloration vary regionally. Iowa gets a nice sampling of color variation, with most having a tawny colored facial disc. Facial discs will transition from light tawny to nearly white in the 'sub-Arctic” races of Great Horned Owl. These lighter owls are typically seen further north and west in the state.
Most adults in Iowa have mottled uppersides, usually consisting of black, gray and tawny colors. Undersides are striped black and white with varying amounts of tawny in the breast and belly.
Look for Great Horned Owl in woods, especially those with scattered open areas. However, habitat preference is quite varied, reflecting its wide range in the Americas. Suburbs, parks, deserts, mountainous regions and tropical, evergreen and deciduous forests all support this stealthy, yet formidable raptor.
PHOTOGRAPHY ADVICE
Acclimating your camera to the elements in the winter is important. It may be a good idea to place your camera and lens in a bag and throw it in your automobile five or 10 minutes before starting the auto to head out. A lens that is not acclimated can fog up immediately after exiting a vehicle. This is the last thing you want happening when the perfect winter shot presents itself.
OTHER BIRDS IN FEBRUARY
l February can be a great month for owls. Great Horned Owl may begin nesting already. Look for Barred Owl in mature forests and along wooded creeks. Look for Eastern Screech Owl in town and in rural areas, as well. They like to sun in south-facing hollow tree cavities. Long-eared owls roost in the day within dense stands of conifers near open areas, such as grasslands. Lastly, look for short-eared owl around dusk in open grasslands. The west end of The Eastern Iowa Airport, along Cherry Valley Road SW, can be a great place to see this species shortly before or after sunset. They tend to materialize out of the sky from the west and will work their way to the open grassy areas of the airport to hunt. They have a very moth-like flight pattern.
l Winter finches will continue at feeders well into February.
l Look for Bald Eagles and waterfowl around low head dams. The dam by Iowa River Power Restaurant in Coralville can be a great place for eagle viewing.
FEBRUARY EVENTS
l Feb. 10, 8 a.m. - Quad Cities & Mississippi River for gulls, waterfowl and other winter birds with leader Chris Caster. We'll stop at locks and dams, riverside parks and other hot spots like Fairmount Cemetery for winter finches. Walking is usually a short-distance from frequent stops. We'll stop for lunch at a nearby restaurant. Return time is late afternoon. Dress for cold and wind, and bring a spotting scope if you have one. Meet at the Hy-Vee parking lot, 1125 N Dodge Street, Iowa City.
l Feb. 10, 1-3 p.m. - Freeze Fest at the Terry Trueblood Recreation Area lodge. The club will have a viewing area with scopes and information about feeders for winter bird-watching.
l Feb. 21, 7 p.m. - Jason Taylor, Property Stewardship Specialist with Bur Oak Land Trust, will present 'Improving Midwestern Bird, Mammal, and Insect Pollinator Habitat through Active Land Management” at the Iowa City Bird Club meeting.
l Feb. 23, 8 a.m. - Macbride Nature Recreation Area. Cure your cabin fever with a hike in the winter woods. Start with feeder birds at the bird blind, then continue on (if desired) to hike surrounding trails. Target species are purple finch, red-breasted nuthatch, pine siskin, brown creeper, woodpeckers and more. Meet leaders Deb and Mark Rolfes at the MNRA main parking area where heated restrooms are available.
l Brandon Caswell has undergraduate degrees in biology, anthropology and geology. His graduate degree centered on dating continental collisions within the Precambrian Canada Shield. Bird-watching and nature photography are among his favorite hobbies. He resides with his wife and son in Marion. Email brandon.caswell83@gmail.com with birding-related questions, including questions about activities.
An adult Great Horned Owl rests in a cottonwood in Lone Tree during the day while its mate was on their nest in a cavity within the same tree. (Brandon Caswell/correspondent)
Great Horned Owl owlets wait for their parents within a tree cavity in Lone Tree in early April. (Brandon Caswell/correspondent)
An owlet rests with an adult Great Horned Owl in a conifer in Dillon, Mont., in May. (Brandon Caswell/correspondent)
A bald eagle soars overhead above the Mississippi River at Lock and Dam 14 in Scott County. (Brandon Caswell/correspondent)
A Gadwall and Mallard spend a very cold winter day in January at the low head dam near Iowa River Power Restaurant in Coralville. (Brandon Caswell/correspondent)