Species Profile: Great Horned Owl

The Great Horned Owl (Bubo virginianus) is the most widespread species of owl in the Western Hemisphere and North Carolina is no exception. Found from the barrier islands of the Outer Banks to the urban cores of our Piedmont cities and all the way to the towering western peaks, the Great Horned Owl is an adaptable nocturnal killer likely already lurking in your neighborhood. Armed with huge muscular talons, Great Horned Owls are probably the most indiscriminate avian predators in North Carolina. Skunks, rodents, rabbits, and other small mammals comprise the majority of their diet, although Great Horneds also eat other owls, raptors, and birds as large as geese and herons. Snakes, frogs, crawdads, fish, and even insects also fall on the menu. Not picky in terms of their diet, Great Horned Owls are equally cosmopolitan in their choice of habitat and are right at home in human-altered landscapes such as suburbs, farmland, and even city parks.

Identification:
More often heard than seen due to their habit of roosting in dense vegetation during the daytime, Great Horned Owls are colloquially known as “Hoot Owls” due to their deep, successive “hoot” calls. Their typical hooting is deeper and more even-toned than the calls of our other common owls such as Barred and Eastern Screech. Great Horned Owls, especially begging young on or near the nest, also make a variety of shrieks and screams, some of which sound similar to vocalizations of the rarer Barn Owl. If you are lucky enough to see a Great Horned Owl, they can often be identified quickly by their sheer size and bulkiness. Great Horneds are the largest regularly occurring owl in North Carolina, weighing up to 5.5 pounds, with a length up to 2 feet and boasting a wingspan of 5 feet. Females are substantially larger than the males. Look for a white collar patch under the neck, rusty facial disk, fine dark barring on the breast and underparts and an overall mottled brown coloration. When alert, the Great Horned’s piercing yellow eyes and namesake tufts on the head are also good identification clues.

 
Breeding Biology:
Great Horned Owls are among the earliest nesting birds in North Carolina. Hooting activity begins in October, often initiated by the female, and continues through late December or early January, by which time eggs are laid and incubation begins. Owls in North Carolina do not build their own stick nests, and Great Horneds are no exception. Instead, they often commandeer abandoned nests made by crows, hawks, eagles or squirrels. Osprey platforms and buoys are some other unconventional nesting areas that have hosted coastal Great Horned Owl pairs in recent years. Two to three eggs are laid in the midwinter and the female incubates them for approximately a month. The chicks are altricial and helpless for the first several days of life, but they rapidly gain weight with both parents provisioning food. Six weeks after hatching, young Great Horneds begin to “branch out” and leave the nest, but are still incapable of flight. Three weeks later, they fledge and permanently depart the nest though they remain under the care of their parents throughout the summer and into autumn, after which they disperse and define their own territories.

Finding and Coding:
Great Horned Owls are found most frequently in fragmented patches of fields, woodlots, and suburbs rather than unbroken forests. During the daytime, they tend to roost in sheltered areas such as dense evergreen stands. A flock of crows mobbing the top of a pine tree may be a good indication they have discovered a roosting Great Horned Owl. Watch for a few minutes as oftentimes the crows succeed in urging the owl along to a new roost site. Your best bet for finding Great Horned Owls for the North Carolina Bird Atlas is going out pre-dawn or right after dusk during the courtship season when pairs of Great Horned Owls can be heard duetting their low, resonant “hoot” calls. In North Carolina, this falls primarily between October and early January. By February, the comings and goings of adults will be at their peak at the nest site as the ravenous chicks demand meals of voles, rabbits, birds, and reptiles. Searching specifically for a Great Horned Owl nest can be challenging; for such a large bird the incubating female camouflages well amongst the tangles of sticks and leaves that often pass for their nests.

When you hear a Great Horned Owl calling, enter the “Singing” Code “S” with your observation in the North Carolina Bird Atlas portal. You can return to the owls’ territory in a week to upgrade the code to “S7+” which indicates probable nesting in the area. Use the appropriate “Confirmed” codes based on the behaviors you observe at the nest site during this period. Guidance for the use of these codes can be found in the volunteer handbook or at our Understanding Breeding Codes page, and many are self-explanatory such as “ON” (Occupied Nest) and “FY” (Feeding Young). Just after fledging in the spring months, observations of the young, which remain dependent on the adults, can be coded as “FL” (Recently Fledged Young). Listen for their screeching begging calls throughout the night during spring and even early summer.

With increased monitoring during the upcoming winter atlasing period, it is likely that NCBA volunteers will document even more Great Horned Owl nests throughout the state!

— Matt Janson is a skilled NC Bird Atlas technician working in Eastern North Carolina.

Sources:

• Artuso, C., C. S. Houston, D. G. Smith, and C. Rohner (2020). Great Horned Owl (Bubo virginianus), version 1.0. In Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.grhowl.01
• Irvin, Wayne. North Carolina Wildlife Resources Commission Species Profile-Great Horned Owl. https://www.ncwildlife.org/Portals/0/Learning/documents/Profiles/greathornedowl.pdf
• Weidensaul, Scott (2015). Peterson Reference Guide to Owls of North America and the Caribbean. Houghton Mifflin Harcourt.