This video from the USA says about itself:
Great Horned Owl Hooting Territorial Evening Call At Sunset
31 December 2012
Great Horned Owl (Bubo virginianus) calling for it’s mate on Dixon Branch of White Rock Creek in Dallas, Texas. This particular owl was hooting a territorial call for another owl that can be faintly heard some distance away beginning after the call around the 1:50 mark. The owls call to each other in a duet before finding each other for night hunting and nest building.
Found from the Arctic to the tropical rainforest, from the desert to suburban backyards, the Great Horned Owl is one of the most widespread and common owls in North America. Capable of killing prey larger than themselves, the Great Horned Owl is one of the larger winged predators in the United States.
Often heard but rarely seen the birds are very difficult to photograph since they are nocturnal. This video was shot using Canon Magic Lantern software which allows for extreme low light photography. It was also filmed at a considerable distance giving the owl plenty of space to act naturally. The bird was a couple hundred feet from the camera. It’s important to keep a code of ethics when around large predators such as this. They need a wide berth to not be stressed.
From Transactions of the Kansas Academy of Science in the USA:
Landscape Differences around Nests of Great Horned Owls and Red-Tailed Hawks
Butler Community College, El Dorado, Kansas
Nesting territories of great-horned owls (Bubo virginianus) and red-tailed hawks (Buteo jamaicensis) frequently overlap, with the owls using nests of other raptors. Records of use over a 22-year period in one locality were used to distinguish nesting sites used exclusively by great horned owls, exclusively by red-tailed hawks, and those used by both.
To determine the occurrence of various landscape characteristics within the proximity of a nest structure, I measured the total area of various land use types, total perimeter length, and the size of patches across six different land use types i.e., agriculture, pasture, residential, tree, pond, and roadside within circular plots around nests used by breeding pairs.
The landscape features surrounding nests of great horned owls differed from those surrounding red-tailed hawk nests in total perimeter length and size of patch. These differences are consistent with the fact that great horned owls hunt from perches primarily at night using sensory modalities different than diurnal hunting red-tailed hawks.