Reader Todd Mackinaw recently admired how the great horned owl can thrive from the Brooks Range in Alaska all the way to Uruguay in South America.
The knee-high owl known for its “plumicorns” — tufts above its ears that resemble horns — haunts every forested bit of Alaska.
Right about now, in early April, many female great horned owls are sitting on nests they have borrowed from other large birds (no owls build their own nest). Or they are warming eggs atop witches’ brooms — dense tangles of spruce branches caused by a fungus.
One reason great horned owls may range so far is that they will eat anything they can grab. A few years ago, a teenage neighbor of ours shoved a great horned owl off his 7-pound dog in the driveway. The dog recovered with just a puncture wound to its neck.
Madison McConnell, as a University of Alaska Fairbanks graduate student, conducted one of the few studies of great horned owls in Alaska on the northern edge of their range near Wiseman. She wrote in her 2019 master’s thesis that the reproductive success of great horned owls was directly proportional to the amount of snowshoe hares in their diets. She also detected 17 other types of prey, including dragonflies, beetles, small fish and frogs.
Biologists have listed more than 500 prey species of great horned owls throughout North and South America. These include the most common meals — voles and mice — as well as ducks, Brazilian free-tailed bats and striped skunks that perfume the feathers of one of the few birds that will mess with them.
A great horned owl’s talons have more crushing power than the strongest human hand. Its eyes are just slightly smaller than yours. Great horned owls in Alaska and Yukon are larger than most; those living in California and Texas seem to be smallest in the U.S.
Like other owls, great horneds cough up felty pills that contain the bones, fur and other parts of their meals. Scientists and schoolkids pick those pellets apart to see what owls have eaten.
A lack of pellets beneath owl nests puzzled McConnell while she did her field work in the Brooks Range.
That inspired her to attach a trail camera to the trunk of a tree beneath a great horned owl nest to see what was going on. When she later looked at motion-triggered photos, McConnell saw that snowshoe hares were eating the owl pellets.
Hares might have been supplementing their winter diets with the nutrition from bone, feather, fur and carbohydrate residues.
“Owl pellets may be a significant nutritional supplement for hares and squirrels in the boreal forest,” McConnell wrote. Biologists have also documented hares eating soil at mineral licks in the Wiseman area.
But risk accompanies that reward. A series of McConnell’s photos from a trail camera showed an owl flying to the ground right beneath its nest. The owl soon returned with a hare’s severed head in its bill.
Since the late 1970s, the University of Alaska Fairbanks’ Geophysical Institute has provided this column free in cooperation with the UAF research community. Ned Rozell is a science writer for the Geophysical Institute.
