Great horned owls sometimes line their nests with feathers and fur from prey birds and rabbits.
From an examination of their nests, it is evident that great horned owls clear out a certain amount of debris before the eggs are laid, and usually line it with a more or less complete layer of consisting of shreds of bark, leaves, or down plucked from the breast feathers of the incubating bird. Feathers from their prey may be added at times.
Near Indian Head, Saskatchewan, the birds occasionally build rabbit fur into their nests before the eggs are laid.
The extent of the lining of downy feathers varies considerably with individual birds from a few feathers to a fluffy mass which practically encloses the large eggs. On the bare floor of a hollow tree or cavity in a cliff the eggs are often enclosed merely by a rim of sticks, stones, or bits of rubbish.
A nest of Bubo virginianus pallescem in Mexico was described as composed entirely of regurgitated pellets.