The nests are usually 28 to 38 inches in diameter. They are sometimes used year after year and can be up to 3 feet tall. Both birds construct the nest using deciduous trees approximately 4 to 21 m above the ground. The nests are constructed of twigs while the lining consists of pine needles and bark. Fresh bark, twigs, and pine needles are deposited into the nest throughout the year to keep the nest clean.
Owls compete with the red-tails for nest sites.
Each species is known to feed on the young of the other in order to take the nest site. One to five eggs are laid around the first week of April. The eggs are incubated for about 30 days. Both parents help to incubate the eggs. Males may bring food to the female while on the nest.