The northern hawk-owl generally starts its mating rituals at the beginning of March.
After calling and pairing is complete the northern hawk-owl will build a nest and start to lay eggs.
On average the northern hawk-owl will lay 3–11 eggs per brood.
The nest sites are usually the tops of hollow stumps of old dead spruce trees.
These nesting sites are usually 2–10 m (6.6–32.8 ft) above ground for the North American S. u. caparoch and approximately 4–5 m (13–16 ft) above ground for the Eurasian S. u. ulala.
The specific dates of egg appearance can be quite variable depending on locality.
In central Canada eggs are usually laid from March 30 to the 5th of June.
On Newfoundland the appearance of eggs occurs later, between May 9 and June 11.
In Finland however, eggs can be found anywhere between the 30th of March to the 23rd of June.

For the most part the female northern hawk-owl does the incubating of the eggs whilst the male forages for food.
Once the chicks have hatched their roles shift drastically.
At about two weeks into the chicks' lives the female starts to leave the nest for long spans of time (5 hours or more).
This span of time is presumably when the female hunts.
The male however, will guard the nest diligently until the chicks leave.
When predators (usually other raptors) fly nearby, the male will sometimes chase them away from the nest if he feels it is necessary.
Once the owlets have grown to a size which allows less parental supervision, they will leave the nest.
This occurs on average after their 21st day, and can begin as early as mid-June.
After this the female will provide most of the care.
However, the male will remain close and will still feed his young on occasion.

The northern hawk-owl has also been known to nest on cliffsides.
It has little fear of humans, and will attack if the young are approached too closely.
The northern hawk-owl generally starts its mating rituals at the beginning of March. After calling and pairing is complete the northern hawk-owl will build a nest and start to lay eggs. On average the northern hawk-owl will lay 3–11 eggs per brood. The nest sites are usually the tops of hollow stumps of old dead spruce trees. These nesting sites are usually 2–10 m (6.6–32.8 ft) above ground for the North American S. u. caparoch and approximately 4–5 m (13–16 ft) above ground for the Eurasian S. u. ulala. The specific dates of egg appearance can be quite variable depending on locality. In central Canada eggs are usually laid from March 30 to the 5th of June. On Newfoundland the appearance of eggs occurs later, between May 9 and June 11. In Finland however, eggs can be found anywhere between the 30th of March to the 23rd of June.
For the most part the female northern hawk-owl does the incubating of the eggs whilst the male forages for food. Once the chicks have hatched their roles shift drastically. At about two weeks into the chicks' lives the female starts to leave the nest for long spans of time (5 hours or more). This span of time is presumably when the female hunts. The male however, will guard the nest diligently until the chicks leave. When predators (usually other raptors) fly nearby, the male will sometimes chase them away from the nest if he feels it is necessary. Once the owlets have grown to a size which allows less parental supervision, they will leave the nest. This occurs on average after their 21st day, and can begin as early as mid-June. After this the female will provide most of the care. However, the male will remain close and will still feed his young on occasion.
The northern hawk-owl has also been known to nest on cliffsides. It has little fear of humans, and will attack if the young are approached too closely.
Northern hawk-owl