The northern hawk owl (Surnia ulula) is a medium-sized owl that lives in the northern forests of North America, Europe, and Asia. It can be found in Alaska, Canada, parts of the northern United States, and across Eurasia. The northern hawk owl has some unique features compared to other owls, including its long tail, hawk-like flight patterns, and tendency to be active during the day. This has led many observers to wonder – is the northern hawk owl nocturnal like most owls, or does it exhibit more diurnal (daytime) activity? Let’s take a closer look at the northern hawk owl’s habits and behavior to find out.
Nocturnal Hunting and Foraging
Despite some of its unusual traits, the northern hawk owl does exhibit primarily nocturnal activity patterns when it comes to hunting and foraging. Several key pieces of evidence support the northern hawk owl’s nocturnality:
- Like most owl species, the northern hawk owl has exceptional low-light vision and superb hearing adapted for finding prey at night.
- Studies using radio telemetry to track northern hawk owls show they are most active in the first few hours after sunset and before sunrise, consistent with nocturnal patterns.
- Prey surveys indicate the northern hawk owl feeds primarily on small mammals like voles, mice, and lemmings. These prey species are generally more active and available at night.
- Examination of northern hawk owl stomach contents and pellets shows they consume mostly nocturnal rodents.
Overall, the northern hawk owl’s peak activity times, sensory capabilities, and feeding habits provide strong evidence that it does most of its hunting under cover of darkness like a typical owl. This nocturnal strategy likely helps the northern hawk owl take advantage of the high activity of its small mammal prey at night.
Some Diurnal Activity
While primarily nocturnal, the northern hawk owl does exhibit more daytime activity than most other owl species. Some key signs of diurnal behavior include:
- Northern hawk owls are regularly observed hunting and flying during daylight hours, especially in the early morning and evening.
- Their keen eyesight and hawk-like flight allow them to effectively hunt in daylight.
- They have been documented attacking and consuming larger diurnal bird species like grouse, jays, and woodpeckers.
- Northern hawk owls will opportunistically hunt animals active during the day, like red squirrels and hares.
The northern hawk owl’s diurnal habits are likely related to the extreme northern latitudes where it lives. During summer months with almost 24 hours of daylight, strictly nocturnal activity may not be as adaptive. The northern hawk owl has evolved to take advantage of diurnal food sources when available. However, it still relies heavily on nocturnal hunting of small mammals that make up the majority of its diet.
Adaptations for Nocturnal and Diurnal Hunting
The northern hawk owl possesses some key adaptations that facilitate its ability to hunt both day and night:
- Excellent eyesight – Northern hawk owls have large, forward-facing eyes with powerful retinal concentration that give them excellent visual acuity in low-light and daylight conditions.
- Acute hearing – They have asymmetrical ear openings and feathers adapted to channel sound waves with precision, allowing them to pinpoint prey in full darkness.
- Stealth flight – With soft, muffled feathers and flexible wings that allow silent flight, northern hawk owls can ambush prey day or night.
- Sharp talons – Large, hooked claws provide a deadly grip on prey of all sizes.
- Camouflage – Plumage colored and marked to blend into trees aids daytime hunting.
The northern hawk owl is well-equipped through evolution to hunt effectively anytime of day while favoring a primarily nocturnal strategy.
Breeding and Nesting
The breeding season offers some additional insights into the northern hawk owl’s daily rhythms. Some key points:
- Northern hawk owls nest in tree cavities, stumps, or old nests of other birds. Nesting starts in early spring.
- While incubating eggs, the female stays on the nest constantly and is fed by the male at night.
- Once eggs hatch, the female broods the owlets primarily at night while the male hunts.
- Both parents hunt to feed the demanding owlets, mainly at night but with some daytime hunting.
- By late summer, owlets fledge and become independent, and nocturnal activity increases for the entire family.
The breeding season requires more continuous daytime nest attendance. But nighttime remains the peak period for hunting to feed both incubating females and growing owlets.
Migration and Territorial Behavior
The northern hawk owl’s migration patterns and territoriality also relate to its nocturnality:
- It is somewhat nomadic in winter, wandering south irregularly in search of food, but primarily migrates at night like other owls.
- While defending nesting territories, northern hawk owls are most vocal and aggressive around dawn and dusk, consistent with their crepuscular (twilight) activity peaks.
- Territorial disputes and boundary reinforcements happen more often during low light conditions.
So while the northern hawk owl exhibits some unusually diurnal habits, key behaviors around migration and breeding territories align with its fundamentally nocturnal nature.
Nocturnality Variations by Season, Location, and Individual
While generally nocturnal, the balance of nighttime vs daytime activity can vary in northern hawk owls based on certain factors:
- During summer’s midnight sun, far northern populations exhibit more diurnal activity than those farther south.
- Some individuals tend to be more diurnal than others even within the same population.
- Nocturnal activity increases during mating and nesting season.
- Daytime activity peaks when feeding nestlings and fledglings.
- Young owls recently independent of parents hunt more during daylight.
- Food availability may determine whether nocturnal or diurnal hunting is more fruitful.
So while fundamentally nocturnal, the northern hawk owl shows flexible activity patterns influenced by seasonal, geographical, and individual traits.
Conclusion
In summary, while the northern hawk owl exhibits some unusual diurnal habits for an owl, the preponderance of evidence indicates it is overall primarily nocturnal:
- It has the typical visual and auditory adaptations for nocturnal hunting.
- Its peak hunting and foraging occurs in the nighttime hours after sunset and before dawn.
- Nocturnal, small mammals like voles and lemmings make up the bulk of its diet.
- Breeding activities reinforce its basically nocturnal nature.
- It migrates at night like other owls.
- Its flexible activity patterns demonstrate facultative diurnality influenced by seasonal and individual traits.
So while not strictly nocturnal, the northern hawk owl’s primarily nocturnal strategies align it with other owls as a creature of the night. Its unique adaptations allow it to thrive at northern latitudes with extreme seasonal variations in light and take advantage of both nocturnal and diurnal food sources. So the next time you spot a northern hawk owl hunting during daylight hours, remember that it still favors the cloak of darkness!