The Barred Owl (Strix varia) is a captivating species of owl found across North American forests. This article delves into the essential aspects of the Barred Owl’s life, providing a comprehensive overview for enthusiasts and those interested in avian conservation. Understanding their habitat needs, dietary habits, nesting behaviors, and general conduct is crucial for appreciating and protecting these magnificent birds. As we explore these facets, we will also touch upon their conservation status and the factors influencing their populations.
Habitat of the Barred Owl
Barred Owls are year-round residents of mature, mixed forests, with a preference for areas near water sources. They thrive in large, unfragmented woodland blocks, which likely offer a greater diversity of prey and suitable nesting cavities. Their preferred habitats encompass a range of environments, from swamps and streamsides to uplands, and can include various tree species such as hemlock, maple, oak, hickory, beech, aspen, white spruce, balsam poplar, Douglas-fir, lodgepole pine, and western larch. The presence of large, old trees is particularly important for providing suitable nesting sites.
Diet and Hunting Strategies
The diet of the Barred Owl is varied, consisting of numerous small animals. This includes squirrels, chipmunks, mice, voles, rabbits, and various birds, amphibians, reptiles, and invertebrates. Their hunting technique involves perching on an elevated spot and scanning their surroundings with keen eyesight and hearing. They are adept hunters, capable of perching over water to snatch fish or even wading in shallow waters to catch fish and crayfish. While they are primarily nocturnal hunters, active shortly after sunset and throughout the night, they may also hunt during the day. Stored prey can be found in their nests, the crooks of branches, or at the top of dead trees. Small prey is typically swallowed whole, while larger prey is consumed in pieces, starting with the head.
Nesting Behavior and Nest Description
Barred Owls typically choose natural cavities in large trees, situated at heights of 20 to 40 feet, as their nesting sites. In the absence of suitable cavities, they may utilize abandoned stick nests built by other animals like hawks, crows, ravens, or squirrels. Human-made nest boxes can also serve as nesting locations. It’s noted that Barred Owls may investigate potential nest sites up to a year before occupation.
These owls are not known for extensive nest construction. They generally do not alter existing tree cavities or abandoned stick nests significantly. However, they might add lichen, fresh green conifer sprigs, or feathers to stick platform nests and may flatten or clear the top of old squirrel nests. The dimensions of these cavities typically range from 10 to 13 inches in width and 14 to 21 inches in depth, with some recorded cavities being much deeper.
Nesting Facts at a Glance
- Clutch Size: 1-5 eggs
- Number of Broods: 1 per year
- Egg Length: 1.7-2.2 inches (4.3-5.6 cm)
- Egg Width: 1.5-1.8 inches (3.8-4.5 cm)
- Incubation Period: 28-33 days
- Nestling Period: 28-35 days
- Egg Description: Pure white, with a rough surface.
- Condition at Hatching: Helpless, covered in white down, with eyes closed.
Barred Owl Behavior
During daylight hours, Barred Owls rest on branches or within tree cavities, becoming active hunters after sunset. They are territorial throughout the year, defending their space with loud hoots and actively chasing away intruders. This territorial aggression, especially from females, intensifies during the nesting season, sometimes leading to them striking intruders with their feet. Barred Owl pairs are believed to mate for life, raising one brood annually. Their nests can be vulnerable to predators such as larger owls, hawks, weasels, and raccoons. When disturbed at their nest, parent owls might flee, perform a distraction display with quivering wings, or even attack. Other bird species recognize Barred Owls as predators and may mob them collectively. The Great Horned Owl is considered their most significant predator, preying on eggs, young, and occasionally adult Barred Owls.
Conservation Status and Considerations
The Barred Owl is currently considered a species of low conservation concern, with fairly numerous populations. Between 1966 and 2019, their populations saw an annual increase of approximately 1.1%. Global breeding populations are estimated at around 3.5 million. Historically, Barred Owls were confined to old, undisturbed forests in eastern North America. However, factors such as fire suppression and tree planting initiatives have facilitated their northward and westward expansion. They have spread to the West Coast, where they now compete with and sometimes displace the native Spotted Owl, raising concerns for the latter’s conservation.
Barred Owls’ reliance on mature forests with large, dead trees for nesting makes them sensitive to logging activities. Consequently, they are often utilized as an indicator species for managing old-growth forests. Their presence and habitat requirements highlight the importance of preserving these vital ecosystems.
References
- Lutmerding, J. A. and A. S. Love. (2020). Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.
- Mazur, Kurt M. and Paul C. James. (2000). Barred Owl (Strix varia), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.
- Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.
- Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2017). The North American Breeding Bird Survey, Results and Analysis 1966–2015. Version 2.07.2017. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.
- Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.
