Short-eared owls (Asio flammeus) are medium-sized owls found throughout much of North America. They prefer open habitats like grasslands, marshes, and agricultural fields. Their habitat arrangements can vary based on region and season.
Breeding Habitat
During the breeding season, short-eared owls nest on the ground in dense, tall vegetation. This provides concealment and protection. Typical nesting habitats include:
- Grasslands
- Prairies
- Meadows
- Marshes
- Agricultural fields
They often nest in loose colonies. Nests consist of a scraped depression lined with grasses and feathers. Ideal breeding sites have abundant prey like small mammals and birds. They also require elevated perches like fence posts or small trees for hunting. The dense vegetation around nests ranges from around 12 inches to over 3 feet tall.
Wintering Habitat
During winter, short-eared owls expand their habitat range. They utilize more open areas with sparser vegetation. Typical wintering habitats include:
- Grasslands
- Agricultural fields
- Marshes
- Dunes
- Airports
- Rights-of-way along roads or railways
These open habitats provide better visibility and accessibility to prey. Short-eared owls are highly nomadic in winter. They will wander widely in search of abundant food sources.
Roosting Habitat
Roost sites provide protection from predators and weather. Short-eared owls roost on the ground, usually in dense, tall vegetation. They may also occasionally roost in:
- Bushes
- Small trees
- Fence posts
Sites that provide concealment are preferred, like ditches, depressions, or hollows. They tend to roost communally during winter for added safety.
Territory Size
Short-eared owls are highly territorial during the breeding season. They defend a territory around their nest. Estimates of territory size range from around 25-60 acres on average. Territory size likely depends on habitat quality and prey availability. More concentrated food resources allow for smaller defended territories.
Study Location | Average Territory Size |
---|---|
Oklahoma | 25 acres |
Idaho | 60 acres |
California | 35 acres |
Outside of the breeding season, short-eared owls are not territorial. They roams more nomadically over larger areas.
Home Range Size
The home range of short-eared owls varies based on season, habitat quality, and prey availability. A few key facts about their home ranges:
- Breeding home ranges are fairly small since most activity centers around the nest.
- Winter home ranges expand greatly. One study in Kansas found an average winter home range of 101 acres.
- In prime habitat with abundant food, home ranges may encompass just a few square miles.
- In suboptimal habitat, winter home ranges may extend over 600-700 square miles.
Due to the enormous variability, it’s difficult to pinpoint an average overall home range size. But home ranges are generally largest during winter and in less productive habitats.
Habitat Distribution and Density
The distribution and density of short-eared owls depends greatly on region, habitat, season, and food availability. A few key points:
- They are widespread and common across many areas of North America.
- Highest densities occur in prime habitats like prairies and coastal regions.
- Densities are lower in drier, desert-like interior regions.
- Some key habitats include the Great Plains grasslands, Pacific Northwest prairies, and Great Lakes coastal marshes.
- Population densities may reach up to 12 birds per square mile in ideal habitats during peak seasons.
- Across the species’ range, overall densities average around 1-3 birds per square mile.
Short-eared owl numbers fluctuate greatly between seasons and years depending on environmental conditions. Harsh winters and low prey availability can cause seasonal movements and declines.
Ideal Habitat Conditions
The key habitat components for short-eared owls include:
- Open areas – Grassy fields, marshes, meadows, and prairies provide optimal hunting grounds.
- Scattered perches – Scattered trees, fence posts, or other perches are used for observation when hunting.
- Prey abundance – voles, mice, birds, and other prey need to be readily available.
- Concealment for nesting – Dense, tall vegetation is needed for nesting and roosting cover.
- Minimal human disturbance – Short-eared owls avoid areas of heavy human activity and development.
Key Habitat Threats
Some of the major habitat threats facing short-eared owls include:
- Conversion of grasslands and fields to agriculture – Removes nesting and hunting grounds.
- Development – Destroys and degrades natural habitat.
- Drainage of wetlands – Diminishes marshes used for nesting and foraging.
- Reforestation – Reduces amount of open habitat.
- Habitat fragmentation – Breaks up contiguous habitat needed for successful breeding.
- Climate change – Could affect range and prey populations.
Habitat Conservation
Some recommend conservation practices to preserve short-eared owl habitat include:
- Protection of remaining native grasslands and wetlands – Critical for breeding habitat.
- Sustainable grazing practices on public/private lands – Maintains appropriate grassland habitat structure.
- Restoration of wetlands and native vegetation – Increases habitat acreage.
- Buffer zones around nesting sites – Reduces human disturbance.
- Delayed haying of fields – Allows time to complete nesting.
- Setting aside unused strips/sections of agricultural fields – Provides undisturbed nesting habitat.
Conclusion
In summary, short-eared owls utilize a variety of open habitat types depending on season, region, and food availability. Dense grasslands and marshes are critical for nesting and concealment. More open habitats like grasslands, agricultural lands, and wetlands provide optimum hunting grounds. Sufficient food resources and availability of undisturbed nest sites are key habitat requirements. Conservation efforts aimed at preserving native grasslands and wetlands can help safeguard the habitat these owls need to thrive.