The short-eared owl (Asio flammeus) is a medium-sized owl found throughout much of the Northern Hemisphere. As their name suggests, short-eared owls have small tufts of feathers on the top of their heads that often are not visible. These owls prefer open habitats like grasslands, marshes, and tundra where they hunt for small mammals, birds, and insects.
Short-Eared Owl Habitat Requirements
Short-eared owls require large, open expanses of habitat for breeding, roosting, and hunting. They are found in a variety of open habitats including:
- Grasslands
- Prairies
- Meadows
- Marshes
- Agricultural fields
- Tundra
- Dunes
- Moorlands
The key requirements seem to be open terrain with low vegetation that allows for easy hunting. Short-eared owls are usually found in areas with plant heights less than 1 meter tall. They require these open habitats to hunt, often by hovering and gliding low over the ground listening for prey. The owls will also use fence posts and other elevated perches to scan for prey.
Breeding Habitat Size
During the breeding season, short-eared owls require large swaths of open habitat for nesting and raising young. Most research suggests they require at least 30-60 hectares of contiguous habitat for nesting and foraging requirements. The table below summarizes some habitat size estimates from different studies:
| Study Location | Estimated Breeding Habitat Size |
|---|---|
| Scotland | 50-100 hectares |
| Netherlands | 20-50 hectares |
| Ohio, USA | 30-40 hectares |
| Colorado, USA | 60 hectares |
These habitat size estimates indicate short-eared owls require fairly large, contiguous areas of suitable habitat for nesting and raising young during the breeding season. The specific habitat size needs likely depend on prey abundance and availability in that region. But in general, it appears short-eared owls need at least 30-60 hectares of suitable habitat for successful breeding.
Wintering Habitat Requirements
During the non-breeding season, short-eared owls are often more flexible in their habitat needs. Some key facts about their wintering habitat requirements include:
- They will use a variety of open habitats including grasslands, marshes, dunes, agricultural areas, and meadows.
- Home range sizes vary from around 200 hectares up to over 600 hectares.
- They are often loosely territorial during winter, with home ranges overlapping.
- Habitat patches as small as 5-10 hectares may be used for roosting and hunting.
- Larger habitats with more small mammal prey are preferred.
So while short-eared owls continue to rely on open habitats during winter, they are much more flexible and able to utilize smaller habitat patches. Their home ranges expand and they are not strictly territorial. Smaller areas can be used for roosting and foraging as long as prey is abundant.
Why Large Open Habitats Are Important
There are several reasons why short-eared owls rely on large open expanses of habitats like grasslands, marshes, and tundra:
- NESTING REQUIREMENTS – They nest on the ground in dense, tall vegetation that provides cover and concealment. Large habitats have more nesting options.
- HUNTING REQUIREMENTS – Their low, hovering, gliding hunting style works best over open areas with low vegetation. Small, dense areas would inhibit hunting success.
- PREY ABUNDANCE – Large open habitats support higher populations of small mammal prey like voles, lemmings, and mice. More prey availability means higher owl productivity.
- SECURITY FROM PREDATORS – Open environments allow owls to readily spot approaching predators. Dense vegetation would provide cover for predators to ambush nests.
Having sizeable, contiguous areas of open habitat provides short-eared owls with ample nesting sites, hunting grounds, prey availability, and security from predators. In particular, large habitats provide essential resources for breeding and raising young owls.
Threats to Short-Eared Owl Habitat
Unfortunately, many of the open habitat types preferred by short-eared owls have declined significantly over the past century. For example, it is estimated over 99% of tallgrass prairie habitat in North America has been lost. This habitat loss threatens short-eared owl populations. Some specific threats to their habitats include:
- Conversion of grasslands and prairies to agriculture or development
- Succession of open habitats like meadows into woodlands
- Wetland drainage and degradation
- Habitat fragmentation – open areas become separated into smaller parcels
- Fire suppression – allowing vegetation to become denser
- Nest destruction by agricultural operations
All of these factors have led to less suitable habitat available for short-eared owls across their range. With less open habitat, they have fewer places to successfully nest, roost, and hunt.
Habitat Conservation Recommendations
To protect remaining short-eared owl populations, the following actions can help conserve suitable habitat:
- Preserve large grasslands, prairies, meadows, and wetland habitats through conservation easements and land protection
- Manage habitats with prescribed fire, mowing, or grazing to maintain open vegetation structure
- Restore native grasslands and wetland habitats in former habitat areas
- Establish buffer zones around known owl nesting areas to protect sites
- Delay haying of grasslands until after owl nesting season
- Provide perches like fence posts for hunting and surveillance
- Educate landowners and farmers about owl habitat needs and how to protect sites
Adequate habitat is essential for short-eared owl survival and reproduction. Protecting and managing remaining open habitats will give these owls the open expanses they need to nest, roost, and sustain viable populations into the future.
Conclusion
In summary, short-eared owls require sizable areas of open habitat like grasslands, marshes, and tundra. Research indicates they need at least 30-60 hectares of contiguous habitat for successful breeding. Large open habitats provide nesting sites, hunting grounds, abundant prey, and protection from predators – resources critical for owl reproduction. Unfortunately, extensive loss of open habitats threatens short-eared owl populations. Habitat conservation through preservation, management, restoration, and increasing landowner awareness will be key to sustaining these fascinating owls that depend on wide open spaces.
