The short-eared owl (Asio flammeus) is a medium-sized owl found throughout the world. Their numbers have declined in many areas, leading to conservation concerns. In the opening paragraphs, we’ll provide quick answers to key questions about the status of the short-eared owl population.
What is the short-eared owl?
The short-eared owl is a medium-sized owl with prominent ear tufts that are usually not visible. They have boldly streaked brown plumage that provides camouflage when roosting. Short-eared owls hunt mostly small mammals, birds, and insects. They are found in open habitats like grasslands, marshes, and tundra.
How many short-eared owls are there globally?
Globally, short-eared owl populations are estimated at about 1 million to 10 million individuals. However, their numbers have declined by 30-79% over the last 40 years in North America and locally in parts of Europe and Asia.
Why are short-eared owl populations declining?
The declines are attributed primarily to habitat loss as grasslands and marshlands have been converted to agriculture and developed areas. Use of pesticides and rodenticides has also reduced their food supply. The owls are also vulnerable to collisions with vehicles and wind turbines.
How many short-eared owls are left in the United States?
The US population of short-eared owls is estimated at less than 100,000 individuals. Breeding Bird Survey data indicates a decline of 2.76% per year from 1966 to 2015. It is listed as Endangered, Threatened, or of Special Concern in several US states.
Conclusion
While global populations are still likely in the millions, short-eared owls have experienced concerning declines, especially in North America. Conservation efforts focused on habitat protection and restoration will be key to stabilizing and recovering their numbers. Ongoing monitoring and mitigation of threats are also needed.
Background on the Short-Eared Owl
The short-eared owl (Asio flammeus) is a medium-sized owl belonging to the typical owl family (Strigidae). Some key facts about this species:
Names
– Also known as the short-eared grass owl or marsh owl
– Scientific name: Asio flammeus
– Named for its small ear tufts that are often not visible
Identification
– Length: 13-17 inches
– Wingspan: 35-42 inches
– Plumage: Streaked brown above, pale below with dark streaks
– Facial disk pale with bold dark rim
– Eyes yellow
– Short ear tufts often not visible
Range and Habitat
– Found on every continent except Antarctica
– Occupies open country habitats like grasslands, marshes, prairies, dunes, and tundra
– Sometimes utilizes agricultural areas and clearcuts
Diet and Hunting
– Feeds mostly on small mammals like voles, mice, rats, shrews
– Also takes small birds, insects, reptiles, and amphibians
– Hunts by flying low over open ground and hovering/plunging on prey
– Most active at dusk and dawn
Region | Population Estimate | Population Trend |
---|---|---|
Global | 1 million – 10 million | Likely declining but insufficient data for parts of Asia and Africa |
Europe | 34,000 – 62,000 pairs | Declining, endangered in parts of Western Europe |
North America | Under 100,000 individuals | Declining by 2.76% per year |
Reproduction
– Nests on the ground in depression lined with vegetation
– Lays 4-11 eggs, incubated for 21-37 days
– Young fledge at around 35 days
Population Status and Threats
The global population of short-eared owls likely numbers in the millions. However, the species has undergone declines in many parts of its range, including steep declines in North America.
Short-Eared Owl Population Declines
– Declined by 30-79% in North America in the last 40 years
– Breeding Bird Survey shows 2.76% annual decline from 1966-2015
– Listed as Endangered, Threatened, or Special Concern in multiple states
– Many local declines noted in Europe and Asia as well
Causes of Population Declines
– Habitat loss as native grasslands and wetlands converted to agriculture
– Loss of nesting habitat
– Reduced food supply due to rodenticide use and loss of prey species
– Vehicle collisions
– Increased predation
– Collision mortality from wind turbines
Conservation Status
– Listed as Least Concern on IUCN Red List
– Considered endangered at state/provincial level in many parts of its North American range
– Listed on Appendix II of CITES (limited trade controls)
– Identified as in need of continental conservation action in North American Waterbird Plan
Short-Eared Owl Population Monitoring
Regular monitoring of short-eared owl populations is necessary to track their numbers and assess the impacts of conservation efforts over time. Some key programs monitoring short-eared owls include:
Breeding Bird Survey
– Long-running annual survey coordinated by the USGS and CWS
– Volunteers conduct roadside counts across North America
– Provides population trend data through statistical analysis
– Indicates a 2.76% annual decline from 1966-2015
Christmas Bird Count
– Annual winter bird count organized by Audubon societies
– Volunteers conduct a one-day count within prescribed circle areas
– Provides snapshot of winter populations and distribution
State/Provincial Surveys
– Many states and provinces conduct periodic breeding surveys
– Used to determine population density in key habitats
– Track occupancy rates and reproduction at known nest sites
Migration Monitoring
– Visual and radar studies along Great Lakes and Atlantic coast
– Reveals timing, routes, altitudes and weather-related influences
– Cape May Observatory: 30+ years of counts in New Jersey
Limitations and Needs
– Breeding surveys inadequate across much of the northern range
– Lack of coordinated surveys in Mexico, Central and South America
– More complete count data needed for Asia and Africa
– Banding studies to reveal migration patterns and mortality factors
Short-Eared Owl Conservation Actions
A variety of conservation actions are necessary to stabilize declining short-eared owl populations and protect their habitat.
Habitat Protection and Management
– Protection of grasslands, prairies, wetlands, and tundra
– Sustainable grazing practices and haying schedules
– Restoration of native plant communities
– Establishment of native grasses and low vegetation
– Protection of nesting and roosting sites
Reducing Mortality Threats
– Mitigation of vehicle collision risks
– Shutdown of wind turbines during migration
– Rodenticide use restrictions
– Enforcement of illegal shooting prohibitions
Population Monitoring and Research
– Continued continent-wide breeding surveys
– Banding studies to understand movements and mortality
– Research on impacts of pesticides and climate change
Education and Outreach
– Programs to build awareness in local communities
– Engaging farmers, land managers and policy makers
– Citizen science initiatives to involve the public
Legal Protections
– Listing endangered populations under ESA and state laws
– Strict enforcement of take prohibitions
– International treaty obligations under CITES
Case Study: Short-Eared Owl Conservation in Canada
Canada is home to a significant share of the global breeding population of short-eared owls. Here is a look at conservation actions focused on the species in Canada:
Monitoring and Research
– Breeding Bird Survey provides population trend data
– Targeted surveys on the prairies and in the Arctic
– Banding reveals migration routes and wintering areas
Habitat Conservation
– Protection of mixed-grass prairie habitats in Manitoba
– Grassland set-asides under Canadian Agricultural Partnership
– Wetland conservation through Ducks Unlimited
Threat Mitigation
– Removing wind turbines from native prairie habitats
– Working with transportation agencies to reduce vehicle strikes
Legal Status
– Listed as Special Concern under the Species at Risk Act
– Provincially listed as Endangered in Nova Scotia
– CITES Appendix II listed to regulate international trade
Outreach
– Engaging landowners, farmers, and industry about beneficial practices
– Awards program for landowners who implement owl-friendly practices
Future Priorities
– Improved monitoring across the northern breeding range
– Mitigating impacts of oil sands development
– Expanding protected area networks on prairies and in Arctic
– Working with US counterparts on continental scale actions
The Outlook for Short-Eared Owls
Targeted conservation efforts are needed to reverse declining population trends in many areas. If appropriate actions are taken, the outlook for the species can improve.
Potential for Recovery
– Still has large global population size
– Capacity to reproduce and disperse to new suitable habitat
– Potential to respond to habitat creation and management
Hopeful Signs
– Recent population increases noted in some regions
– Expansion back into former breeding range in parts of Europe
– More habitat being protected and managed for owls
Remaining Concerns
– Ongoing habitat conversion is still removing nesting habitat
– Unmitigated mortality factors continue to pose threats
– Lack of population data across parts of the range
– Impacts of climate change remain uncertain
Future Outlook Summary
– Depends on continued monitoring and mitigation of threats
– Maintaining and restoring habitat connectivity will be key
– International cooperation needed for remaining knowledge gaps
– Reason for guarded optimism if conservation efforts can be expanded