The short-eared owl (Asio flammeus) is a medium-sized owl found throughout much of the Northern Hemisphere. They are known for their cat-like facial disc, streaked brown plumage, and distinctive ear tufts that are often not visible. Short-eared owls inhabit open grasslands, prairies, meadows, and marshes where they hunt small mammals, birds, and insects.
While short-eared owls have a widespread distribution, their populations have declined in many areas, leading to them being listed as endangered, threatened, or a species of special concern in some states and provinces. However, on a global scale, the short-eared owl is currently categorized as Least Concern by the IUCN Red List. This article will examine the current conservation status of the short-eared owl and reasons why their populations are declining in parts of their range.
Short-eared Owl Classification and Population Trends
The short-eared owl is one of the most widely distributed owls in the world and can be found on every continent except Australia and Antarctica. They are classified as follows:
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Strigiformes
Family: Strigidae
Genus: Asio
Species: A. flammeus
Globally, the short-eared owl is not considered threatened and is listed as Least Concern on the IUCN Red List with an estimated population of over 5 million adults. However, data from the North American Breeding Bird Survey shows that short-eared owl populations declined by 1.35% per year between 1966 and 2015. The 2016 State of North America’s Birds report listed the short-eared owl as a Common Bird in Steep Decline with a population loss of 2.77% annually over the past 40 years.
Population Status by Region
Here is a table summarizing the conservation status of short-eared owl populations in different parts of their range:
Region | Population Trend | Conservation Status |
---|---|---|
Global | Declining but widespread | IUCN Least Concern |
United States and Canada | Declining | Not federally listed but endangered, threatened, or special concern in several states and provinces |
Mexico | Unknown | Not listed |
Europe and Russia | Declining but widespread | IUCN Least Concern |
Asia | Unknown | Not listed |
This table shows that short-eared owl populations face the greatest pressures in parts of North America, where they are declining more rapidly than on a global scale. However, there are still millions of individual short-eared owls worldwide.
Threats and Habitat Loss
What are the major threats causing short-eared owl populations to decline in many parts of their range? The main causes appear to be:
- Habitat loss and degradation – The conversion of grasslands and prairies to agriculture, overgrazing, urban development, and reforestation have reduced the amount of suitable habitat for short-eared owls. They require large open spaces to hunt.
- Climate change – Climate shifts may affect prey availability and nesting success. More frequent droughts could potentially reduce habitat suitability in parts of their range.
- Vehicle collisions – Short-eared owls’ low, hovering hunting behavior makes them vulnerable to being hit by vehicles when nesting or feeding near roads.
- Human disturbance – These owls avoid nesting near areas of heavy human activity and infrastructure. Human disturbance can lead to nest abandonment.
- Poisoning – They may be poisoned by ingesting pesticide-laced prey or lead fragments from gunshots embedded in carcasses.
Habitat degradation and loss likely poses the most significant threat to short-eared owl populations. A 2022 study published in Avian Conservation and Ecology found that only 22% of the historical short-eared owl breeding range in Canada and the U.S. still contained suitable habitat. Most habitat loss has occurred in the Midwest and northeastern regions.
Habitat Requirements
Short-eared owls require the following habitat conditions:
- Open grassy areas – grasslands, prairies, meadows, marshes, peatlands
- Herbaceous vegetation up to 1 meter in height
- Scattered shrubs and trees for roosting
- Ample prey populations of small mammals and birds
- Minimal human disturbance
They may occasionally inhabit agricultural areas and ranch lands if suitable protected nesting habitat is nearby. Most habitat loss has occurred through the conversion of native grasslands to intensively managed agricultural land.
Legal Protections
The short-eared owl is protected under the Migratory Bird Treaty Act in the U.S. and Canada, which prohibits harming or killing the birds, eggs, or active nests without permits. Here are some specific legal protections:
United States
The short-eared owl has no federal endangered species status in the U.S. However, it is listed as endangered, threatened, or special concern in these states, which prohibits harming the owls or habitat:
- California – Species of Special Concern
- Colorado – Threatened
- Connecticut – Endangered
- Massachusetts – Endangered
- Michigan – Threatened
- Montana – Species of Concern
- New Jersey – Threatened
- New Mexico – Threatened
- New York – Endangered
- Oregon – Sensitive Critical
- Washington – Candidate
Canada
The short-eared owl is listed as threatened, endangered, or special concern in these provinces:
- Alberta – Sensitive
- British Columbia – Red-listed
- Manitoba – Threatened
- New Brunswick – Vulnerable
- Newfoundland – Vulnerable
- Nova Scotia – Endangered
- Ontario – Special Concern
- Quebec – Vulnerable
- Saskatchewan – Threatened
Providing legal protections makes it illegal to harm short-eared owls or their habitats in parts of their range experiencing population declines. However, protections are still limited to prevent further habitat loss.
Conservation Efforts
While habitat loss is difficult to reverse in much of the short-eared owl’s core range, some conservation actions can help stabilize populations:
- Protecting remaining grasslands from conversion to agriculture or development
- Managing grasslands to maintain vegetation heights preferred by short-eared owls
- Establishing protected reserves and minimizing human disturbance near nesting areas
- Installing nest boxes to provide additional secure nesting sites
- Enforcing legal protections and mitigating industry impacts near nesting areas
- Reducing rodenticide use to prevent poisoning from contaminated prey
- Monitoring population trends to identify declines requiring intervention
Some habitat restoration efforts have also reestablished native grasslands on underused farmland, providing increased suitable habitat in degraded landscapes. For example, the American Prairie Reserve in Montana aims to restore over 3 million acres of prairie grassland partly to benefit short-eared owls and other grassland-dependent species.
Conclusion
In conclusion, the short-eared owl has an extensive global range and large total population size. However, habitat loss and degradation have caused regional population declines, especially in the Midwestern U.S. and Canada. While not currently threatened worldwide, the short-eared owl is endangered or a species of concern in several North American states and provinces. Ongoing conservation efforts to protect remaining habitat and reverse grassland loss in parts of their range are needed to ensure stable long-term populations of this owl into the future. The short-eared owl serves as an indicator species for the health of these fragile grassland ecosystems.