The short-eared owl (Asio flammeus) is a fascinating bird of prey that is found throughout much of the world. One of the most interesting aspects of this owl is how it is able to fly and hunt so effectively. In this article, we will take an in-depth look at the short-eared owl’s wings and flight capabilities and examine what makes this owl such an adept flyer.
Anatomy of the Short-Eared Owl Wing
The wings of the short-eared owl have several key anatomical adaptations that enable powerful, silent flight. Some of the most important features include:
Large Wing Surface Area
The short-eared owl has proportionately large wings for its body size. The wingspan ranges from 33-42 inches, which provides a lot of surface area to generate lift and thrust during flight. The large wing size allows the owl to fly slowly and maneuver tightly without stalling.
Lightweight Bone Structure
The wings contain lightweight, hollow bones which help reduce overall body weight. This is important because less weight means the owl has to work less hard to fly. The light bone structure also minimizes inertia so the owl can flap its wings more quickly and change directions rapidly.
Soft Feather Edges
The leading edges of the owl’s wings are fringed with soft, pliant feathers. These help dampen and muffle the noise from air rushing over the wings during flight. This allows the owl to fly and hunt by ear without making much sound.
Fringe of Comb-Like Feathers on Trailing Edge
The rear edge of the wing has a fringe of comb-like serrations formed by the owl’s flight feathers. These help provide lift and allow the owl to fly very slowly without stalling. The comb-like feathers also further dampen noise and turbulence.
Large Slotted Wing Tips
The tips of the short-eared owl’s wings are long and tapered, with slots or notches between the feathers. This configuration spreads airflow smoothly off the end of the wings, eliminating wingtip vortices. This improves aerodynamics and prevents turbulence and noise.
Short-Eared Owl Flight Capabilities
The short-eared owl’s unique wings provide it with some very impressive flight capabilities including:
Slow Speed Flight
The large wing surface area combined with the slotted wing tips and fringed trailing edge allow the short-eared owl to fly incredibly slowly. It can hunt by kiting or hovering in place above prey before dropping down to strike. Most owls are not capable of such slow flight.
High Maneuverability
Between the short, rounded wings and light bone structure, the short-eared owl is highly agile in flight. It can twist, turn, dive and change directions rapidly, which aids in chasing down prey.
Noiseless Flight
The soft leading edge feathers and comb-like trailing edge fringe make the short-eared owl’s flight virtually silent. This stealth helps it sneak up on prey without being heard.
Efficiency in Open Habitats
While many owls prefer forested areas, the short-eared owl has wings adapted for more open habitats like grasslands, marshes and tundra. It can fly efficiently over long distances in search of prey.
High Speed Captures
When needed, the short-eared owl can make swift plunging dives to snatch up prey on the ground below. Its damping feathers allow it to reach high speeds without making much noise.
Short-Eared Owl Hunting Techniques
The short-eared owl relies on its wing adaptations and flight capabilities to utilize some very effective hunting techniques:
Slow Hovering Flight
The owl will frequently hover or kite 20-60 feet above the ground while hunting, its wings held in a deep V-shape. This lets it spot prey while expending minimal energy.
Cruising and Quartering Over Hunting Ground
The owl will also cruise back and forth over open terrain on angled passes, watching and listening for prey rustling in vegetation below. This is called “quartering”.
Stealthy Approaches
Thanks to silent flight, the owl can approach prey very closely without making a sound. This lets it get within striking distance before prey realizes what is happening.
Sudden Drops onto Prey
From a hovering or cruising position, the owl will drop swiftly and directly onto observed prey below, reaching speeds of over 20 mph. Large prey is pinned down with the owl’s talons.
Low Speed Maneuvering Chases
The short-eared owl is capable of making tight, low speed turns. It uses this maneuverability to chase and grab fleeing prey.
Unique Flight Adaptations
The short-eared owl has several unique flight adaptations not found together in other owls:
Largest Ear Tufts
This owl has the largest ear tufts of any owl, about 1.5 inches long. These may help improve flight aerodynamics.
Longest Legs
The legs are elongated to reach down and grab prey while flying low over the ground.
Dark Streaking on Underwings
Bold dark streaks camouflage the underwing surfaces to make the owl less visible from below.
Cat-like Face
A flat face and yellow eyes gives the owl a facial appearance similar to a cat. This may help with precise binocular vision while hunting.
Notch in Upper Beak
There is a notch or concavity on the upper mandible that may aid in sound localization.
Migration and Global Range
The short-eared owl has one of the most extensive global ranges of any owl species thanks in part to its efficient flight ability. It can be found on every continent except Australia and Antarctica. However, it is still dependent on certain habitats.
Breeding Range
During breeding season, short-eared owls are found throughout the Northern Hemisphere in areas with open grassland, prairie, meadows, or tundra.
Region | Specific Breeding Areas |
North America | Grasslands of western and central Canada and United States |
Europe | Grassland and tundra from Britain eastward across Eurasia |
Asia | Russian tundra east to Chukotka plus Mongolia and northeastern China |
Wintering Range
In winter, short-eared owls migrate south to open habitats throughout North and South America.
Region | Winter Range |
Western North America | Southern Canada and northern United States south to Mexico |
Eastern North America | Southern half of United States south to Florida and Gulf Coast |
South America | From southern Brazil and Argentina northward up Andes and southward to Tierra del Fuego |
Nomadic Outside of Breeding Season
During fall and spring migration periods, short-eared owls become almost nomadic. They wander great distances and may turn up almost anywhere suitable habitat exists.
Threats and Conservation
While still widespread, short-eared owl populations face a number of conservation threats:
Habitat Loss
Conversion of grasslands and native prairie to agriculture is depriving the owls of essential nesting and hunting grounds.
Climate Change
Changing precipitation patterns may make prey less abundant in key breeding regions like the Arctic tundra.
Road Mortality
Short-eared owls that nest and roost on the ground are vulnerable to being struck by vehicles.
Pesticides
Chemicals and rodenticides applied in agricultural areas accumulate in owls and reduce reproduction.
Population Trend | Declining in North America, Europe and Asia |
IUCN Conservation Status | Least Concern |
CITES Listing | Not listed in CITES appendices |
More protected reserves of suitable habitat need to be established to ensure robust short-eared owl populations into the future. Only through concentrated conservation effort can this masterful flyer be preserved.
Conclusion
In summary, the short-eared owl is uniquely adapted for powerful but silent flight. A large wing surface that dampens noise, combined with a lightweight build and specialized feathers, allows this owl to hover, glide, dive and maneuver through open habitats in pursuit of prey. Evolution has shaped the short-eared owl into one of the most aerial owls, but it still faces substantial habitat and mortality threats. Maintaining populations of this specialized flyer will require a commitment to protecting the grassland and tundra ecosystems it depends on. With the right conservation measures, the short-eared owl will continue its aerial mastery for generations to come.