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Long-eared Owl (Asio otus)
long eared owl

Long-eared Owl (Asio otus)

The Long-eared Owl (Asio otus), also known as the Northern Long-eared Owl, is a slender, medium-sized owl belonging to the Strigidae family. It is a widespread species, distributed extensively across Europe, Asia, the Middle East, North America, the far northern reaches of Africa, the Canary Islands and the Azores.

Physical Description

The Long-eared Owl, as an adult, is a brownish grey owl with an orangish facial disk, dark-streaked whitish underparts, a brown back and long ear tufts that distinguish this species from other owls when perched. The species is sexually dimorphic, as the female is larger and more colourful than the male.

This owl can weigh between 220 and 435 grams and stands 35 to 40 centimetres tall. It has large, rounded wings with a wingspan of between 90 and 100 centimetres, which can be noted in flight. Juvenile birds have downy feathers, giving them a fluffy appearance and a distinct ‘V’  mark on their face.

There is a marked difference in appearance between the North American and Eurasian populations. The birds found in North America are rather dark, looking more streaked and mottled, and they have yellow eyes. On the other hand, the Eurasian birds are paler throughout the body, but mainly on their faces and reddish eyes.

Vocalisations

Long-eared Owls are a quiet species compared to other owls, and they call predominantly during the breeding season when they produce a collection of songs and calls that have a variety of purposes. The typical male call can be described as a resounding “woop” repeated every two to four seconds in a series of up to 200 notes.

The sound produced can be heard more than one kilometre away. The female makes a high-pitched call at the nest, which sounds like a lamb’s bleat. Males and females also produce alarm calls ranging from dog-like barks to cat-like mews. When an owl is unsettled, they rapidly make a pop sound by closing their mandibles.

Both sexes can clap their wings together while flying, which produces a sound akin to a whip. Young birds also make begging calls.

Migration and Movements

Long-eared Owls are mostly resident within their breeding range, but birds living in the northern sections of their distribution are migratory to a large extent, moving south during Autumn. Owls may respond to decreases in food availability by becoming nomadic and moving to areas where food is available.

Long-eared Owl migration map
Range map by Birds of the World

Habitat

Long-eared owls occur in areas with a mix of tree coverage, with the ideal habitat being wooded areas with adjoining open shrublands or grasslands. The wooded areas mainly consist of coniferous and deciduous woodlands with watercourses and windbreaks.

The species has an extensive range in elevation, occurring from sea level to almost 2000m above sea level. The owls require different biomes for roosting and hunting. They roost during the day in the thick vegetation found in forests and hunt over the adjacent open shrublands and grasslands at night.

Long-eared Owl (Asio otus)

Diet

Long-eared Owls feed primarily on small mammals. The mammals include voles, shrews, mice, young rabbits, kangaroo rats, and pocket gophers. Small birds sometimes fall victim to the owls too.

The birds are caught on the ground or in low vegetation while roosting. Other animals recorded as prey items include bats, weasels, moles, chipmunks, squirrels, lizards and snakes.

They can catch prey items weighing as much as 100 grams, but most prey items weigh less than 60 grams.

Feeding Behaviour

Long-eared Owls are nocturnal creatures, so they are most active at night when they spend most of their time hunting. During the day, they roost in trees, often against the trunk. The owls are rarely active at dusk, but they hunt when they need to catch other food to feed their young.

The owls hunt by flying back and forth, close to open ground. In some instances, the owls may hover above prey or hunt from a perch, particularly during strong winds. They detect prey using both sight and sound. The owl pounces when a prey item is found by swooping down and grasping the animal in its talons.

The animal is killed by biting the back of the animal’s skull, and the prey is usually swallowed whole. Hunting usually takes place over open areas, but they are known to sometimes hunt underneath the tree canopy in areas with less tree cover.

Breeding Behaviour

Long-eared Owls breed during the boreal Spring and Summer months, from February to July. During Autumn and Winter, the owls congregate and establish roosting groups of up to 100 individuals. This species is monogamous, and courtship often starts at the end of winter when males start displaying to females before the birds disperse.

During the courtship phase, males partake in aerial courtship displays, which involve flying in a zigzag fashion over the nesting habitat and clapping their wings intermittently between glides.

Nesting

Long-eared Owls are not known to build their nests, so they most commonly utilise stick nests in trees made and abandoned by other bird species, such as crows, magpies, ravens, and hawks. Occasionally, the owls may use abandoned squirrel nests, cavities in cliffs, tree cavities or even nest on the ground.

Nesting pairs can sometimes be found nesting within 15 metres of each other, which are considered loose colonies. The nest is approximately 6.5 centimetres deep and 22 centimetres wide. Females only produce a single brood during the season. Broods usually consist of five to six white eggs, but females can lay as little as two eggs and as many as ten. The eggs are about 3.8 to 4.4 centimetres in length and 3 to 3.5 centimetres in width. The eggs are incubated for 26 to 28 days before they hatch.

Long-eared Owl (Asio otus)

The female stays in the nest during the incubation period, and the male catches prey to return to the female. Once the chicks hatch, the male is solely responsible for bringing them food and continues to bring food to the female, who remains with the chicks. At the end of the brooding period, the female leaves the nest to hunt and help the male bring additional food to the chicks. The owlets leave the nest three weeks after hatching and move onto surrounding branches. They become known as “branchers” since they no longer live in the nest but rather in the surrounding branches.

They move by hopping, jumping and even pulling themselves up onto branches using their wings and beak. The owlets start attempting their first short flights at five weeks of age. The owlets continue to be fed by both adults until they are six to eight weeks old when the female abandons them. That is followed by the male, who stops feeding the owlets after ten to eleven weeks. The newly fledged owlets reach reproductive maturity after one year, and from then on, they can repeat the process with their own young.

Mortality and Anti-predator Strategies

Adult Long-eared Owls have been recorded as prey items for several raptors, including Golden Eagles (Aquila chrysaetos), Great-horned Owls (Bubo virginianus), Red-shouldered Hawks (Buteo lineatus), Common Buzzards (Buteo buteo), Barred Owls (Strix varia), Red-tailed Hawks (Buteo jamaicensis) and Peregrine Falcons (Falco peregrinus). Nestlings are vulnerable to many predators, including raptors such as those mentioned above, crows, magpies, porcupines, raccoons and snakes.

To avoid being preyed upon, the owls roost against tree trunks. Their distinct morphological features, such as the ear tufts and elongated body, along with the cryptic plumage, allow them to camouflage against the tree, making them difficult to see.

Adult Long-eared Owls defend their young eggs by dive-bombing predators while producing alarm calls. In some cases, they may fake an injury to catch the attention of the threat and lead it away from the vulnerable nestlings or eggs. When the owls nest in loose colonies, many owls from other nests may defend the single nest under threat.

Unfortunately, the dangers that the owls cannot protect themselves against are those imposed by humans. Motor vehicle collisions and shootings kill many owls.

Conservation:

The Long-eared Owl is relatively common across its distribution range, but it is difficult to determine their population numbers and trends due to their nomadic movements and secretive lifestyle. Overall, it is thought that the size of the global population is decreasing due to habitat loss.

It has been noted, however, that the number of individuals varies yearly, making it difficult to establish an accurate population trend. However, the global population is estimated to be between 2,200,000 and 3,700,000 individuals making it a species of little conservation concern.

Long-eared Owl (Asio otus)

The owls require grassland or shrubland and woodland, ideally alongside each other, so the species is vulnerable to losing these habitats. The species may benefit from human disturbance, such as forest fragmentation, as this opens up spaces for the owls to hunt next to the woodland areas in which they nest.

Conclusion

The Long-eared Owl is a widespread species that feeds mainly on small mammals. It relies on wooded and open areas to be adjacent to each other to breed and hunt successfully.

The global population is not under severe threat. Still, management practices need to be implemented to conserve areas to prevent a further decline in the population size of the unique Long-eared Owl.