Long-eared owl

Appearance

This species is a rather slim and long winged owl with usually prominent erectile ear tufts, which are positioned closer to the center of the head than in many other types of owl. The purposes of ear tufts are not definitively known and are present in about half of living owls. Arguably the most popular theory amongst biologists and ornithologists is that ear tufts could be a means of intraspecies communication of intent and mood. In general coloration, the long-eared owl is often considered a hue of ochraceous-tawny with a grayish or brownish wash variably manifesting. The base color is commonly overlaid with variable blackish vertical streaks, which are usually more apparent about the wings and back. The scapulars are usually marked whitish, which provide further contrast when seen against the base color and blackish markings. The wing's dark carpal patches can also display broad panels of buff or almost orange on the wings across the base of primaries, which represent a more richly emphasized version of a pattern shared with other owls that tend to be vole-hunting specialists, like short-eared owls and great gray owl. On the underside, the body tends to be a somewhat paler ochraceous-tawny compared to the upperside. Long-eared owls tend to have dusky streaks on the upper breast, below which they may be heavily marked with herring bone pattern. There is much individual and regional variation in markings with owls dwelling in more extensively forested regions tending to be of a darker hue, often so densely washed above as to appear largely dusky brown on the back and the underside largely overlaid with bolder dusky-blackish marks. Meanwhile, in some desert-like regions, the plumage may tend towards a somewhat more washed out look, at times appearing fairly cream or yellowish, with sparser and lighter dusky markings overall. The facial disc is visibly well developed and variably colored in the species, rimmed dusky often with white running down along the center through the bill, while at times the white lines form a “moustache” and/or extending to the inside of the facial disc rim. The ear tufts are usually dusky in front and paler tawny on the back. Long-eared owl possess a blackish bill color while its eyes may vary from yellowish-orange to orange-red, tarsi and toes feathered.

The long-eared owl is a medium-sized owl, which measures between 31 and 40 cm in total length. Their wingspan is relatively large for their size, measuring 86 to 102 cm. However, compared to other widespread owls considered of medium size and to which they can appear broadly similar in size, such as barn owl, short-eared owls and tawny owls, the long-eared owl is quite a bit lighter and slenderer bodied, with mature weights around half of those of tawny owls not being uncommon. As expected in owls and birds of prey in general, long-eared owls display reverse sexual dimorphism in which females are usually slightly larger than males. Males furthermore may tend to be somewhat paler in plumage than females. In Finland, one survey of the body mass of mature birds found that 22 males averaged 288 g while 20 females averaged 327 g. In body mass, European long-eared owls per a study were shown to run contrary to Bergmann's rule as body mass seemed to increase further south, being lightest in Sweden, where 37 males averaged 197 g and 24 females averaged 225 g, intermediate in Denmark and heaviest in the Netherlands, where 21 males averaged 256 g and 24 females averaged 308 g. In migratory owls largely from Scandinavian summer grounds in England, the average weight of 8 males was 263.6 g and the average of 28 females was 294.7 g. Meanwhile, in various studies in North America, 38 males were found to average 245.3 g, 55 males to average 261 g and 15 males 232 g. From the same studies, respectively, 28 females averaged 279.4 g, 49 females averaged 337 g and 19 females averaged 288 g. Museum specimens in North America were found to average 245 g in 38 males and 279 g in 28 females, while 520 migrating adults in Duluth, Minnesota averaged 281.1 g. In all, long-eared owl males may vary in weight from 160 to 330 g while females may vary from 180 to 435 g.

In standard measurements, long-eared owls vary in wing chord length from 262 to 315 mm in males, with 883 in North America averaging 285.1 mm, and 255 to 332 mm in females, with 520 American ones averaging 286.2 mm. The tail may measure 121.5 to 161 mm in males and 143.5 to 165 mm in females, with 1,408 owls averaging 146.3 mm. Less widely measured are bill length, which averaged 15.7 mm in males and 16.2 mm in females from North America, and tarsus length, which averaged 38.2 mm in 20 males and 39.9 mm for 16 females from Europe, with a range in both sexes of 36.9 to 42.3 mm. In terms of their skeletal structure, it bears a relatively wide skull but relatively small eyes and orbits, while the beak is relatively elongated but weak. The legs are relatively long and thin and, while needle-sharp, the talons are relatively fine and the feet relatively weak for an owl. However, the talons are still highly proficient at drawing blood if contact is made with human skin.If seen well, an experienced observer is usually able to distinguish a long-eared owl by combination of its field marks, size and coloration. However, some potential owl species may be confused for them. The Stygian owl is larger with partially bare toes and generally darker with inky and more boldly patterned plumage, with often nearly the enter facial mask appearing off-black. Tawny owls, which co-exist with long-eared owls in Eurasia, are unlikely to be mistaken given that they usually appear considerably rounder and bulkier overall, and possess a much broader, more rounded head. The tawny owl has no ear-tufts, eyes of blackish-brown colour and relatively shorter wings. In flight, tawny owls show well-fingered primaries unlike the squared off wings of the long-eared owl. The Eurasian eagle-owl is far larger and more massive than a long-eared owl with visibly more overdeveloped and powerful-looking feet and talons and a huge squared-off-looking head with the ear-tufts set nearer to the edge. The eagle-owl is often more heavily patterned on the crown and back with heavy blackish marking but has a less strongly demarcated facial disc when compared to the long-eared owl. In some parts of the wintering range, other eagle-owls may scarcely abut the wide range of long-eared owls in Eurasia but are usually distinguishable by size differences, plumage characteristics and, occasionally, habitat preferences. Asian fish owls, which are essentially a subset of eagle-owls, are generally also much larger than long-eared owls with tousled-looking ear-tufts, less variable coloring and often feathered over only part of their tarsi. In North America, great horned owls, yet another type of eagle-owl in all but name, have a squarish head and more widely separated ear-tufts. Like other "Bubo" species, great horned owls are also perceptibly larger and more massively built than any long-eared owl. Great horned owls also have typically heavily barred, rather than streaked, underparts. Scops and screech owls are much smaller than long-eared owls, as well as differently marked and usually having rather short ear-tufts. The Marsh owl is generally brown with quite different-looking fine mottling or barring below and has brown eyes and tiny ear-tufts.

Over much of its range, long-eared owls occur with the related short-eared owl, the latter species averaging slightly larger. Much has been written about distinguishing them in the field, though, if seen well, the resemblance between the species is not particularly strong. Furthermore, the two species differ in habitat preferences, with the short-eared owl often favoring any kind of entirely treeless, open habitats, often avoiding the edge habitats favored by the long-eared owl. However, in dim light, at a distance or in flight, confusion is certainly possible. In both long-eared and short-eared owls, the flight style when seen has a distinctive, erratic and buoyant flapping quality that many birdwatchers consider reminiscent of a moth. At rest, the ear-tufts of the long-eared owl serve to easily distinguish the two. The iris-colour differs: yellow in short-eared, and often orange in long-eared. Furthermore, the black surrounding the eyes is vertical and slight on the long-eared, and horizontal and far more conspicuous on the short-eared. Overall, the short-eared owl tends to be a paler, sandier-looking bird than the long-eared, lacking the darker and more extensive markings of the latter. There are a number of other ways in which the two species differ which are best seen when they are flying. Short-eared owls often have a broad white band along the rear edge of the wing, which is not shown by long-eared owls. On the upperwing, the short-eared owl's primary-patches are usually paler and more obvious. The band on the upper side of the short-eared owl's tail is usually bolder than that of the long-eared. The short-eared's innermost secondaries are often dark-marked, contrasting with the rest of the underwing. The long-eared owl has streaking throughout its underparts, whereas on the short-eared the streaking ends at the breast. The dark markings on the underside of the tips of the longest primaries are bolder on short-eared owls. The upperparts of short-eared owls are coarsely blotched, whereas on the long-eared they are more finely marked. The short-eared owl also differs structurally from the long-eared, having longer, slimmer wings. The shorter and broader wings in combination with a squarer tail in long-eared owls produce proportions more reminiscent of a buzzard than the short-eared owl. When studied by their osteological features, however, the long-eared and short-eared owls are difficult to distinguish.The long-eared owl has relatively large ear slits placed asymmetrically on the sides of its head, as in a majority of owls, with the left ear higher and right lower in order to allow them to absorb sound both from above and below. The ear slit very nearly occupy the full height of the skull, being are about 38 mm, long and covered in movable skin flaps. The right ear is about 13% larger based on freshly dead owls. Due to its ear structure, the hearing of a long-eared owl is around ten times better at hearing high and medium pitches than humans. Barn owls and boreal owl have roughly similar ear structures, with the relative size of the ear structure and facial disc in owls generally indicative of the level of importance of acute hearing to their life history. Owls with relatively smaller ear slits and shallower or vestigial facial discs tend to skew towards more crepuscular or partially diurnal behaviors, whereas owls such as long-eared owls are more or less entirely nocturnal. It is well known that a majority of owls can hunt in darkness due to their extraordinary hearing, which allows them to pinpoint locations of prey, but they can also utilize their hearing to track intraspecific calls and activities and avoid predation risks.

The vocalizations of this species are highly variable. Amongst owls of all ages, long-eared owls in Michigan were recorded to have made 23 different vocalizations. Karel Voous considered them to likely be the most diverse vocalists of all owl species in the Northern hemisphere. The song of the male long-eared owl is a deep "whoop", which is repeated at intervals of several seconds. It starts with some hoots at slightly lower pitch before reaching full volume and quality. On calm nights, this song may carry over up to 1 to 2 km away. The song of the male is around 400 hertz. In North America, some observers have considered the male's song as analogous to the deep cooing of band-tailed pigeons. Females gives a weaker, less clear and much higher pitched song with a nasal quality. In nearly all owl species, the females, despite being typically the larger sex, have smaller syrinx than the males and so tend to have less powerful voices. The call of the female is at times compared to a weak tin whistle and is only audible at close range, being about 4-5 halftones higher than the song of the male. Females usually call only in duet with male during courtship, but also when the nest is selected and around the beginning of incubation. In fact, close study has revealed that female calling may occur as frequently as every 2–8 seconds at times of night between nest selection and egg laying. Both sexes utter a cat-like, somewhat hoarse "jaiow" notes or high "yip-yip" notes, the latter reminiscent of a call made by barn owls. When disturbed near the nest holding young, both parents may utter a series of tinny tones, "watt-watt-watt-watt". During the period of courtship the male flies around and flaps its wing around, producing a clapping sound. During the display flight, the male may make as many as 20 claps. As with many owls, all ages may produce hissing sounds and bill snapping when they feel threatened, especially in the context of nesting. Fledging young call all with high-pitched, drawn-out notes, variously transcribed as "feek", "peeyee" and "pzeei", and are often likened to the noise of a gate swinging on a rusty hinge.

Distribution

The long-eared owl has an extremely large distributional range. In Eurasia, they are distributed from the Iberian Peninsula and the British Isles, in both of which they are found somewhat spottily but quite broadly, especially for an owl. From western France east through the remainder of Europe they are found nearly everywhere. Though still usually quite common in these areas, there are small spots where they do not usually occur in Italy, Austria and Southeastern Europe. In Scandinavia they are found only as a breeding species in about the southern two-thirds of Norway, Sweden and Finland while they usual persist year around in haunts in the southern tips of Norway and Sweden, respectively, as well as in all of Denmark. In coastal Norway they are found at their worldwide northern limit as breeding bird, with long-eared owls nesting as far north as in the Subarctic zone of Troms. In latitudinal range, they are found as far south the Azores, the Canary Islands while their limited breeding range in north Africa is from Morocco to Tunisia, as well as seemingly in northernmost Algeria. Out of Europe, they are found very spottily as breeders in Turkey, northernmost Syria, Israel and Lebanon. They are quite broadly distributed within Russia, breeding in about the southern two-thirds of the country and often occurring year around in about the southern third of it and east to Siberia, ranging far as Sakhalin. Their range is continuous from Russia into most of Kazakhstan, Georgia, Kyrgyzstan, about half of Uzbekistan and infrequently into northern Afghanistan and Turkmenistan. In the east, they range through most of Mongolia and the western and eastern parts of northern China, with seasonally uncertain status in the Koreas. Long-eared owls are found throughout the islands of Japan but mainly winter only in points south of Osaka. The long-eared owl occurs apparently only in winter in small spots of southern France, southern Greece, northwestern Egypt, northern Iran, southern Turkmenistan, broadly in much of Afghanistan, Pakistan and northern India, as well as to the east in Bhutan, southern China, Taiwan and most of South Korea. Irruptive wanderings have resulted in vagrant long-eared owls in various places such as the Faroe islands, Iceland and Madeira as well as Ryukyu Islands in the east.

This species is found widely distributed in North America as well. Their northern limits are reached in much of British Columbia, though they are mainly absent from the western and coastal part, with the breeding range scarcely spilling over into the southern part of the Northwest Territories. As is the case in most of Eurasia, they are usually found at up to 50 degrees north. Long-eared owls are also found breeding in most of Alberta, all but northern Manitoba and southern Ontario and Quebec only to the southernmost part of the Hudson Bay. However, with the exception of inland southern British Columbia, southern Alberta, and the southern parts of Ontario and Quebec, as well as an isolated population in Newfoundland, long-eared owls usually vacate their Canadian range during winter. The species range as a breeding species is far more extensive in the west than the east within the United States. They breed in Washington, Montana and North Dakota mostly continuously to much of California, where habitat is appropriate, Arizona, western Colorado and western New Mexico as well as less broadly in South Dakota and Iowa. Even though they are absent from the Pacific coasts in Washington and Oregon, they may be found breeding along the Pacific in southern California and even Baja California in Mexico. The first record of breeding for mainland Mexico was recorded for an incidental observed nest built by owls in Janos Biosphere Reserve in Chihuahua. They also breed and occur year around in most of Minnesota, Wisconsin and Michigan. Breeding and/or year around occurrence is very rare in the eastern U.S. with a few records of them nesting in Maine, Virginia and West Virginia. The long-eared owl occurs much more broadly in North America during the non-breeding season and may found essentially all over the Midwest, Texas and as far south in Mexico as Colima, Veracruz and northern Oaxaca. The species also occurs in the non-breeding season in Louisiana and much of northern Mississippi, Alabama, Georgia and South Carolina north to Illinois, Indiana, Ohio and southern Pennsylvania. Very rarely, these birds have turned up in Florida and, as a vagrant, even the Bermudas. They are found also by winter and in migration in much of the east coast of the United States, from the Outer Banks in North Carolina, broadly in eastern Pennsylvania and almost anywhere in Delaware or New Jersey, southeastern New York and north to much of southern New England including almost all of Connecticut, Massachusetts and Rhode Island as well as southern New Hampshire.

Behavior

Long-eared owls are more or less strictly nocturnal in activity. Usually activity for the species commences at dusk. After nightfall long-eared owls in Idaho were least active from 8-10 pm and from 5-6 am, while the hours around 10-12 pm and 3-5 am were often the peak times of activity. When living relatively close to the Arctic, long-eared owls may be forced to forage during daylight as no full nightfall may occur during summer. When flying by day, long-eared owls are often mobbed by diurnal birds such as corvids and other birds of prey. Often long-eared owls will discharge a fairly large amount of pellets and drop them below regular day roosts. Unlike most other owls, the species has no territorial hunting ground. In Switzerland, 14 long-eared owls examined using radiotelemetry were found to have an average home range of 980 ha. In the study, they required fields along borders of woodlands, avoiding completely treeless areas more so than they were prevalent in the environment. In the České Budějovice area of Czech Republic, 9 radiotagged owls were studied. Nearly equal numbers were found in suburban and urban areas, and urban ones used developed areas for more than 50% of their nocturnal activity while suburban ones used developed areas for less than half of their activities. Similar habitats were favored by both urban and suburban owls but urban owls had to range wider to avoid heavy human activity and access city parks and so had larger average ranges, 446 ha vs 56 ha, while suburban ones had easier access to meadows and stands of woods.During daytime, long-eared owls tends to roost in an upright position on a branch, not infrequently close to the trunk, oftentimes within dense foliage. In winter, the long-eared owl often stays close to the same tree or grove of trees. Usually, when approached, the owl freezes with its body stiffly upright, eyes closed to narrow slits and ear tufts erect. This is called the “tall-thin position” and is common to at least a couple dozen species of typical owl. If approached closed, the owls will alternately open and close their eyes, finally lowering ear tufts, fluffing body plumage and flying to another roost. Unlike most owls, which show a tendency towards territorial behavior on a fixed range year-around when possible, long-eared owls in the non-breeding season may form aggregations of owls while roosting. Such groupings may include 6 to 50 owls, with a European record of about 150 owls at a single roost. Even other migratory owls in the temperate zone do not tolerate each other as closely as do long-eared owls, with short-eared owls seemingly only forming aggregations when food supplies are exceptionally high, while social roosting in long-eared owls seems to occur regardless of local prey numbers. Long-eared owls tend to roost in the depths of the "darkest stands of trees" in order to conceal their presence, though they prefer being close to forested edge to allow access to hunting over more open ground. A study in the New Jersey Meadowlands area showed that roosting owls had a strong fidelity for certain trees, particularly conifers such as cedars where the main truck is large obscured from view and a grouping of at least 2-3 closely clumped trees occurs. Roost height in the New Jersey study was at 3 to 15 m or occasionally higher. In New Jersey, different roosts were preferred each year and in the local heavily modified environment, the owls become partially habituated to human activities. However, approach at closer than 3 to 4 m away usually caused them to flush. Departure of owls for nighttime hunting would generally occur between 40 and 49 minutes after sundown. Studies in the Moscow region of wintering roosts were done over 10 years, with 12 communal and 14 solitary roosts found. The communal roosts included up to 16 individuals per winter, with a mean of 9.9. Overall, the average in Moscow per roost site was 2.1 owls. Vole numbers the preceding year were likely the causes of numeric variations in years here while wind and snow avoidance were key in characteristics of roost sites. Extraordinarily large roosts were the norm in a study in Stavropol, Russia, where the general roost area could host from 80 to 150 individuals each winter over 4 years, with 93.7% of the roosts located in coniferous trees. In Milan, Italy, from 2 to 76 long-eared owls were observed per urban roost site. Here, nighttime observation showed that owls individually would depart the roost at peak during the darkest part of nighttime. A majority of the Milan roosting owls did not fly toward urban areas instead flying to suburban fields and forest where prey is more easily encountered. The reason for roosting in aggregations seems to be at least in part to mitigate predation risks.Long-eared owls may divide their hunting into phases, the first stopping around midnight, the second beginning some point after midnight and ending an hour before sunrise. While hunting, they tend focuses on the edge of woodlands, hedgerows and open spaces with rough grassland, and over young trees and open ground of all kinds. They hunt mainly on the wing, flying low and fairly slowly, often being quite low to ground, i.e. only around 150 cm. More often than visually finding their prey, it is thought that long-eared owls most often audibly detect the rustling of their intended food. In lab settings, long-eared owls were considerably more skilled at finding mice by sound in more or less complete darkness than tawny and barred owls, and in some American experiments even outclassed the auditorily-acute barn owls in this regard. Once prey is spotted, the long-eared owl's flight suddenly stalls, then they quickly drop with talons spread to pounce on prey that is perceived, or especially, that comes out into the open. Habitat may be perhaps even more key than prey numbers to the selection of hunting grounds. Often when prey numbers are more ample in timbered areas nearer the roost or rich marshy areas in the vicinity, the long-eared owls will still often come to more prey-poor areas such as old fields so that they can detect prey on open ground. The footspan of a long-eared owl, including claws, reaches on average 11.3 and 12.5 cm in males and females, respectively, which would be large for a diurnal bird of prey but is quite small for an owl of its size, given the physiological differences in the way different birds of prey tend to kill their prey. While acciptrid raptors tend to kill by stabbing with their talons through vital organs, owls are more likely to constrict their prey to death, so tend to have proportionately larger, more robust feet. In other medium-sized owls, the footspan in tawny owls and barn owls respectively averages 13.4 and 13.2 cm in between the sexes. Prey capture by long-eared owls was studied and compared to tawny owls in a European experiment. The two owl species caught mammals and beetles caught in similar ways but the long-eared owls shied away from flying sparrows and would only capture the sparrows when they perched. Long-eared owls either disregarded or killed but did not eat amphibians, while tawny owls did catch and eat amphibians when they were available. Occasionally the tawny owls would attack fish whilst one long-eared owl caught but did not eat a fish. The European study further revealed that several owls of different species ate bits of plant and did not appear to do so out of food deprivation or hunger.

Taken as whole, the global population of long-eared owls may appear to have a widely varying diet. One study accrued information from 312 studies from around the species' range. In total 478 prey species were found to be described, of which 180 were mammal species, 191 were bird species, 83 were assorted invertebrate species, 15 were reptiles, 7 were amphibians, and reportedly just a couple fish species. This included a total of approximately 813,033 prey items having been reviewed. However, on closer inspection, the long-eared owl generally appears to be something of a dietary specialist. It usually takes primarily, often nearly entirely, small mammals, e.g. rodents, as food in almost every part of its range. Usually a broad picture emerges that between 80 and 99% of the diet consists of mammals, averaging 94% in one estimate for all of Europe. However, in warmer, insular or more urbanized environments, a greater percentage or, rarely, even a majority of the diet can locally be non-mammalian prey. Mean prey sizes have been studied extensively and are almost always fall within a very narrow range. In Europe, the mean estimated prey size overall was 32.2 g. Meanwhile, in North America, mean prey sizes have varied between 30.7 and 37 g in two estimates. In general, throughout their range, the mean size of prey is generally encapsulated between 20 and 50 g, usually well under 40 g, and only in cases where long-eared owls, perhaps through lessened competition, has regular access to prey weighing 60 to 100 g or more, may the mean prey size range uncommonly reach 50 to 60 g. Cases of exceptionally large prey are mentioned where they occur below.

Reproduction

Long-eared owls tend to be monogamous breeders. Non-migratory populations are usually monogamous throughout the year, the pair bond being renewed annually. A study in Idaho determined that long-eared owls were locally extremely monogamous, with no extra-pair fertilizations were detected in 59 nestlings from 12 nests. There is a single record of a male breeding with 2 females in Netherlands, a very atypical case. Similarly, evidence of polyandry and alloparenting was found in a nest in western Montana where the four offspring of the female owl had two fathers, one of which was related to the female. Males claim their territory with singing and display flights with wing clapping. Singing normally starts at dusk on calm evenings and may continue through the night, clear windless moonlit nights are preferred. The song is usually delivered from a perch, most often at medium height in trees or from the upper half near the canopy, sometimes in flight. Males are responsive to playback during the period leading up to the breeding season, to such a degree 45% territories would've been undetected in Spain if males has not responded to recordings. Often between 8 and 50 pairs are recorded in different parts of the range in a typical range of 100 km2. In Scotland, about 17% of the 9-18 pairs per 10 km2 were non-breeders. Typical territories for pairs are 50 to 100 ha in Finland when voles are plentiful. Several pairs may nest rather close together nonetheless. The minimal distance is normally around 50 to 150 m between active nests, but in Idaho a nearest nest distance of only 16 m was recorded. When food is abundant, about 10-12 pairs, infrequently as many as 50, may nest within area of 100 km2. Pairs may tolerate each other in the same patch of trees while nesting if food supplies are abundant. A study in Province of Pisa of Italy of 32 territories found 10-15 pairs per 100 km2 with a mean nest spacing of 1,727 m. In a south-central Idaho study area, pair occurred on average 0.65 km apart. The highest densities may come from central Europe. The average density in central Europe is typically around 10-12 pairs per 100 km2. However, in Brandenburg, Germany, over a 24-year study, it was found the average density was 72.7 pairs per 100 km2. Based on studies from Michigan and Wyoming, anywhere from 10 to 100 pairs per 100 km2 was estimated, with the average range in Wyoming riparian habitat about 55 ha. Densities appeared lower in the Snake River area than elsewhere in southern Idaho. Globally, many pairs of long-eared owl occupy the same territory all year around but most prefer to use a different nest each year even if the same nest as last year is still in good standing. Females typically take on the duty of inspecting potential nesting sites and duets with its mate; perched on a chosen nest, she sings to contact the male, later vocal activity is confined to weak calls only heard at short range. During displays, females have also been recorded doing the wing clap display but much less intensely than males. Copulation tends to occur close to the nest. In Germany, it was recorded that the male precedes copulation with calls and display flights, followed by strong waving wing signals and tilting their body while perched near female and/or the nest. Copulation has also been observed on both the ground and the trees, preceded frequently by a duet, a male aerial display which ending in descent to ground and a flight by the female. Boundary fights between males are unrecorded in this species. Breeding occurs later in the year than sympatric species such as tawny owls and barn owls perhaps due to their more strongly migratory ways. Rarely mating may occur early as February in cooler temperate areas, but the pairs copulations usually take place in March or April. Winter breeding detected as new juveniles of 14–18 days of age were recorded in early February in Slovakia. Other prior reports of winter breeding are known from Italy, in two cases, as well as in the Czech Republic.

Normally nests in stick nest of large birds, i.e. "Corvus", "Pica", raptors and "Ardea" herons. Other nest builders in Europe can often include common wood pigeons and Eurasian sparrowhawks. In Britain and Finland 84% of 239 and 85 nest were made by carrion or hooded crows and Eurasian magpies. In England and Finland, 77% and 66% of the nest were in conifers, respectively. In Brandenburg, Germany, 90% of the nest were built by carrion crows and most were in "Pinus sylvestris". In different studies of Idaho, nearly all known nests were in old corvid nests. In one large study, nest heights, which averaged 3.2 m, and diameter of the nest construction, which averaged 22.3 cm, were deemed likely to be the most significant criteria for nest selection. In Ontario, conifers were usually used, often "Pinus" or "Juniperus", in corvid nests between 2.5 and 18.5 m high, but mostly between 5.5 and 9 m. Nest height averaged 6.7 m in Great Britain. In Slovenia, long-eared owls preferred coniferous trees for breeding, those that nested in deciduous trees had higher nest mortality especially earlier in the season due to higher predation rates. Similarly, nest site selection was largely correlated to predation risk in Spain, with ivy and tree canopy coverage less important than high scrub cover from below, in part because terrestrial predators were more common in the particular study area than aerial ones. In northeast Switzerland, nesting location are selected for anti-predator features, among 38 nesting sites, the ones seemingly preferred bore denser forest edges, greater canopy cover and were within conifers much more so than were prevalent in the overall environment, while the vicinities of buildings were avoided in the study area. An unusual case of urban breeding long-eared owls was observed in Moscow, Russia, where a loose colony was observed to form. The Moscow nesting was thought to be the result of synanthropization by the owls, in part due to lower predation risk in the urban areas versus rural vicinities. The mean distance of nesting owls in Moscow was 603 m whereas it was more than twice the distance in nearby rural areas. Tree nests are usually under 30 m above the ground, and can sometimes be so small that the wings and tail of brooding female may be visible from below. More infrequently than avian tree nests, leaf nests of tree squirrels, hawk nests in cacti and cliff nests of various birds may be used. While they usually take up already abandoned nest sites, sometimes long-eared owls are capable of chasing off prior occupant of nest even including other raptors indicative of their potential for fierceness and tenacity. Other than other bird's nests, alternate nesting sites have been used but appear to be usually rare or uncommon. Among these, are shallow depressions on the ground. Some ground nest locations recorded have included among heather, bracken and bramble, and even on reed beds, rabbit warrens. Some nests have been recorded in wicker baskets placed in trees for ducks. In North America, pairs of ground nest were found in each west-central Montana and in Okavagan, British Columbia, in all cases between the roots of or the ground immediate adjacent to the base of trees or bushes. Artificial nesting platforms made of twigs for the owls are also locally accepted. In Woodwalton Fen reserve of eastern England, 71 nests were built in wicker baskets set out for owls. Also in Yizre'el in Israel, 6 of 16 nest baskets hung in "Eucalyptus" were used by long-eared owls, with all occupied by February. In this general area of Israel, at least 72 other nest baskets for long-eared owls have been set out, to encourage the rodent controlling birds. Exceptionally, long-eared owls have nested in shallow cavities, in hollow willows or oaks, tree stumps or holes in cliffsides, however as a rule they tend to not be cavity nesters. 6.5% of 153 nests in Great Britain were on natural surfaces rather than animal nests. Nesting vicinities where previous attempts were successful are more likely to be reused, i.e. in Idaho where 48% of prior nesting areas were reused after successful attempts.

Egg-laying is between normally between late March and early May in most of the range. Egg laying dates in the northeastern United States, in a sample of 42 eggs, were between March 14 and May 30. Additional records in southern Canada show laying as occurring at as late as June 5. 43 eggs in Ontario were laid between March 19 to May 24, more than half between April 15 and May 5. In northern Italy, the mean egg laying date was March 27. Exceptional eggs were recorded as early as December 31 to January 3 in Spain. Re-nesting can occur within about 20 days after a clutch is lost. In Europe up to two broods have been successfully been raised at times of food abundance. Generally the female lays 3-5 eggs. Larger clutches are typical further north in the range. Record sized clutches have been recorded for Europe of up to 8 eggs in Sweden in years of a “vole plague” while record sized clutches worldwide were recorded of 10–11 in the Kazan area of Russia in similar conditions. In Great Britain, the average clutch size was recorded as 3.9 while in Germany it was 5.5 and, similarly, in Slovenia it was 5.6. In a study from Montana, the mean clutch size was 5. The pure white eggs are 40.2 mm × 32.5 mm on average in both North America and central Europe and weight about 23 g. At 1-5 day intervals, the eggs are laid on the bottom of nesting area. A clutch of 7 eggs takes 10 to 11 days to lay. Incubation begins with the first egg and continues for about 27–28 days. The female alone incubates while the male provides food, which is brought direct to nest. She may leave the nest early on to feed but does so much less later into incubation. A study in Montana found that corticosterone levels were considerably higher in adults of both sexes during the breeding season than during the non-breeding season, suggesting that the breeding season is more stressful on the owls.

The young hatch at 2 day intervals at any point between very late April and June. The average weight of 52 hatchlings in Montana was 18.4 g. Their eyes open at 5–7 days and they are brooded by the mother for about 2 weeks, often while the male perches nearby and watches over. The female alone feeds the chicks. In Idaho, the male was recorded to 2.5 times more prey deliveries during nesting than did the female. Injury feigning displays have been recorded at the nestling stage as an anti-predation measure. Usually long-eared owls are less bold in nest defense than some other owls, "Strix" owls for example, but they are capable of fierce protective attack nonetheless. Nesting defense by parents increased in Italy further into breeding season, with older nestlings being defended more vigorously. Females do a majority of nest defenses. Owl pairs incurring higher levels of regular disturbance are more likely to have a milder nest defense. During a defensive display, the parent ruffles up their plumage and partially spreads the wings to half open, trampling from one foot to the other, hissing and bill snapping and can look surprisingly large in this posture. If a perceived threat continues towards the owls, they may leap up and try to rake and grab at the threat with their talons. Even animals as large as humans may find themselves the victim of long-eared owl defensive attacks if they approach or, especially, if they climb up to a nest. The young leave the nest at 20–27 days of age but are initially flightless, often climbing about surrounding branches. At this stage they may be referred to as "branchers". Quite often the young fall to the ground, but they are usually able to climb back up using their claws and bill with heavy wing flapping. At dusk the begging branchers call to their parents with high pitched notes to indicate their location. At about 35–37 days, they are fully fledged and can fly well, but they often follow their parents and are fed by them for up to about 2 months, continuing to make high pitched calls. In Slovenia, independence was gained about 50–80 days after hatching, while in Idaho it was about 45 to 56 days.

Normally in North America the species produces one clutch per year, but 2 clutches in a year have been recorded in high vole years. An exceptional double brood was recorded in Idaho due to high food availability, allowing the pair to successfully raise all 11 nestlings to fledgling, while in same season 3 other females in same grove were able to produce an average of 5.3 fledglings in their single broods. Like other species using open nests, rather than enclosed cavities, the species has relatively short fledging period and quickly moves away from the dangerous situation of the nest site. Nesting success averaged 46% between two study years in a study of 112 nests in Idaho with raccoon predation considered the most serious cause of nesting failure. A different Idaho study of 24 nests showed that the owls fledged an average of 3.7 young per nest. In Montana, the mean number hatched per nest was 3.8 and mean number to have fledged per nest was approximately 2.2. 59% of 78 nesting attempts failed in Britain, with an average clutch size per successful pair of 3.91 to 4.53. 41 of 78 continuously monitored in this British study nest successfully produced 1 or more fledglings. In another British study, of 58 monitored pairs over 4 years, 83% laid eggs, 63% hatched one or more young, and 57% fledged young, with an average of 3.2 young fledged per successful nest. In yet another English study, this time exclusively of owls using wicker baskets, 50.7% of 71 attempts managed to fledge young. Among the wicker basket users, earlier nesters raised larger broods and had more fledglings than later, in part due to rising water tables making prey capture less ideal later in nesting season. For 6 pairs of long-eared owls using wicker baskets in Israel, the mean brood size was 3.6 and mean number of young owls to leave the nest was 3. At all stages and in all regions, reproduction tends to be more successful when prey populations are higher. In continental Europe, conditions are better than in England or Finland, perhaps due to the large population of common voles there that are absent in the more northerly countries, and nesting success averages higher. However, breeding success still is reliant on prey populations. In an 15 km2 area of southern Germany, one cold spring with few voles no breeding pairs were found. A year later, with a warm spring and many voles, 19 breeding pairs took up residence in the study area. First year mortality of long-eared owls has been calculated in Germany as 52% and 31%. In Brandenburg, Germany, of 867 breeding attempts, 36.6% pairs were successful in raising 1,468 young, which equates to 1.57 fledgling per all pairs that attempted, 4.31 per successful pair. The Brandenburg data shows that after 1990, when conservation minded farming initiative began, numbers increased significantly. Also in Brandenburg, in one case, 2 successive females to the same male were killed, the male mate was able to pair with a third female and resulting in a late successful fledging. In Slovenia, as studied between 1984 and 1993, of 79 nests, 32 produced young, 37 failed completely, and 10 failed after hatching. The Slovenian average number of owls hatched was 2.4 per nest and the average number of owls fledged was 1.6 per nest. In Pisa, Italy, long-eared owl pairs produced a mean of 0.95 per territorial pair and 2.13 per successful pair. In central Slovenia, 57 nests produced an average of 5.7 eggs per clutch. Of the 51 fledged owls, 31 died in the study, 22 of which were due to mammal and bird predation, 6 due to starvation, 2 due to road collisions and 1 drowned in ditch. In Britain, the most common diagnosed cause of nest failure was egg theft by humans. Banding studies show that the long-eared owl typically have a short lifespan, with more than 91% of 105 owls recovered in North America of determined age being 4 years or younger. The oldest recorded in these efforts was banded in New York and recovered in Ontario at the age of 11 years and 4 months. Another one may have been over 15 years old, however. One exceptional isolated record is known of a European long-eared owl of just under 28 years of age. Annual survivorship in Germany and Switzerland for adults is 69%.

Food

Long-eared owls may divide their hunting into phases, the first stopping around midnight, the second beginning some point after midnight and ending an hour before sunrise. While hunting, they tend focuses on the edge of woodlands, hedgerows and open spaces with rough grassland, and over young trees and open ground of all kinds. They hunt mainly on the wing, flying low and fairly slowly, often being quite low to ground, i.e. only around 150 cm. More often than visually finding their prey, it is thought that long-eared owls most often audibly detect the rustling of their intended food. In lab settings, long-eared owls were considerably more skilled at finding mice by sound in more or less complete darkness than tawny and barred owls, and in some American experiments even outclassed the auditorily-acute barn owls in this regard. Once prey is spotted, the long-eared owl's flight suddenly stalls, then they quickly drop with talons spread to pounce on prey that is perceived, or especially, that comes out into the open. Habitat may be perhaps even more key than prey numbers to the selection of hunting grounds. Often when prey numbers are more ample in timbered areas nearer the roost or rich marshy areas in the vicinity, the long-eared owls will still often come to more prey-poor areas such as old fields so that they can detect prey on open ground. The footspan of a long-eared owl, including claws, reaches on average 11.3 and 12.5 cm in males and females, respectively, which would be large for a diurnal bird of prey but is quite small for an owl of its size, given the physiological differences in the way different birds of prey tend to kill their prey. While acciptrid raptors tend to kill by stabbing with their talons through vital organs, owls are more likely to constrict their prey to death, so tend to have proportionately larger, more robust feet. In other medium-sized owls, the footspan in tawny owls and barn owls respectively averages 13.4 and 13.2 cm in between the sexes. Prey capture by long-eared owls was studied and compared to tawny owls in a European experiment. The two owl species caught mammals and beetles caught in similar ways but the long-eared owls shied away from flying sparrows and would only capture the sparrows when they perched. Long-eared owls either disregarded or killed but did not eat amphibians, while tawny owls did catch and eat amphibians when they were available. Occasionally the tawny owls would attack fish whilst one long-eared owl caught but did not eat a fish. The European study further revealed that several owls of different species ate bits of plant and did not appear to do so out of food deprivation or hunger.

Taken as whole, the global population of long-eared owls may appear to have a widely varying diet. One study accrued information from 312 studies from around the species' range. In total 478 prey species were found to be described, of which 180 were mammal species, 191 were bird species, 83 were assorted invertebrate species, 15 were reptiles, 7 were amphibians, and reportedly just a couple fish species. This included a total of approximately 813,033 prey items having been reviewed. However, on closer inspection, the long-eared owl generally appears to be something of a dietary specialist. It usually takes primarily, often nearly entirely, small mammals, e.g. rodents, as food in almost every part of its range. Usually a broad picture emerges that between 80 and 99% of the diet consists of mammals, averaging 94% in one estimate for all of Europe. However, in warmer, insular or more urbanized environments, a greater percentage or, rarely, even a majority of the diet can locally be non-mammalian prey. Mean prey sizes have been studied extensively and are almost always fall within a very narrow range. In Europe, the mean estimated prey size overall was 32.2 g. Meanwhile, in North America, mean prey sizes have varied between 30.7 and 37 g in two estimates. In general, throughout their range, the mean size of prey is generally encapsulated between 20 and 50 g, usually well under 40 g, and only in cases where long-eared owls, perhaps through lessened competition, has regular access to prey weighing 60 to 100 g or more, may the mean prey size range uncommonly reach 50 to 60 g. Cases of exceptionally large prey are mentioned where they occur below.

Defense

During daytime, long-eared owls tends to roost in an upright position on a branch, not infrequently close to the trunk, oftentimes within dense foliage. In winter, the long-eared owl often stays close to the same tree or grove of trees. Usually, when approached, the owl freezes with its body stiffly upright, eyes closed to narrow slits and ear tufts erect. This is called the “tall-thin position” and is common to at least a couple dozen species of typical owl. If approached closed, the owls will alternately open and close their eyes, finally lowering ear tufts, fluffing body plumage and flying to another roost. Unlike most owls, which show a tendency towards territorial behavior on a fixed range year-around when possible, long-eared owls in the non-breeding season may form aggregations of owls while roosting. Such groupings may include 6 to 50 owls, with a European record of about 150 owls at a single roost. Even other migratory owls in the temperate zone do not tolerate each other as closely as do long-eared owls, with short-eared owls seemingly only forming aggregations when food supplies are exceptionally high, while social roosting in long-eared owls seems to occur regardless of local prey numbers. Long-eared owls tend to roost in the depths of the "darkest stands of trees" in order to conceal their presence, though they prefer being close to forested edge to allow access to hunting over more open ground. A study in the New Jersey Meadowlands area showed that roosting owls had a strong fidelity for certain trees, particularly conifers such as cedars where the main truck is large obscured from view and a grouping of at least 2-3 closely clumped trees occurs. Roost height in the New Jersey study was at 3 to 15 m or occasionally higher. In New Jersey, different roosts were preferred each year and in the local heavily modified environment, the owls become partially habituated to human activities. However, approach at closer than 3 to 4 m away usually caused them to flush. Departure of owls for nighttime hunting would generally occur between 40 and 49 minutes after sundown. Studies in the Moscow region of wintering roosts were done over 10 years, with 12 communal and 14 solitary roosts found. The communal roosts included up to 16 individuals per winter, with a mean of 9.9. Overall, the average in Moscow per roost site was 2.1 owls. Vole numbers the preceding year were likely the causes of numeric variations in years here while wind and snow avoidance were key in characteristics of roost sites. Extraordinarily large roosts were the norm in a study in Stavropol, Russia, where the general roost area could host from 80 to 150 individuals each winter over 4 years, with 93.7% of the roosts located in coniferous trees. In Milan, Italy, from 2 to 76 long-eared owls were observed per urban roost site. Here, nighttime observation showed that owls individually would depart the roost at peak during the darkest part of nighttime. A majority of the Milan roosting owls did not fly toward urban areas instead flying to suburban fields and forest where prey is more easily encountered. The reason for roosting in aggregations seems to be at least in part to mitigate predation risks.

Migration

Out of roughly 19 regular species of owl in North America and 13 regular species of owl in Europe, the long-eared owl is classed as one of the five in both continents to be truly migratory, moving annually in at least some areas and in some numbers from summer to winter grounds and back whether or not it is an irruptive year. Northern populations are migratory, showing a strong tendency to wander south in autumn. Some normally young bird from central Europe migrate southwest at distances of up to more than 2,000 km. Central European adults are less migratory, at most merely wandering in winter. Long-eared owls that breed Scandinavia generally migrate to nearly anywhere in Europe, from Great Britain to Southeast Europe, though some may disperse as far as north Africa or Asia Minor. In Europe, males and females seem to differ slightly in migratory behaviour. Long-eared owls wintering in Denmark were found to be heavily biased towards females, also there is a bias towards females in winter surveys in other areas such as southern Sweden. At 10 wintering sites in Europe, females were 36% more common than males. The hypothesis posited by those that studied the owls in Denmark is that females face a higher rate of predation by larger birds of prey and may distribute away from Fennoscandia where densities are high of those predators and to areas that show low densities of these predators. Another, non-exclusive, theory is that they may be avoiding areas with deep snow that may inhibit prey capture. Supporting data that male long-eared owls winter further north than females was gathered in southern Norway, where the recovery of dead owls of the species encountered in late fall throughout winter, males were 45% more common than females. On evidence, many of the females that vacate Norway and even Fennoscandia come to winter in Great Britain. Two birds in ringing studies that were recorded in late winter in Germany were observed to return for the summer to central Russia away) and to eastern Russia away). Birds that breed in central Asia have been recorded to winter in a wide variety of locales, including the Egyptian Nile valley, Pakistan, northern India and southern China. In North America, migrants generally sourced from Canada and the Upper Midwest winter almost anywhere in the remaining United States, however they will irruptively migrate as far as Georgia and several areas of Mexico and seldom in Florida. Typically the northern limit of the wintering range fall up to the Okanagan Valley of British Columbia, the southern reaches of the Upper Midwest and central New England. Spring migration was tracked along with northern saw-whet owls as they migrated through Oswego County, New York via mist nets, with the saw-whet considerably outnumbering long-eared owls. Here, migration of long-eared owl was between March 21 and April 14 and, unlike the saw-whets, the long-eared owl migration does not appear to be effected as extensively by weather conditions. Long-eared owls are 19.5% of owls recorded migrating through Cape May Point in fall, with 26.1% of the specimens from the species caught in the mist nets being adults. More than 90% of long-eared owls migrate between mid-October and late November, with the immatures migrating earlier, 52.1% of juveniles having passed through in October whereas only 9.4% of adults migrated in the month. Cape May studies also indicated that 58.87% of long-eared owls were caught in the dark before dawn rather than other times of night. Based on evidence from Cape May, migrating long-eared owls tend to fly higher above the ground than do migrating saw-whet and barn owls but not as high as the short-eared owl, with the latter owl often able to avoid mist nets apparently via its flying height while moving through. Per a study in Idaho, 7 radio-tagged owls actually migrating both north, 75 to 125 km north of their respective nesting sites, and to higher elevations after the breeding season.

The long-eared owl has the peculiar ability to increase populations and then disperse in nearly multi-directional movements during good years for prey numbers. Banding records across North America show highly erratic numbers and movements across the continent of North America with unpredictable peak numbers of migrants in completely different years respectively for the states of Wisconsin, Michigan, New York and New Jersey. Therefore, the species is sometimes considered “nomadic” despite many populations of the species being consistent annual migrants. Similar tendency towards so-called “nomadism” is shared by other widespread raptors semi-specialized to hunting voles over open ground, such as short-eared owls and hen harriers. These erratic movements and peaks and ebbs of northern populations has lent to descriptions of the long-eared owl as “irruptive”, however it generally moves in quite different ways from owls largely endemic to the taiga, which are more traditionally irruptive in that they tend to migrate little or not at all when prey remain ample in their native home range but then move south in mass when prey populations crash. Long-eared owls, unlike these irruptive northern owls, often migrate from the northern areas regardless of conditions. However, like the northern irruptive owls, long-eared owls tend to appear in unprecedented numbers to the south when a peak prey year is followed by a winter during which prey population crashes. In North America, the migratory habits of long-eared owls are strongly mirrored by those of northern saw-whet owls. Study of banding records in Saskatchewan show that the long-eared owl Canadian populations may be considered more truly irruptive species both as a breeder and migrant in that only appears in numbers during peak vole years, with large numbers only in 4 of 44 banding years. During 7 low years, the long-eared owls of Saskatchewan seemed to disappear altogether from much of the province. Peak years also coincided often with snowshoe hare peaks, possibly due to lessened competition and interspecific predation by great horned owls. The phenomena of movements that seem to be nomadic or purportedly irruptive in nature may occur as well in Europe, though given the species' denser population in general there in comparison to North America may result in less noticeable wide variations in numbers. Years with irruptive numbers of long-eared owls have been noted in the British Isles when prey peaks then crashes back in Scandinavia, resulting in much larger numbers of migrant long-eared owls into the islands than normal, as well as concurrently large numbers of short-eared owls and harriers. In southern Finland during a peak prey year followed by a prey crash, a very large number of long-eared owls were detected and were seen to be likely food stressed, as several were foraging actively during daylight despite the extensive nighttime hours during the season.