Currently, the long-eared owl is considered to include three to four subspecies.

A. o. otus (Linnaeus, 1758)- This is the nominate subspecies and is distributed throughout the species’ range in the Palearctic.
They may be found as far west as the Azores, northwestern Africa, the Iberian Peninsula and the British Isles through as far east as Sakhalin, Japan and northern China.
Some populations of this race may winter as far south as in Egypt, Pakistan, northern India and southern China.
The wing chord of the nominate subspecies may range between 263 and 313 mm (10.4 and 12.3 in) and tail length may be between 132 and 165 mm (5.2 and 6.5 in).
Size appears to increase slightly from west to east, with owls in China being about 4% larger winged than those from Europe.
Despite there being no known published weights for eastern/Chinese long-eared owls, they appear to obtain the largest sizes within the species.
In this subspecies, the facial disc tends to be pale ochraceous tawny, rimmed black with relatively short eyebrows that are marked whitish or absent entirely of markings.
The erectile ear-tufts are prominent, being colored mainly blackish-brown with tawny edges.
The upperparts are ochraceous-tawny, finely peppered with dusky spots and blackish streaks on a grey "veil", while the crown is finely mottled to dusky.
The nape and hindneck bear dusky shaft-streaks with the feather outer webs of the scapulars being whitish, forming a row across the shoulder.
Primaries basally are uniformly ochraceous-tawny, distally barred light and dark, while the secondaries are barred ochraeous and dusky.
The tail is typically tawny with a greyish wash, overlaid with 6-8 very narrow dark brown bars.
The underparts have a base colour of ochre, with the foreneck and upper breast marked with blackish-brown streaks; these becomes paler below and marked with dusky shaft-streaks and narrow cross bars.
The underwing has distinctive barring and dark comma-like markings at the wrist (conspicuously lacking on overlapping Eurasian short-eared owls).
The eyes tend to be yellowish-orange to orange, but occasionally may be chrome yellow.
The cere is brownish-flesh, the bill is grey and the talons are blackish-grey.
In this subspecies, the downy chick is whitish with pink skin, while the mesoptile plumage is fluffy greyish to brownish-white with diffusely barred dusky flight and tail feathers, being similar to adults but with the ear tufts not yet developed.

A. o. canariensis (Madarász, 1901)- This subspecies is endemic to the Canary Islands.
With a wing chord measurement of 257 to 284 mm (10.1 to 11.2 in), this is seemingly the smallest subspecies of the long-eared owl.
This race averages darker than most long-eared owls of the nominate subspecies, bearing heavier and sharper dark markings overall.
Furthermore, the Canary Island long-eared owls tend to have brighter reddish-orange eyes.

A. o. wilsonianus (Lesson, 1830)- This subspecies is opined to include the long-eared owl's entire range in the Americas, distributed from British Columbia south to California, and in the east from Newfoundland to North Carolina, winters partially down as far south in Georgia, Texas, Mexico (and seldom in Florida).
The wing chord typically measures 284 to 305 mm (11.2 to 12.0 in).
In general, American long-eared owls are more vividly marked than many Eurasian populations.
The facial disc is bright rufous, with a strong blackish rim and extensive white about the disc.
The eyes are typically a deep yellow.
Meanwhile, the markings on the underside usually are quite blackish and prominent with distinct cross bars.
At times, a second subspecies (A. o. tuftsi) is considered in western North America, but current data suggests it is weakly differentiated and may compromise clinal variations due to region and habitat, rather than subspecific differences.
Currently, the long-eared owl is considered to include three to four subspecies.
A. o. otus (Linnaeus, 1758)- This is the nominate subspecies and is distributed throughout the species’ range in the Palearctic. They may be found as far west as the Azores, northwestern Africa, the Iberian Peninsula and the British Isles through as far east as Sakhalin, Japan and northern China. Some populations of this race may winter as far south as in Egypt, Pakistan, northern India and southern China. The wing chord of the nominate subspecies may range between 263 and 313 mm (10.4 and 12.3 in) and tail length may be between 132 and 165 mm (5.2 and 6.5 in). Size appears to increase slightly from west to east, with owls in China being about 4% larger winged than those from Europe. Despite there being no known published weights for eastern/Chinese long-eared owls, they appear to obtain the largest sizes within the species. In this subspecies, the facial disc tends to be pale ochraceous tawny, rimmed black with relatively short eyebrows that are marked whitish or absent entirely of markings. The erectile ear-tufts are prominent, being colored mainly blackish-brown with tawny edges. The upperparts are ochraceous-tawny, finely peppered with dusky spots and blackish streaks on a grey "veil", while the crown is finely mottled to dusky. The nape and hindneck bear dusky shaft-streaks with the feather outer webs of the scapulars being whitish, forming a row across the shoulder. Primaries basally are uniformly ochraceous-tawny, distally barred light and dark, while the secondaries are barred ochraeous and dusky. The tail is typically tawny with a greyish wash, overlaid with 6-8 very narrow dark brown bars. The underparts have a base colour of ochre, with the foreneck and upper breast marked with blackish-brown streaks; these becomes paler below and marked with dusky shaft-streaks and narrow cross bars. The underwing has distinctive barring and dark comma-like markings at the wrist (conspicuously lacking on overlapping Eurasian short-eared owls). The eyes tend to be yellowish-orange to orange, but occasionally may be chrome yellow. The cere is brownish-flesh, the bill is grey and the talons are blackish-grey. In this subspecies, the downy chick is whitish with pink skin, while the mesoptile plumage is fluffy greyish to brownish-white with diffusely barred dusky flight and tail feathers, being similar to adults but with the ear tufts not yet developed.
A. o. canariensis (Madarász, 1901)- This subspecies is endemic to the Canary Islands. With a wing chord measurement of 257 to 284 mm (10.1 to 11.2 in), this is seemingly the smallest subspecies of the long-eared owl. This race averages darker than most long-eared owls of the nominate subspecies, bearing heavier and sharper dark markings overall. Furthermore, the Canary Island long-eared owls tend to have brighter reddish-orange eyes.
A. o. wilsonianus (Lesson, 1830)- This subspecies is opined to include the long-eared owl's entire range in the Americas, distributed from British Columbia south to California, and in the east from Newfoundland to North Carolina, winters partially down as far south in Georgia, Texas, Mexico (and seldom in Florida). The wing chord typically measures 284 to 305 mm (11.2 to 12.0 in). In general, American long-eared owls are more vividly marked than many Eurasian populations. The facial disc is bright rufous, with a strong blackish rim and extensive white about the disc. The eyes are typically a deep yellow. Meanwhile, the markings on the underside usually are quite blackish and prominent with distinct cross bars. At times, a second subspecies (A. o. tuftsi) is considered in western North America, but current data suggests it is weakly differentiated and may compromise clinal variations due to region and habitat, rather than subspecific differences.
Long-eared owl