Long-eared owl
The long-eared owl, also known as the northern long-eared owl or, more informally, as the lesser horned owl or cat owl, is a medium-sized species of owl with an extensive breeding range. The genus name, Asio, is Latin for "horned owl", and the specific epithet, otus, is derived from Greek and refers to a small eared owl. The species breeds in many areas through Europe and the Palearctic, as well as in North America. This species is a part of the larger grouping of owls known as typical owls, of the family Strigidae, which contains most extant species of owl.
This owl shows a partiality for semi-open habitats, particularly woodland edge, as they prefer to roost and nest within dense stands of wood but prefer to hunt over open ground. The long-eared owl is a specialized predator, focusing its diet on small rodents, especially voles, which compose most of their diet. Under some circumstances, such as population cycles of their regular prey, arid or insular regional habitats or urbanization, this species can adapt fairly well to a diversity of prey, including birds and insects. The long-eared owl utilizes nests built by other animals, in particular by corvids. Breeding success in this species is correlated with prey populations and predation risks. Unlike many owls, long-eared owls are not strongly territorial or sedentary. They are partially migratory and sometimes characterized as "nomadic". Another characteristic of this species is its partiality for regular roosts shared by a number of long-eared owls at once. The long-eared owl is one of the most widely distributed and most numerous owl species in the world, and due to its very broad range and numbers it is considered a least concern species by the IUCN. Nonetheless, strong declines have been detected for this owl in several parts of its range.
Taxonomy
The long-eared owl was described by Linnaeus in 1758 in the tenth edition of Systema Naturae under the binomial name Strix otus. It is now assigned to the genus Asio that was introduced by Mathurin Jacques Brisson in 1760.There are eight known species worldwide in the genus Asio, also referred to as eared owls. Despite similarities and being considered as in the same genus, it was found in a study utilizing electrophoresis that the genetic distance between long-eared owls and short-eared owls was unusually large for species within the same genera. Notwithstanding fossil records of Asio species showing their presence during prehistory in locations like Kansas and Idaho and California, the exact area of evolutionary origin of the long-eared owl is unknown and unlikely to ever be known. At least three modern species represent related derivations, possibly with long-eared owls as the paraspecies or as part of a species complex that potentially bears a basal common ancestor. In all three cases, the related owls are obviously more tropical in distribution and adapted to more humid conditions, with darker plumage, and larger bodies with apparently stronger feet and more overdeveloped talons, possibly exploiting a relatively unoccupied ecological niche against competing owls. One of these three is the Stygian owl, which is the darkest derivation of all and readily known to be distinct for some time. The other two slightly larger, tropical species, possibly housed in a species complex with the long-eared owl, were at one time considered to be part of the long-eared owl species. One of these is the Madagascar owl, obviously endemic to the island of its name, while the other is the Abyssinian owl, native to east Africa, especially in the northern area such as Ethiopia. While the marsh owl of Africa is outwardly very similar to and likely closely related to the short-eared owl, the striped owl is somewhat of an outlier among living Asio species and of mysterious origin. Despite being genetically related to the other living Asio species, it does not appear to be a close cousin. Studies of the mitochondrial genome found that the Asio genus, and consequently the long-eared owl, diverged most recently among living owl groups from the Otus or scops owl genus, with a more distant branch division from the Strix genus. A study of the genetic homogeny of long-eared owls in a single roost site was shown to be slightly higher than between different roosts. However, this homogeny is relatively low for a communal roosting bird in general.
Subspecies
Four subspecies of the long-eared owl are recognised:- A. o. otus – This is the nominate subspecies and is distributed throughout the species' range in the Palearctic. It 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 Egypt, Pakistan, northern India and southern China. The wing chord of the nominate subspecies ranges between and the tail length may be between. 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 ochraceous 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 become 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. 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 – This subspecies is endemic to the Canary Islands. With a wing chord measurement of, 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 – This subspecies is found in south-central and southeastern Canada to southern USA. The wing chord typically measures. 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.
- A. o. tuftsi Godfrey, 1948 – The range is from western Canada to south-central USA. It differs from A. o. wilsonianus in having paler plumage. The brown mottling on upper parts is paler and more restricted. It is weakly differentiated and may comprise clinal variations due to region and habitat, rather than subspecific differences.
Description
In general coloration, the long-eared owl is a hue of ochraceous-tawny with a grayish or brownish wash variably manifesting. The base color is overlaid with variable blackish vertical streaks, which are more apparent about the wings and back. The scapulars are 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 an 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, densely washed above as to appear largely dusky brown on the back and the underside overlaid with bolder dusky-blackish marks. Meanwhile, in some desert-like regions, the plumage tends towards a washed out look, at times appearing cream or yellowish, with sparser and lighter dusky markings overall. The facial disc is 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 tawny on the back. Long-eared owl possess a blackish bill while its eyes vary from yellowish-orange to orange-red. Tarsi and toes are feathered.
The long-eared owl is a medium-sized owl, which measures between in total length. Their wingspan is relatively large for their size, measuring. Compared to other widespread owls 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 lighter and slenderer bodied, with mature weights around half of those of tawny owls being common. As expected in owls and birds of prey in general, long-eared owls display reverse sexual dimorphism in which females are usually larger than males. Males furthermore may be paler in plumage than females. In Finland, one survey of the body mass of mature birds found that 22 males averaged while 20 females averaged. 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 and 24 females averaged, intermediate in Denmark and heaviest in the Netherlands, where 21 males averaged and 24 females averaged. In migratory owls largely from Scandinavian summer grounds in England, the average weight of 8 males was and the average of 28 females was. Meanwhile, in various studies in North America, 38 males were found to average, 55 males to average and 15 males . From the same studies, respectively, 28 females averaged, 49 females averaged and 19 females averaged. Museum specimens in North America were found to average in 38 males and in 28 females, while 520 migrating adults in Duluth, Minnesota averaged. In all, long-eared owl males may vary in weight from while females may vary from.
In standard measurements, long-eared owls vary in wing chord length from in males, with 883 in North America averaging, and in females, with 520 American ones averaging. The tail may measure in males and in females, with 1,408 owls averaging. Less widely measured are bill length, which averaged in males and in females from North America, and tarsus length, which averaged in 20 males and for 16 females from Europe, with a range in both sexes of. In terms of their skeletal structure, it bears a relatively wide skull but small eyes and orbits, while the beak is elongated but weak. The legs are long and thin and, while needle-sharp, the talons are relatively fine and the feet weak for an owl. However, the talons are still proficient at drawing blood if contact is made with human skin.