Snowy owl

Summary

Snowy owl
Temporal range: Pleistocene–Present
[1]
Snowy Owl (240866707).jpeg
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Strigiformes
Family: Strigidae
Genus: Bubo
Species:
B. scandiacus
Binomial name
Bubo scandiacus
Cypron-Range Bubo scandiacus.svg

     Breeding      Non Breeding
Synonyms
  • Strix scandiaca Linnaeus, 1758
  • Strix nyctea Linnaeus, 1758
  • Nyctea scandiaca (Linnaeus, 1758)

The snowy owl (Bubo scandiacus), also known as the polar owl, the white owl and the Arctic owl,[3] is a large, white owl of the true owl family.[4] Snowy owls are native to the Arctic regions of both North America and the Palearctic, breeding mostly on the tundra.[2] It has a number of unique adaptations to its habitat and lifestyle, which are quite distinct from other extant owls.[5] One of the largest species of owl, it is the only owl with largely white plumage.[4] Males tend to be a purer white overall while females tend to more have more extensive flecks of dark brown.[6] Juvenile male snowy owls have dark markings that may appear similar to females until maturity, at which point they typically turn whiter. The composition of brown markings about the wing, although not foolproof, is the most reliable technique to age and sex individual snowy owls.[7]

Most owls sleep during the day and hunt at night, but the snowy owl is often active during the day, especially in the summertime.[5] The snowy owl is both a specialized and generalist hunter. Its breeding efforts and entirely global population are closely tied to the availability of tundra-dwelling lemmings but in the non-breeding season and occasionally during breeding the snowy owl can adapt to almost any available prey, most often other small mammals and northerly water birds (as well as, opportunistically, carrion).[3][6] Snowy owls typically nest on a small rise on the ground of the tundra.[8] The snowy owl lays a very large clutch of eggs, often from about 5 to 11, with the laying and hatching of eggs considerably staggered.[6] Despite the short Arctic summer, the development of the young takes a relatively long time and independence is sought in autumn.[5]

The snowy owl is a nomadic bird, rarely breeding at the same locations or with the same mates on an annual basis and often not breeding at all if prey is unavailable.[6] A largely migratory bird, snowy owls can wander almost anywhere close to the Arctic, sometimes unpredictably irrupting to the south in large numbers.[6][9] Given the difficulty of surveying such an unpredictable bird, there was little in depth knowledge historically about the snowy owl's status. However, recent data suggests the species is declining precipitously.[2][10] Whereas the global population was once estimated at over 200,000 individuals, recent data suggests that there are probably fewer than 100,000 individuals globally and that the number of successful breeding pairs is 28,000 or even considerably less.[2][11] While the causes are not well-understood, numerous, complex environment factors often correlated with global warming are probably at the forefront of the fragility of the snowy owl's existence.[2][6]

Taxonomy

The snowy owl was one of the many bird species originally described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae, where it was given the binomial name Strix scandiaca.[12] The genus name Bubo is Latin for an horned owl and scandiacus is New Latin for of Scandinavia.[13] The former genera name Nyctea is derivation of Greek meaning "night".[3] Linnaeus originally described the different plumages of this owl as separate species, with the male specimens of snowy owls being considered Strix scandiaca and the likely females considered as Strix nyctea.[3][14] Until recently, the snowy owl was regarded as the sole member of a distinct genus, as Nyctea scandiaca, but mtDNA cytochrome b sequence data shows that it is very closely related to the horned owls in the genus Bubo and the species is now thusly often considered inclusive with that genus.[15][16] However, some authorities debate this classification, still preferring Nyctea. Often authorities are motivated to retain the separate genus on the grounds of osteological distinctions.[3][17]

The engraving Snowy Owl, Plate 121 of The Birds of America by John James Audubon. Male (top) and female (bottom).

Genetic testing revealed a reasonably distinct genetic makeup for snowy owls, being about 8% genetically distinct from other Bubo owls, perhaps giving credence to those who count the species as separate under Nyctea.[3][18] However, a fairly recent shared origin in evolutionary history has been illustrated through a combination of genetic study and fossil review and there is little, other than osteology of the tarsometatarsus, to outright distinguish the snowy owl from other modern species like the Eurasian eagle-owl (Bubo bubo).[3][5] Genetic testing has indicated that the snowy owl may have diverged from related species at around 4 million years ago.[3] Furthermore, it has determined that the living species genetically most closely related to the snowy owl is the great horned owl (Bubo virginianus).[3][19] On a broader scale, owls in general have, through genetic materials, been determined to be a highly distinct group, with outwardly similar groups such as Caprimulgiformes revealed to not be at all closely related.[20][21] Within the owl order, typical owls are highly divergent from barn-owls.[4][22] Furthermore, the Bubo genus likely clustered at some point during the evolutionary process with other largish owls, such as Strix, Pulsatrix and Ciccaba, based on broad similarities in their voice, reprodu