The snowy owl (''Bubo scandiacus''), also known as the polar owl, the white owl and the Arctic owl,
is a large, white
owl of the
true owl
The true owls or typical owls (family (biology), family Strigidae) are one of the two generally accepted families of owls, the other being the barn owls and bay owls (Tytonidae). This large family comprises 230 living or recently extinct species ...
family.
Snowy owls are native to the
Arctic
The Arctic (; . ) is the polar regions of Earth, polar region of Earth that surrounds the North Pole, lying within the Arctic Circle. The Arctic region, from the IERS Reference Meridian travelling east, consists of parts of northern Norway ( ...
regions of both North America and the
Palearctic
The Palearctic or Palaearctic is a biogeographic realm of the Earth, the largest of eight. Confined almost entirely to the Eastern Hemisphere, it stretches across Europe and Asia, north of the foothills of the Himalayas, and North Africa.
Th ...
, breeding mostly on the
tundra
In physical geography, a tundra () is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. There are three regions and associated types of tundra: #Arctic, Arctic, Alpine tundra, Alpine, and #Antarctic ...
.
[ It has a number of unique adaptations to its habitat and lifestyle, which are quite distinct from other extant owls.] One of the largest species of owl, it is the only owl with mainly white plumage.[ Males tend to be a purer white overall while females tend to have more extensive flecks of dark brown.] Juvenile male snowy owls have dark markings and 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 for aging and sexing individual snowy owls.
Most owls sleep during the day and hunt at night, but the snowy owl is often active during the day, especially in the summertime.[ The snowy owl is both a specialized and generalist hunter. Its breeding efforts and global population are closely tied to the availability of tundra-dwelling ]lemming
A lemming is a small rodent, usually found in or near the Arctic in tundra biomes. Lemmings form the subfamily Arvicolinae (also known as Microtinae) together with voles and muskrats, which form part of the superfamily Muroidea, which also inclu ...
s, but in the non-breeding season, and occasionally during breeding, the snowy owl can adapt to almost any available prey – most often other small mammal
A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...
s and northerly water bird
A water bird, alternatively waterbird or aquatic bird, is a bird that lives on or around water. In some definitions, the term ''water bird'' is especially applied to birds in freshwater ecosystems, although others make no distinction from seabi ...
s, as well as, opportunistically, carrion
Carrion (), also known as a carcass, is the decaying flesh of dead animals.
Overview
Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures ...
.[ Snowy owls typically nest on a small rise on the ground of the tundra.][Hume, R. (1991). ''Owls of the world''. Running Press, Philadelphia.] The snowy owl lays a very large clutch of egg
An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the ...
s, often from about 5 to 11, with the laying and hatching of eggs considerably staggered.[ Despite the short Arctic summer, the development of the young takes a relatively long time and independence is sought in autumn.][
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.][ A largely migratory bird, snowy owls can wander almost anywhere close to the Arctic, sometimes unpredictably irrupting to the south in large numbers.] 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.[Bent, A. C. (1938). ''Life Histories of North American Birds of Prey (part 2), Orders Falconiformes and Stringiformes (Vol. 170)''. US Government Printing Office.] 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. While the causes are not well understood, numerous, complex environmental factors often correlated with global warming
Present-day climate change includes both global warming—the ongoing increase in global average temperature—and its wider effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes ...
are probably at the forefront of the fragility of the snowy owl's existence.[
]
Taxonomy
The snowy owl was one of the many bird species originally described by Carl Linnaeus
Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...
in his landmark 1758 10th edition of ''Systema Naturae'', where it was given the binomial name ''Strix scandiaca''. The genus name ''Bubo'' is Latin
Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
for " horned owl" and ''scandiacus'' is Neo-Latin
Neo-LatinSidwell, Keith ''Classical Latin-Medieval Latin-Neo Latin'' in ; others, throughout. (also known as New Latin and Modern Latin) is the style of written Latin used in original literary, scholarly, and scientific works, first in Italy d ...
for "of Scandinavia
Scandinavia is a subregion#Europe, subregion of northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. ''Scandinavia'' most commonly refers to Denmark, Norway, and Sweden. It can sometimes also ...
". The former generic name ''Nyctea'' is derived from Greek meaning "night".[ 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''.][ Until recently, the snowy owl was regarded as the sole member of a distinct ]genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
, as ''Nyctea scandiaca'', but mtDNA
Mitochondrial DNA (mtDNA and mDNA) is the DNA located in the mitochondria organelles in a eukaryotic cell that converts chemical energy from food into adenosine triphosphate (ATP). Mitochondrial DNA is a small portion of the DNA contained in ...
cytochrome ''b'' sequence
In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed and order matters. Like a set, it contains members (also called ''elements'', or ''terms''). The number of elements (possibly infinite) is cal ...
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.[Wink, M. & Heidrich, P. (2000). "Molecular systematics of owls (Strigiformes) based on DNA-sequences of the mitochondrial cytochrome b gene", pp. 819–828 in: Chancellor, R.D. & Meyburg, B.U. eds. (2000). ''Raptors at Risk. Proceedings of the V World Conference on Birds of Prey and Owls''. Midrand, Johannesburg, 4–11 August 1998. WWGBP & Hancock House, Berlin & Blaine, Washington.] However, some authorities debate this classification, still preferring ''Nyctea''. Often authorities are motivated to retain the separate genus on the grounds of osteological distinctions.[Ford, N. L. (1967). ''A systematic study of the owls based on comparative osteology''. PhD diss, Univ. of Michigan, Ann Arbor.]
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''.[ 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
The tarsometatarsus is a bone that is only found in the lower leg of birds and some non-avian dinosaurs. It is formed from the fusion of several bird bones found in other types of animals, and homologous to the mammalian tarsus (ankle bones) a ...
, to outright distinguish the snowy owl from other modern species like the Eurasian eagle-owl
The Eurasian eagle-owl (''Bubo bubo'') is a species of eagle-owl, a type of bird that resides in much of Eurasia. It is often just called the eagle-owl in Europe and Asia.
It is one of the largest species of owl. Females can grow to a total le ...
(''Bubo bubo'').[ Genetic testing has indicated that the snowy owl may have diverged from related species at around 4 million years ago.][ Furthermore, it has determined that the living species genetically most closely related to the snowy owl is the ]great horned owl
The great horned owl (''Bubo virginianus''), also known as the tiger owl (originally derived from early naturalists' description as the "winged tiger" or "tiger of the air") or the hoot owl, is a large owl native to the Americas. It is an extreme ...
(''Bubo virginianus''). 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. Within the owl order, typical owls are highly divergent from barn-owl
The barn owls, owls in the genus ''Tyto'', are the most Cosmopolitan distribution, widely distributed genus of owls in the world. They are medium-sized owls with large heads and characteristic heart-shaped faces. They have long, strong legs with ...
s.[ 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, reproductive behaviors (i.e. hooting postures) and a similar number and structure of ]chromosome
A chromosome is a package of DNA containing part or all of the genetic material of an organism. In most chromosomes, the very long thin DNA fibers are coated with nucleosome-forming packaging proteins; in eukaryotic cells, the most import ...
s and autosome
An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosomal (sex chromosome) pairs, which may have different structures. The DNA in autosomes ...
s.[ A number, but not all, of extant typical owls seem to have evolved from an ancient shared ]common ancestor
Common descent is a concept in evolutionary biology applicable when one species is the ancestor of two or more species later in time. According to modern evolutionary biology, all living beings could be descendants of a unique ancestor commonl ...
with the ''Bubo'' owls. In addition to the question of relationship of the traditional ''Bubo'' owls to the snowy owls, ongoing ambiguity of the relationship of other similarly large-sized owls has been persistent. These have sometimes either been included in the genus or within separate genera, i.e. the '' Ketupu'' or fish owls and the ''Scotopelia
Fishing owls form the genus, ''Scotopelia'', of sub-Saharan African birds in the family true owl, Strigidae, the true owls. The genus is closely related to the genus ''Ketupa'', and may be embedded within it.
The genus contains three species:
...
'' or fishing owls. Despite the adaptive distinctions, the grouping of these large owls (i.e. ''Bubo'', snowy, fish and perhaps fishing owls) appears to be borne out via research of karyotype
A karyotype is the general appearance of the complete set of chromosomes in the cells of a species or in an individual organism, mainly including their sizes, numbers, and shapes. Karyotyping is the process by which a karyotype is discerned by de ...
s.[''Owls of the World: A Photographic Guide'' by Mikkola, H. Firefly Books (2012), ]
The fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...
history of snowy owls is fairly well documented despite some early confusion on how to distinguish the skeletal structure of the snowy owls from eagle-owls. It was determined that the snowy owl once was distributed much more widely and far farther to the south during the Quaternary glaciation
The Quaternary glaciation, also known as the Pleistocene glaciation, is an alternating series of glacial period, glacial and interglacial, interglacial periods during the Quaternary period that began 2.58 Year#SI prefix multipliers, Ma (million ...
when much of the Northern Hemisphere
The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...
was in the midst of an ice age
An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages, and g ...
.[ Fossil records shows that snowy owls once could be found in Austria, Azerbaijan, ]Czechoslovakia
Czechoslovakia ( ; Czech language, Czech and , ''Česko-Slovensko'') was a landlocked country in Central Europe, created in 1918, when it declared its independence from Austria-Hungary. In 1938, after the Munich Agreement, the Sudetenland beca ...
, England, France, Germany, Hungary, Italy, Poland, Sardinia and Spain as well as in the Americas in Cape Prince of Wales, Little Kiska Island, St. Lawrence Island, and in Illinois
Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. It borders on Lake Michigan to its northeast, the Mississippi River to its west, and the Wabash River, Wabash and Ohio River, Ohio rivers to its ...
.[ In the ]Late Pleistocene
The Late Pleistocene is an unofficial Age (geology), age in the international geologic timescale in chronostratigraphy, also known as the Upper Pleistocene from a Stratigraphy, stratigraphic perspective. It is intended to be the fourth division ...
the range expanded southward even more so to Bulgaria (80,000–16,000 years, Kozarnika Cave, W Bulgaria). and much of the Italian Peninsula. Pleistocene
The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
era fossils from France, i.e. ''B. s. gallica'', showed that the snowy owls of the time were somewhat bulkier (though still notably smaller than contemporary eagle-owls of the times, which were larger than the eagle-owls of today) and osteologically more sexually dimorphic in size than the modern form (9.9% dimorphism in favor of females in the fossils against 4.8% in the same features today). There are no subspecific or other geographical variations reported in the modern snowy owls, with individuals of vastly different origins breeding together readily due to their nomadic habits.[ Despite apparent variations in body size, environmental conditions are the likely variant rather than genetics.][ No evidence could be found of phylogeographic variation in snowy owls upon testing. Furthermore, the snowy owl appears to have a similar level of ]genetic diversity
Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It ranges widely, from the number of species to differences within species, and can be correlated to the span of survival for a species. It is d ...
as other European owls.[
]
Hybrids
Snowy owls are not known to interbreed with other owl species in the wild, and accordingly, no hybrids of snowy owls and other owl species have yet been sighted in the wild. However, a hobby falconer in Kollnburg, Germany, bred hybrids from a male snowy owl and a female Eurasian eagle-owl (''Bubo bubo'') in 2013.["Schnuhu": Überraschende Kreuzung – Ich bin Bayerns süßester Fratz!](_blank)
tz.de Retrieved on 7 October 2016 The two resulting male hybrid owls possessed the prominent ear-tufts (generally absent in snowy owls), general size, orange eyes, and the same pattern of black markings on their plumage from their Eurasian eagle-owl mother, while retaining the generally black-and-white plumage colours from their snowy owl father. The hybrids were dubbed "''Schnuhus''" from the German words for snowy owl and Eurasian eagle-owl (''Schnee-Eule'' and ''Uhu'', respectively). As of 2014, the hybrids had grown to maturity and were healthy.
Description
The snowy owl is mostly white. They are purer white than predatory mammals such as polar bear
The polar bear (''Ursus maritimus'') is a large bear native to the Arctic and nearby areas. It is closely related to the brown bear, and the two species can Hybrid (biology), interbreed. The polar bear is the largest extant species of bear ...
s (''Ursus maritimus'') and Arctic fox
The Arctic fox (''Vulpes lagopus''), also known as the white fox, polar fox, or snow fox, is a small species of fox native to the Arctic regions of the Northern Hemisphere and common throughout the Tundra#Arctic tundra, Arctic tundra biome. I ...
(''Vulpes lagopus'').[ Often when seen in the field, these owls can resemble a pale rock or a lump of snow on the ground.][ They usually appear to lack ear tufts but very short (and probably vestigial) tufts can be erected in some situations, perhaps most frequently by the female when she is sitting on the nest.][ The ear tufts measure about and consist of about 10 small feathers.][ The snowy owl has bright yellow eyes.][ The head is relatively small and, even for the relatively simply adapted hearing mechanism of a ''Bubo'' owl, the facial disc is shallow and the ear is uncomplicated.][ 1 male had ear slits of merely on left and on the right.][
Females are almost invariably more duskily patterned than like-age males.][ In mature males, the upper parts are plain white with usually a few dark spots on the miniature ear-tufts, about the head and the tips of some primaries and secondaries whilst the underside is often pure white.][ Despite their reputation for being purely white, only 3 out of 129 Russian museum specimens of adult males showed an almost complete absence of darker spots. The adult female is usually considerably more spotted and often slightly barred with dark brown on the crown and the underparts. Her flight and tail feathers are faintly barred brown whilst the underparts are white in base color with brown spotting and barring on the flanks and upper breast.][ In confusingly plumaged snowy owls, the sex can be determined by the shape of wing markings, which manifest as bars more so in females and spots in males.] However, the very darkest males and the lightest females are nearly indistinguishable by plumage.[
On rare occasions, a female can appear almost pure white, as has been recorded in both the field and in captivity.][McMorris, A. (2011). ''Snowy Owls: Age, Sex and Plumage''. Presentation Delaware Valley Ornithological Club.] There is some evidence that some of the species grow paler with age after maturity.[Dementiev, G. P., Gladkov, N. A., Ptushenko, E. S., Spangenberg, E. P., & Sudilovskaya, A. M. (1966). ''Birds of the Soviet Union, vol. 1''. Israel Program for Scientific Translations, Jerusalem.] One study's conclusions were that males were usually but not always lighter and that correctly aging is extremely difficult, sometimes individuals either get lighter, darker or do not change their appearance with age.[ On the other hand, with close study, it is possible to visually identify even individual snowy owls using the pattern of markings on the wing, which can be somewhat unique in each individual. After a fresh moult, some adult females that previously appeared relatively pale newly evidenced dark, heavy markings. On the contrary, some banded individuals over at least four years were observed to have been almost entirely unchanged in the extent of their markings.][ In another very pale owl, the ]barn owl
The barn owls, owls in the genus '' Tyto'', are the most widely distributed genus of owls in the world. They are medium-sized owls with large heads and characteristic heart-shaped faces. They have long, strong legs with powerful talons. The ter ...
(''Tyto alba''), the sexual dimorphism of spotting appears to be driven by genetics while, in snowy owls, environment may be the dictating factor instead.[
The chicks are initially grayish white but quickly transition to dark gray-brown in the mesoptile plumage. This type of plumage ]camouflage
Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...
s effectively against the variously colored lichen
A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...
s that dot the tundra ground.[ This is gradually replaced by plumage showing dark barring on white. At the point of fledging, the plumage often becomes irregularly mottled or blotched with dark and is mostly solidly dark gray-brown above with white eyebrows and other areas of the face white.][ Recently fledged young can already be sexed to a semi-reliable degree by the dark marking patterns about their wings.] The juvenile plumage resembles that of adult females but averages slightly darker on average.[ By their second moult fewer or more broken bars are usually evidenced on the wing. The extent of white and composition of wing patterns become more dimorphic by sex with each juvenile moult, culminating in the 4th or 5th pre-basic moult, wherein the owls are hard to distinguish from mature adults.][
Moults usually occur from July and September, non-breeding birds moulting later and more extensively, and are never extensive enough to render the owls flightless.][ Evidence indicates that snowy owls may attain adult plumage at 3 to 4 years of age, but fragmentary information suggests that some males are not fully mature and/or as fully white in plumage that they can attain until the 9th or 10th year.] Generally speaking, moults of snowy owls occur more quickly than do those of Eurasian eagle-owls.[
The toes of the snowy owl are extremely thickly feathered white, while the claws are black.][ The toe feathers are the longest known of any owl, averaging at , against the great horned owl which has the 2nd longest toe feathers at a mean of ][ Occasionally, snowy owls may show a faint blackish edge to the eyes and have a dark gray cere, though this is often not visible from the feather coverage, and a black bill.][ Unlike many other whitish birds, the snowy owl does not possess black wingtips, which is theorized to minimize wear-and-tear on the wing feathers in the other whitish bird types. The conspicuously notched primaries of the snowy owl appear to give an advantage over similar owls in long-distance flight and more extensive flapping flight.
The snowy owl does have some of the noise-canceling serrations and comb-like wing feathers that render the flight of most owls functionally silent, but they have fewer than most related ''Bubo'' owls. Therefore, in combination with its less soft feathers, the flight of a snowy owl can be somewhat audible at close range.][ The flight of snowy owls tends to be steady and direct and is reminiscent to some of the flight of a large, slow-flying falcon.][ Though capable of occasional ]gliding flight
Gliding flight is heavier-than-air flight without the use of thrust; the term volplaning also refers to this mode of flight in animals. It is employed by flying and gliding animals, gliding animals and by aircraft such as glider (aircraft), gl ...
, there is no evidence that snowy owls will soar. It is said that the species seldom exceeds a flying height of around even during passage.[ While the feet are sometimes described as "enormous", the tarsus is in osteological terms relatively short at 68% the length of those of a Eurasian eagle-owl but the claws are nearly as large, at 89% of the size of those of the eagle-owl.][
Despite its relatively short length, the tarsus is of similar circumference as in other ''Bubo'' owls. Also compared to an eagle-owl, the snowy owl has a relatively short decurved ]rostrum
Rostrum may refer to:
* Any kind of a platform for a speaker:
**dais
**pulpit
** podium
* Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects
* Rostrum (ship), a form of bow on naval ...
, a proportionately greater length to the interorbital roof and a much longer sclerotic ring surrounding the eyes while the anterior opening are the greatest known in any owl.[ Owls have extremely large eyes which are nearly the same size in large species such as the snowy owl as those of humans.
The snowy owl's eye, at about in diameter, is slightly smaller than those of great horned and Eurasian eagle-owls but is slightly larger than those of some other large owls.][ Snowy owls must be able to see from great distances and in highly variable conditions but probably possess less acute night vision than many other owls.][ Based on the study of ]dioptre
A dioptre ( British spelling) or (American spelling), symbol dpt or D, is a unit of measurement with dimension of reciprocal length, equivalent to one reciprocal metre, . It is normally used to express the optical power of a lens or curved mi ...
s in different owl species, the snowy owl was determined to have eyesight better suited to long-range perception than to close discrimination, while some related species such as great horned owls could probably more successful perceive closer objects. Despite their visual limits, snowy owls may have up to 1.5 times more visual acuity than humans.[ Like other owls, snowy owls can probably perceive all colors but cannot perceive ]ultraviolet
Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...
visual pigments. Owls have the largest brains of any bird (increasing in sync with the size of the owl species), with the size of the brain and eye related less to intelligence
Intelligence has been defined in many ways: the capacity for abstraction, logic, understanding, self-awareness, learning, emotional knowledge, reasoning, planning, creativity, critical thinking, and problem-solving. It can be described as t ...
than perhaps to increased nocturnality and predatory behavior.
Size
The snowy owl is a very large owl.[ They are the largest avian predator of the High Arctic and one of the largest owls in the world.][ Snowy owls are about the sixth or seventh heaviest living owl on average, around the fifth longest and perhaps the third longest winged.][Weidensaul, S. (2015). ''Owls of North America and the Caribbean''. Houghton Mifflin Harcourt.] This species is the heaviest and longest winged owl (as well as the second longest) in North America, the second heaviest and longest winged owl in Europe (and third longest) but is outsized in bulk by 3 or 4 other species in Asia.[ Despite being sometimes described as of similar size, the snowy owl is somewhat larger in all aspects of average size than the ]great horned owl
The great horned owl (''Bubo virginianus''), also known as the tiger owl (originally derived from early naturalists' description as the "winged tiger" or "tiger of the air") or the hoot owl, is a large owl native to the Americas. It is an extreme ...
while the similarly specialized taiga
Taiga or tayga ( ; , ), also known as boreal forest or snow forest, is a biome characterized by coniferous forests consisting mostly of pines, spruces, and larches. The taiga, or boreal forest, is the world's largest land biome. In North A ...
-dwelling great grey owl (''Strix nebulosa''), is longer in total length and of similar dimensions in standard measurements, but is shorter winged and much less heavy than the snowy owl.[
In Eurasia, the ]Eurasian eagle-owl
The Eurasian eagle-owl (''Bubo bubo'') is a species of eagle-owl, a type of bird that resides in much of Eurasia. It is often just called the eagle-owl in Europe and Asia.
It is one of the largest species of owl. Females can grow to a total le ...
is larger in all standards of measurements than the snowy owl not to mention two additional species each from Africa and Asia that are slightly to considerably heavier on average than the snowy owl.[ Like most ]birds of prey
Birds of prey or predatory birds, also known as (although not the same as) raptors, are hypercarnivorous bird species that actively predation, hunt and feed on other vertebrates (mainly mammals, reptiles and smaller birds). In addition to speed ...
, the snowy owl shows reverse sexual dimorphism relative to most non-raptorial birds in that females are larger than males.[ Sexual dimorphism that favors the female may have some correlation with being able to more effectively withstand food shortages such as during brooding as well as the rigors associated with incubating and brooding. Females are sometimes described as “giant” whereas males appear relatively “neat and compact”.][ However, the sexual dimorphism is relatively less pronounced compared to some other ''Bubo'' species.]
Male snowy owls have been known to measure from in total length, with an average from four large samples of and a maximum length, perhaps in need of verification, of reportedly .[Eckert, A. W. (1987). ''The Owls of North America, North of Mexico: All the Species and Subspecies Illustrated in Color and Fully Described''. Gramercy.][Parmelee, D. F. (1972). ''Canada's incredible arctic owls''. Beaver no. summer:30–41.][Priklonskiy, S.G. (1993). ''Snowy Owl — Nyctea scandiaca (Linnaeus, 1758)''. In: ''Birds of Russia and adjoining regions: Pterocliformes, Columbiformes, Cuculiformes, Strigiformes''. Moscow, p. 258–270. (in Russian).] In wingspan, males may range from , with a mean of .[ In females, total length has been known to range from , with a mean of and an unverified maximum length of perhaps (if so they would have the second longest maximum length of any living owl, after only the great grey owl).][
Female wingspans have reportedly measured from , with a mean of .][ Despite one study claiming that snowy owl had the highest ]wing loading
In aerodynamics, wing loading is the total weight of an aircraft or flying animal divided by the area of its wing. The stalling speed, takeoff speed and landing speed of an aircraft are partly determined by its wing loading.
The faster an airc ...
(i.e. grams per square cm of wing area) of any of 15 well-known owl species, more extensive sampling demonstratively illustrated that the wing loading of snowy owls is notably lower than Eurasian eagle- and great horned owls.[ The conspicuously long-winged profile of a flying snowy owl compared to these related species may cause some to compare their flight profile to a bulkier version of an enormous '' Buteo'' or a large ]falcon
Falcons () are birds of prey in the genus ''Falco'', which includes about 40 species. Some small species of falcons with long, narrow wings are called hobbies, and some that hover while hunting are called kestrels. Falcons are widely distrib ...
.[ Body mass in males can average from , with a median of and a full weight range of from six sources.] Body mass in females can average from , with a median of and a full weight range of .[ Larger than the aforementioned body mass studies, a massive pooled dataset at six wintering sites in North America showed that 995 males averaged at while 1,189 females were found to average .] Reported weights of down to for males and of for females are probably in reference to owls in a state of starvation
Starvation is a severe deficiency in caloric energy intake, below the level needed to maintain an organism's life. It is the most extreme form of malnutrition. In humans, prolonged starvation can cause permanent organ damage and eventually, de ...
. Such emaciated individuals are known to highly impaired and starvation deaths are probably not infrequent in winters with poor food accesses.[
Standard measurements have been even more widely reported than length and wingspan.][ The wing chord of males can vary from , averaging from with a median of .] The wing chord of females can vary from , averaging from with a median of .[ The ]tail
The tail is the elongated section at the rear end of a bilaterian animal's body; in general, the term refers to a distinct, flexible appendage extending backwards from the midline of the torso. In vertebrate animals that evolution, evolved to los ...
length of males can vary on average from , with a full range of and a median of .[ The tail length of females can average from , with a full range of and a median of .][
Data indicates that slightly longer wing chord and tail lengths were reported on average in Russian data than in American research, however the weights were not significantly different in the two regions.][ Less widely taken measurements include the culmen, which can measure from with a median average of in males and in females, and the total bill length which is from , with an average in both sexes of .][ Tarsal length in males averages about , with a range of , and averages about , with a range of , in females.][
]
Identification
The snowy owl is certainly one of the most unmistakable owls (or perhaps even animals) in the world.[ No other species attains the signature white stippled sparsely with black-brown color of these birds, a coloring which renders their bright yellow eyes all the more detectable, nor possesses their obvious extremely long feathering.][ The only other owl to breed in the High Arctic is the ]short-eared owl
The short-eared owl (''Asio flammeus'') is a widespread grassland species in the family Strigidae. Owls belonging to genus ''Asio'' are known as the eared owls, as they have tufts of feathers resembling mammalian ears. These "ear" tufts may or ...
(''Asio flammeus''). Both species inhabit open country, overlap in range and are often seen by day, but the short-eared is much smaller and more tan or straw-colored in coloration, with streaked brown on chest. Even the palest short-eared owls conspicuously differ and are darker than the snowy owl; additionally the short-eared most often hunts in extended flights.[Pyle, P. (1997). ''Identification Guide to North American Birds, Part I: Columbidae to Ploceidae''. Slate Creek Press, Bolinas, CA, USA.]
More similar owls such as the Eurasian eagle-owl
The Eurasian eagle-owl (''Bubo bubo'') is a species of eagle-owl, a type of bird that resides in much of Eurasia. It is often just called the eagle-owl in Europe and Asia.
It is one of the largest species of owl. Females can grow to a total le ...
and the great horned owl
The great horned owl (''Bubo virginianus''), also known as the tiger owl (originally derived from early naturalists' description as the "winged tiger" or "tiger of the air") or the hoot owl, is a large owl native to the Americas. It is an extreme ...
attain a fairly pale, sometimes white-washed look in their northernmost races. These species do not normally breed nearly as far north as snowy owls but overlaps certainly do occur with snowy owls when the latter owl sometimes comes south in winter. However, even the most pale great horned and Eurasian eagle-owls are still considerably more heavily marked with darker base colors than snowy owls (the whitest eagle-owls are paler than the whitest great horned owls), possess much larger and more conspicuous ear tufts and lack the bicolored appearance of the darkest snowy owls. While the great horned owl has yellow eyes like the snowy owl, the Eurasian eagle-owl tends to have bright orange eyes. The open terrain
Open terrain, open country or open ground is terrain which is mostly flat and free of obstructions such as trees and buildings. Examples include farmland, grassland and specially cleared areas such as an airport.
Such terrain is significant in ...
habitats normally used by wintering snowy owls are also distinct from the typical edge and rocky habitats usually favored by the great horned and Eurasian eagle-owls, respectively.
Vocalizations
The snowy owl differ in their calls from other ''Bubo'' owls, with a much more barking quality to their version of a hooting song.[ Perhaps as many as 15 different calls by mature snowy owls have been documented.] The main vocalization is a monotonous sequence that normally contains 2–6 (but occasionally more), rough notes similar to the rhythm of a barking dog: ''krooh krooh krooh krooh''...[ The call may end with an emphatic ''aaoow'', which is somewhat reminiscent of the deep alarm call of a ]great black-backed gull
The great black-backed gull (''Larus marinus'') is the largest member of the gull family. It is a very aggressive hunter, pirate, and scavenger which breeds on the coasts and islands of the North Atlantic in northern Europe and northeastern Nort ...
(''Larus marinus'').[ They will call mainly from a perch but also sometimes do so in flight.][ The ''krooh'' call of the male snowy owl may perform multiple functions such as competitive exclusion of other males and advertising to females.]
The calls of this species may carry exceptionally far in the thin air of Arctic, certainly over more than , and maybe even to as much away.[ The female has a similar call to male but can be higher-pitched and/or more guttural as well as single notes which are often disyllabic, ''khuso''.][ Female snowy owls have also been known to utter chirps and high screaming notes, similar to those of the nestlings.][ Both sexes may at times give a series of clucking, squeals, grunts, hisses and cackles, perhaps such as in circumstances when they are excited.] The alarm call is a loud, grating, hoarse ''keeea''.[
Another raspier bark is recorded, sometimes called a "watchman's rattle" call, and may be transcribed as ''rick, rick, rick'', ''ha, how, quack, quock'' or ''kre, kre, kre, kre, kre''.][ A female attacking to protect her nest was recorded to let out a crowed ''ca-ca-oh'' call, whilst other owls attacking to protect the nest did a loud version of the typical call while circling before dropping down.] They may also clap their beak in response to threats or annoyances. While called clapping, it is believed this sound may actually be a clicking of the tongue, not the beak.
Though largely only vocal in the breeding season, leading to some erroneous older accounts describing the snowy owl as completely silent, some vocalizations have been recorded in winter in the northern United States.[ Initially, the young of the snowy owl have a high pitched and soft begging call which develops into a strong, wheezy scream at around 2 weeks. At the point when the young owls leave the nest around 3 weeks, the shrill squeals they emit may allow the mothers to locate them.][
]
Distribution and habitat
Breeding range
The snowy owl is typically found in the northern circumpolar region, where it makes its summer home north of latitude 60° north though sometimes down to 55 degrees north.[ However, it is a particularly ]nomad
Nomads are communities without fixed habitation who regularly move to and from areas. Such groups include hunter-gatherers, pastoral nomads (owning livestock), tinkers and trader nomads. In the twentieth century, the population of nomadic pa ...
ic bird, and because population fluctuations in its prey
Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not ki ...
species can force it to relocate, it has been known to breed at more southerly latitudes. Although the total breeding range includes a little over , only about have a high probability of breeding, i.e. breeding at no more than 3–9-year intervals.[ Snowy owls nest in the Arctic ]tundra
In physical geography, a tundra () is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. There are three regions and associated types of tundra: #Arctic, Arctic, Alpine tundra, Alpine, and #Antarctic ...
of the northernmost stretches of Alaska
Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...
, Northern Canada, and the Euro-Siberian region.[
Between 1967 and 1975, snowy owls bred on the remote island of Fetlar in the ]Shetland
Shetland (until 1975 spelled Zetland), also called the Shetland Islands, is an archipelago in Scotland lying between Orkney, the Faroe Islands, and Norway, marking the northernmost region of the United Kingdom. The islands lie about to the ...
Isles north of mainland Scotland
Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...
, discovered by the Shetland RSPB
The Royal Society for the Protection of Birds (RSPB) is a Charitable_organization#United_Kingdom, charitable organisation registered in Charity Commission for England and Wales, England and Wales and in Office of the Scottish Charity Regulator, ...
warden, Bobby Tulloch. Females summered as recently as 1993, but their status in the British Isles
The British Isles are an archipelago in the Atlantic Ocean, North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner Hebrides, Inner and Outer Hebr ...
is now that of a rare winter visitor to Shetland, the Outer Hebrides
The Outer Hebrides ( ) or Western Isles ( , or ), sometimes known as the Long Isle or Long Island (), is an Archipelago, island chain off the west coast of mainland Scotland.
It is the longest archipelago in the British Isles. The islan ...
and the Cairngorms
The Cairngorms () are a mountain range in the eastern Scottish Highlands, Highlands of Scotland closely associated with the mountain Cairn Gorm. The Cairngorms became part of Scotland's second national parks of Scotland, national park (the Cairn ...
. Vagrant
Vagrancy is the condition of wandering homelessness without regular employment or income. Vagrants usually live in poverty and support themselves by travelling while engaging in begging, scavenging, or petty theft. In Western countries, ...
snowy owls have occasionally been found as far south as Lincolnshire
Lincolnshire (), abbreviated ''Lincs'', is a Ceremonial counties of England, ceremonial county in the East Midlands and Yorkshire and the Humber regions of England. It is bordered by the East Riding of Yorkshire across the Humber estuary to th ...
. Older records show that the snowy owls may have once semi-regularly bred elsewhere in Shetland
Shetland (until 1975 spelled Zetland), also called the Shetland Islands, is an archipelago in Scotland lying between Orkney, the Faroe Islands, and Norway, marking the northernmost region of the United Kingdom. The islands lie about to the ...
. They range in northern Greenland (mostly Peary Land) and, rarely in "isolated parts of the highlands", Iceland.[ Thence, they are found breeding at times across northern ]Eurasia
Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...
such as in Spitsbergen
Spitsbergen (; formerly known as West Spitsbergen; Norwegian language, Norwegian: ''Vest Spitsbergen'' or ''Vestspitsbergen'' , also sometimes spelled Spitzbergen) is the largest and the only permanently populated island of the Svalbard archipel ...
and western and northern Scandinavia
Scandinavia is a subregion#Europe, subregion of northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. ''Scandinavia'' most commonly refers to Denmark, Norway, and Sweden. It can sometimes also ...
. In Norway, they normally breed in Finnmark
Finnmark (; ; ; ; ) is a counties of Norway, county in northern Norway. By land, it borders Troms county to the west, Finland's Lapland (Finland), Lapland region to the south, and Russia's Murmansk Oblast to the east, and by water, the Norweg ...
and seldom down as far south as Hardangervidda
Hardangervidda () is a mountain plateau ( Norwegian: ''vidde'') in central southern Norway, covering parts of Vestland, Telemark, and Buskerud counties. It is the largest plateau of its kind in Europe, with a cold year-round alpine climate, and o ...
and in Sweden perhaps down to the Scandinavian Mountains
The Scandinavian Mountains or the Scandes is a mountain range that runs through the Scandinavian Peninsula. The western sides of the mountains drop precipitously into the North Sea and Norwegian Sea, forming the fjords of Norway, whereas to th ...
while breeding is very inconsistent in Finland.[
They also range in much of northern Russia, including northern ]Siberia
Siberia ( ; , ) is an extensive geographical region comprising all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has formed a part of the sovereign territory of Russia and its predecessor states ...
, Anadyr, Koryakland, Taymyr Peninsula
The Taymyr Peninsula ( ) is a peninsula in the Far North of Russia, in the Siberian Federal District, that forms the northernmost part of the mainland of Eurasia. Administratively it is part of the Krasnoyarsk Krai Federal subject of Russia.
Ge ...
, Yugorsky Peninsula, Sakha (especially the Chukochya River) and Sakhalin
Sakhalin ( rus, Сахали́н, p=səxɐˈlʲin) is an island in Northeast Asia. Its north coast lies off the southeastern coast of Khabarovsk Krai in Russia, while its southern tip lies north of the Japanese island of Hokkaido. An islan ...
.[ Breeding has also been reported sporadically to the south in the ]Komi Republic
The Komi Republic (; ), sometimes simply referred to as Komi, is a republics of Russia, republic of Russia situated in the northeast of European Russia. Its capital city, capital is the types of inhabited localities in Russia, city of Syktyvka ...
and even the in southern Perm Krai
Perm Krai (, ; ) is a federal subjects of Russia, federal subject of Russia (a Krais of Russia, krai), located in Eastern Europe. Its administrative center is Perm, Russia, Perm. The population of the krai was 2,532,405 (2021 Russian census, 2021 ...
.[ Although considered part of their regular range, the last breeding by snowy owls in the ]Kola Peninsula
The Kola Peninsula (; ) is a peninsula in the extreme northwest of Russia, and one of the largest peninsulas of Europe. Constituting the bulk of the territory of Murmansk Oblast, it lies almost completely inside the Arctic Circle and is border ...
was in the early 1980s; similarly, breeding maps show the species in Arkhangelsk Oblast
Arkhangelsk Oblast ( rus, Архангельская область, p=ɐrˈxanɡʲɪlʲskəjə ˈobɫəsʲtʲ) is a federal subjects of Russia, federal subject of Russia (an oblast). It includes the Arctic Ocean, Arctic archipelagos of Franz ...
and the Pay-Khoy Ridge but no breeding records are known in at least 30 years in either. They range throughout most of the Arctic isles of Russia such as Novaya Zemlya
Novaya Zemlya (, also , ; , ; ), also spelled , is an archipelago in northern Russia. It is situated in the Arctic Ocean, in the extreme northeast of Europe, with Cape Flissingsky, on the northern island, considered the extreme points of Europe ...
, Severnaya Zemlya, New Siberian Islands, Wrangel Island
Wrangel Island (, ; , , ) is an island of the Chukotka Autonomous Okrug, Russia. It is the List of islands by area, 92nd-largest island in the world and roughly the size of Crete. Located in the Arctic Ocean between the Chukchi Sea and East Si ...
, Commander
Commander (commonly abbreviated as Cmdr.) is a common naval officer rank as well as a job title in many army, armies. Commander is also used as a rank or title in other formal organizations, including several police forces. In several countri ...
and Hall Islands.[
In North America, the breeding range has been known in modern times to include the Aleutians (i.e. Buldir and Attu) and much of northern ]Alaska
Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...
, most frequently from the Arctic National Wildlife Refuge to Utqiaġvik
Utqiagvik ( ; , ), formerly known as Barrow ( ), is the borough seat and largest city of the North Slope Borough, Alaska, North Slope Borough in the U.S. state of Alaska. Located north of the Arctic Circle, it is one of the List of northernmost ...
, and more sporadically down along the coastal-western parts such as through Nome, Hooper Bay, the Yukon Delta National Wildlife Refuge, and rarely even south to the Shumagin Islands.[ The snowy owl may breed extensively in northern Canada, largely making its home in the ]Arctic Archipelago
The Arctic Archipelago, also known as the Canadian Arctic Archipelago, is an archipelago lying to the north of the Canadian continental mainland, excluding Greenland (an autonomous territory of the Danish Realm, which is, by itself, much larger ...
.[ Their Canadian breeding range can include broadly ]Ellesmere Island
Ellesmere Island (; ) is Canada's northernmost and List of Canadian islands by area, third largest island, and the List of islands by area, tenth largest in the world. It comprises an area of , slightly smaller than Great Britain, and the total ...
up to Cape Sheridan, north coastal Labrador
Labrador () is a geographic and cultural region within the Canadian province of Newfoundland and Labrador. It is the primarily continental portion of the province and constitutes 71% of the province's area but is home to only 6% of its populatio ...
, the northern Hudson Bay
Hudson Bay, sometimes called Hudson's Bay (usually historically), is a large body of Saline water, saltwater in northeastern Canada with a surface area of . It is located north of Ontario, west of Quebec, northeast of Manitoba, and southeast o ...
, perhaps all of Nunavut
Nunavut is the largest and northernmost Provinces and territories of Canada#Territories, territory of Canada. It was separated officially from the Northwest Territories on April 1, 1999, via the ''Nunavut Act'' and the Nunavut Land Claims Agr ...
(especially the Kivalliq Region
The Kivalliq Region (; Inuktitut syllabics: ᑭᕙᓪᓕᖅ) is an Region, administrative List of regions of Nunavut, region of Nunavut, Canada. It consists of the portion of the mainland to the west of Hudson Bay together with Southampton Island ...
), northeastern Manitoba
Manitoba is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population ...
, most of northern mainland and insular Northwest Territories
The Northwest Territories is a federal Provinces and territories of Canada, territory of Canada. At a land area of approximately and a 2021 census population of 41,070, it is the second-largest and the most populous of Provinces and territorie ...
(including the delta
Delta commonly refers to:
* Delta (letter) (Δ or δ), the fourth letter of the Greek alphabet
* D (NATO phonetic alphabet: "Delta"), the fourth letter in the Latin alphabet
* River delta, at a river mouth
* Delta Air Lines, a major US carrier ...
of the Mackenzie River
The Mackenzie River (French: ; Slavey language, Slavey: ' èh tʃʰò literally ''big river''; Inuvialuktun: ' uːkpɑk literally ''great river'') is a river in the Canadian Canadian boreal forest, boreal forest and tundra. It forms, ...
) and northern Yukon Territory
Yukon () is a territory of Canada, bordering British Columbia to the south, the Northwest Territories to the east, the Beaufort Sea to the north, and the U.S. state of Alaska to the west. It is Canada’s westernmost territory and the smallest ...
(where breeding is mostly confined to Herschel Island).[ Since breeding and distribution is very small, local and inconsistent in northern Europe, northern Canada and northern Alaska represent the core part of the breeding range for snowy owls along with several parts of northern and northeastern/coastal Russia.][
]
Regular wintering range
During the winter months, many snowy owls leave the dark Arctic to migrate to regions further south. Southern limits of the regular winter range are difficult to delineate given the inconsistency of appearances south of the Arctic.[ Furthermore, not infrequently, many snowy owls will overwinter somewhere in the Arctic through the winter, though seldom appear to do so in the same sites where they have bred.][ Due in no small part to the difficulty and hazardousness of observation for biologists during these harsh times, there is very limited data on overwintering snowy owls in the tundra, including how many occur, where they winter and what their ecology is at this season.][
The regular wintering range has at times been thought to include Iceland, Ireland and Scotland and across northern Eurasia such as southern Scandinavia, the ]Baltics
The Baltic states or the Baltic countries is a geopolitical term encompassing Estonia, Latvia, and Lithuania. All three countries are members of NATO, the European Union, the Eurozone, and the OECD. The three sovereign states on the eastern co ...
, central Russia, southwestern Siberia
Siberia ( ; , ) is an extensive geographical region comprising all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has formed a part of the sovereign territory of Russia and its predecessor states ...
, Sakhalin
Sakhalin ( rus, Сахали́н, p=səxɐˈlʲin) is an island in Northeast Asia. Its north coast lies off the southeastern coast of Khabarovsk Krai in Russia, while its southern tip lies north of the Japanese island of Hokkaido. An islan ...
southern Kamchatka
The Kamchatka Peninsula (, ) is a peninsula in the Russian Far East, with an area of about . The Pacific Ocean and the Sea of Okhotsk make up the peninsula's eastern and western coastlines, respectively.
Immediately offshore along the Pacific ...
and, rarely, north China and sometimes the Altai Republic
The Altai Republic, also known as the Gorno-Altai Republic, is a republic of Russia located in southern Siberia. The republic borders Kemerovo Oblast to the north, Khakassia to the northeast, Tuva to the east, Altai Krai to the west, as well ...
.[ In North America, they occasionally regularly winter in the Aleutian island chain and do so broadly and with a fair amount of consistency in much of southern Canada, from ]British Columbia
British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...
to Labrador
Labrador () is a geographic and cultural region within the Canadian province of Newfoundland and Labrador. It is the primarily continental portion of the province and constitutes 71% of the province's area but is home to only 6% of its populatio ...
.[ Recent research has indicated that snowy owls regularly winter in several of the northern seas during wintertime, following the leads of ]sea ice
Sea ice arises as seawater freezes. Because ice is less density, dense than water, it floats on the ocean's surface (as does fresh water ice). Sea ice covers about 7% of the Earth's surface and about 12% of the world's oceans. Much of the world' ...
as perching sites and presumably hunting mostly seabird
Seabirds (also known as marine birds) are birds that are adaptation, adapted to life within the marine ecosystem, marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent ...
s in polynya
A polynya () is an area of open water surrounded by sea ice. It is now used as a geographical term for an area of unfrozen seawater within otherwise contiguous pack ice or fast ice. It is a loanword from the Russian language, Russian (), whic ...
s.
In February 1886, a snowy owl landed on the rigging of the Nova Scotia
Nova Scotia is a Provinces and territories of Canada, province of Canada, located on its east coast. It is one of the three Maritime Canada, Maritime provinces and Population of Canada by province and territory, most populous province in Atlan ...
steamship ''Ulunda'' on the edge of the Grand Banks of Newfoundland, over from the nearest land. It was captured and later preserved at the Nova Scotia Museum. Surprisingly, some studies have determined that after a high lemming year in North America, a higher percentage of snowy owls were using marine environments rather than inland ones.
Irruptive range
Large winter irruptions at temperate latitudes are thought to be due to good breeding conditions resulting in more juvenile migrants.[ These result in irruptions occurring further south than the typical snowy owl range in some years.] They have been reported, as well as in all northerly states in the contiguous states, as far south as Georgia
Georgia most commonly refers to:
* Georgia (country), a country in the South Caucasus
* Georgia (U.S. state), a state in the southeastern United States
Georgia may also refer to:
People and fictional characters
* Georgia (name), a list of pe ...
, Kentucky
Kentucky (, ), officially the Commonwealth of Kentucky, is a landlocked U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders Illinois, Indiana, and Ohio to the north, West Virginia to the ...
, South Carolina
South Carolina ( ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders North Carolina to the north and northeast, the Atlantic Ocean to the southeast, and Georgia (U.S. state), Georg ...
, nearly all the Gulf Coast of the United States
The Gulf Coast of the United States, also known as the Gulf South or the South Coast, is the coastline along the Southern United States where they meet the Gulf of Mexico. The list of U.S. states and territories by coastline, coastal states th ...
, Colorado
Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...
, Nevada
Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...
, Texas
Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...
, Utah
Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...
, California and even Hawaii.[ In January 2009, a snowy owl appeared in Spring Hill, Tennessee, the first reported sighting in the state since 1987. Also notable is the mass southern migration in the winter of 2011/2012, when thousands of snowy owls were spotted in various locations across the United States. This was then followed by an even larger mass southern migration in 2013/2014 with the first snowy owls seen in Florida for decades. The nature of irruptions is less well-documented in Eurasia, in part due to the paucity of this owl in the European side, but accidental occurrence, presumably during irruptions, has been described in the ]Mediterranean
The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern ...
area, France, Crimea
Crimea ( ) is a peninsula in Eastern Europe, on the northern coast of the Black Sea, almost entirely surrounded by the Black Sea and the smaller Sea of Azov. The Isthmus of Perekop connects the peninsula to Kherson Oblast in mainland Ukrain ...
, the Caspian part of Iran, Kazakhstan, northern Pakistan, northwestern India, Korea and Japan.[ Stragglers may too turn up as far south as the ]Azores
The Azores ( , , ; , ), officially the Autonomous Region of the Azores (), is one of the two autonomous regions of Portugal (along with Madeira). It is an archipelago composed of nine volcanic islands in the Macaronesia region of the North Atl ...
and Bermuda.[
]
Habitat
Snowy owls are one of the best known inhabitants of the open Arctic tundra
In physical geography, a tundra () is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. There are three regions and associated types of tundra: #Arctic, Arctic, Alpine tundra, Alpine, and #Antarctic ...
. Frequently, the earth in snowy owl breeding grounds is covered with moss
Mosses are small, non-vascular plant, non-vascular flowerless plants in the taxonomic phylum, division Bryophyta (, ) ''sensu stricto''. Bryophyta (''sensu lato'', Wilhelm Philippe Schimper, Schimp. 1879) may also refer to the parent group bryo ...
es, lichen
A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...
s and some rocks. Often the species preferentially occurs in areas with some rising elevation such as hummocks, knolls, ridge
A ridge is a long, narrow, elevated geomorphologic landform, structural feature, or a combination of both separated from the surrounding terrain by steep sides. The sides of a ridge slope away from a narrow top, the crest or ridgecrest, wi ...
s, bluffs and rocky outcrops.[ Some of these rises in the tundra are created by glacial deposits.][ The ground is usually rather dry in tundra but in some areas of the southern tundra can also be quite ]marsh
In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in genera ...
y.[ Not infrequently, they will also use areas of varied ]coast
A coast (coastline, shoreline, seashore) is the land next to the sea or the line that forms the boundary between the land and the ocean or a lake. Coasts are influenced by the topography of the surrounding landscape and by aquatic erosion, su ...
al habitat, often tidal flats, as a breeding site. Breeding sites are usually at low elevations, usually less than above sea level, but when breeding to the south in inland mountains, such as in Norway, they may nest at as high as .[ Outside the breeding season, snowy owls may occupy nearly any open landscape.][
Typically wintering sites are rather windswept with meager cover.][ These open areas can include coastal dunes, other ]coast
A coast (coastline, shoreline, seashore) is the land next to the sea or the line that forms the boundary between the land and the ocean or a lake. Coasts are influenced by the topography of the surrounding landscape and by aquatic erosion, su ...
al spots, lakeshores, islands, moorland
Moorland or moor is a type of Habitat (ecology), habitat found in upland (geology), upland areas in temperate grasslands, savannas, and shrublands and the biomes of montane grasslands and shrublands, characterised by low-growing vegetation on So ...
s, steppe
In physical geography, a steppe () is an ecoregion characterized by grassland plains without closed forests except near rivers and lakes.
Steppe biomes may include:
* the montane grasslands and shrublands biome
* the tropical and subtropica ...
s, meadow
A meadow ( ) is an open habitat or field, vegetated by grasses, herbs, and other non- woody plants. Trees or shrubs may sparsely populate meadows, as long as they maintain an open character. Meadows can occur naturally under favourable con ...
s, prairie
Prairies are ecosystems considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and a composition of grasses, herbs, and shrubs, rather than trees, as the ...
s, other extensive grassland
A grassland is an area where the vegetation is dominance (ecology), dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes such as clover, and other Herbaceo ...
s and rather shrub
A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...
by areas of the Subarctic
The subarctic zone is a region in the Northern Hemisphere immediately south of the true Arctic, north of hemiboreal regions and covering much of Alaska, Canada, Iceland, the north of Fennoscandia, Northwestern Russia, Siberia, and the Cair ...
. These may be favored due to their vague similarity to the flat openness of the tundra.[ Manmade open sites are now perhaps even more used than natural ones, often agricultural fields and ]rangeland
Rangelands are grasslands, shrublands, woodlands, wetlands, and deserts that are grazed by domestic livestock or wild animals. Types of rangelands include tallgrass and shortgrass prairies, desert grasslands and shrublands, woodlands, savanna ...
, as well as large areas of cleared forests. During irruption years when they are found in the northeastern United States, juveniles frequent developed areas including urban areas and golf course
A golf course is the grounds on which the sport of golf is played. It consists of a series of holes, each consisting of a teeing ground, tee box, a #Fairway and rough, fairway, the #Fairway and rough, rough and other hazard (golf), hazards, and ...
s, as well as the expected grassland
A grassland is an area where the vegetation is dominance (ecology), dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes such as clover, and other Herbaceo ...
s and agricultural areas that older birds primarily use.[
On the plains of Alberta, observed snowy owls spent 30% of their time in stubble-fields, 30% in summer fallow, 14% in hayfield and the remainder of the time in ]pasture
Pasture (from the Latin ''pastus'', past participle of ''pascere'', "to feed") is land used for grazing.
Types of pasture
Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, c ...
, natural grasslands and slough
Slough () is a town in Berkshire, England, in the Thames Valley, west of central London and north-east of Reading, at the intersection of the M4, M40 and M25 motorways. It is part of the historic county of Buckinghamshire. In 2021, the ...
s. The agricultural areas, large untouched by the farmers in winter, may have had more concentrated prey than the others in Alberta.
Perhaps the most consistently attractive habitat in North America to wintering snowy owls in modern times may be airports, which not only tend to have the flat, grassy characteristics of their preferred habitats but also by winter host a particular diversity of prey, both pests
PESTS was an anonymous American activist group formed in 1986 to critique racism, tokenism, and exclusion in the art world. PESTS produced newsletters, posters, and other print material highlighting examples of discrimination in gallery represent ...
which rely on humans as well as wildlife attracted to the extensively grassy and marshy strips that dot the large airport vicinities. For example, Logan International Airport in Massachusetts
Massachusetts ( ; ), officially the Commonwealth of Massachusetts, is a U.S. state, state in the New England region of the Northeastern United States. It borders the Atlantic Ocean and the Gulf of Maine to its east, Connecticut and Rhode ...
has relatively one of the most reliable annual populations known in the United States in winter.[ All ages spend a fair amount of their time over water in the ]Bering Sea
The Bering Sea ( , ; rus, Бе́рингово мо́ре, r=Béringovo móre, p=ˈbʲerʲɪnɡəvə ˈmorʲe) is a marginal sea of the Northern Pacific Ocean. It forms, along with the Bering Strait, the divide between the two largest landmasse ...
, the Atlantic Ocean and even the Great Lakes
The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes spanning the Canada–United States border. The five lakes are Lake Superior, Superior, Lake Michigan, Michigan, Lake Huron, H ...
, mostly on ice floes.[ These marine and ocean-like freshwater areas were observed to account for 22–31% of habitat used in 34 radio-tagged American snowy owls over two irruptive years, with the tagged owls occurring a mean of from the nearest land (while 35–58% used the expected preferred habitats of grassland, pasture and other agricultural land).][
]
Behavior
Snowy owls may be active to some extent at both day, from dawn to dusk, and night.[ Snowy owls have been seen to be active even during the very brief winter daytime in the northern winter.][ During the Arctic summer, snowy owls may tend to peak in activity during the twilight that is the darkest time available given the lack of full nightfall.] Reportedly, the peak time of activity during summer is between 9:00 pm and 3:00 am in Norway.[Hagen, Y. (1960). ''The Snowy Owl on Hardangervidda in the Summer of 1959''. Papers of The Norwegian State Game Research. 2, No. 7.] The peak time of activity for those owls that once nested on Fetlar was reported between 10:00 and 11:00 pm.
According to one authority, the least active times are at noon and midnight.[ As days become longer near autumn in ]Utqiaġvik
Utqiagvik ( ; , ), formerly known as Barrow ( ), is the borough seat and largest city of the North Slope Borough, Alaska, North Slope Borough in the U.S. state of Alaska. Located north of the Arctic Circle, it is one of the List of northernmost ...
, the snowy owls in the tundra become more active around nightfall and can often be seen resting during the day, especially if it is raining.[ During winter in ]Alberta
Alberta is a Provinces and territories of Canada, province in Canada. It is a part of Western Canada and is one of the three Canadian Prairies, prairie provinces. Alberta is bordered by British Columbia to its west, Saskatchewan to its east, t ...
, snowy owls were tracked in the daytime, despite being also active at night (as they were deemed too difficult to track). In the study, they were most active during 8:00–10:00 am and 4:00–6:00 pm and often rested mostly from 10:00 am to 4:00 pm. The owls were perched for 98% of observed daylight and seemed to time their activity to peak times for rodents. The variation of activity is probably in correspondence with their primary prey, the lemming
A lemming is a small rodent, usually found in or near the Arctic in tundra biomes. Lemmings form the subfamily Arvicolinae (also known as Microtinae) together with voles and muskrats, which form part of the superfamily Muroidea, which also inclu ...
s, and like them, the snowy owl may be considered cathemeral. This species can withstand extremely cold temperatures, having been recorded in temperatures as low as minus 62.5 degrees Celsius with no obvious discomfort and also withstood a 5-hour exposure to minus 93 degrees Celsius but may have struggled with oxygen consumption by the end of this period. The snowy owl has perhaps the second lowest thermal conduction
Thermal conduction is the diffusion of thermal energy (heat) within one material or between materials in contact. The higher temperature object has molecules with more kinetic energy; collisions between molecules distributes this kinetic energy ...
to the plumage on average of any bird after only the Adelie penguin (''Pygoscelis adeliae'') and rivals the best insulated mammals, such as Dall sheep (''Ovis dalli'') and Arctic fox
The Arctic fox (''Vulpes lagopus''), also known as the white fox, polar fox, or snow fox, is a small species of fox native to the Arctic regions of the Northern Hemisphere and common throughout the Tundra#Arctic tundra, Arctic tundra biome. I ...
, as the best insulated polar creature.[ Presumably as many as seven rodents would need to be eaten daily to survive an extremely cold winter's day.][
Adults and young both have been seen to shelter behind rocks to shield themselves from particularly harsh winds or storms.][ Snowy owls often spending a majority of time on the ground, perched mostly on a slight rise of elevation.][ It has been interpreted from the morphology of their skeletal structure (i.e. their short, broad legs) that snowy owls are not well-suited to perching extensively in trees or rocks and prefer a flat surface to sit upon.][ However, they may perch more so in winter though do so only mainly when hunting, at times on hummocks, ]fence
A fence is a structure that encloses an area, typically outdoors, and is usually constructed from posts that are connected by boards, wire, rails or net (textile), netting. A fence differs from a wall in not having a solid foundation along its ...
posts, telegraph poles by roads, radio
Radio is the technology of communicating using radio waves. Radio waves are electromagnetic waves of frequency between 3 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connec ...
and transmission tower
A transmission tower (also electricity pylon, hydro tower, or pylon) is a tall structure, usually a lattice tower made of steel that is used to support an overhead power line. In electrical grids, transmission towers carry high-voltage transmis ...
s, haystacks, chimney
A chimney is an architectural ventilation structure made of masonry, clay or metal that isolates hot toxic exhaust gases or smoke produced by a boiler, stove, furnace, incinerator, or fireplace from human living areas. Chimneys are typical ...
s and the roofs of houses and large buildings.[ Rocks may be used as perches at times in all seasons.][ Though often relatively sluggish owls, like most related species, they are capable of sudden dashing movements in various contexts.][
Snowy owls can walk and run quite quickly, using outstretched wings for balance if necessary.][ This owl flies with fairly rowing wingbeats, occasionally interrupted by gliding on stretched wings. The flight is fairly buoyant for a ''Bubo'' owl.][ When displaying, the male may engage in an undulating flight with interspersed wingbeats and gliding in a slight dihedral, finally dropping rather vertically to the ground.][ They are capable for swimming but do not usually do so. Some seen to be swimming were previously injured but young have been seen to swim into water to escape predators if they cannot fly yet. They will also drink when unfrozen water is available.]