Originally assigned the binomen Nyctea scandiaca, from the Greek nuktios meaning "night", the Snowy owl was reclassified into the Strix genus by Linnaeus in 1758 and Bubo genus in 2003 based on mtDNA cytochrome b sequence data that groups it closely with the horned owls. Palaeolithic cave paintings from Les Trois Frères in the Ariège department of south-western France appear to depict Snowy owls with their young, making it one of the oldest bird species recognized in prehistoric art. This owl also appears to have a long history with indigenous Arctic peoples (e.g., Inuit communities), who occasionally hunted them and collected their eggs food, as well as including them in ivory and bone carvings.
That which follows is a short history of the Snowy owl.
The Snowy owl at a glance
Size: A large stringid standing 53-66 cm (20-26 in.) tall and with a wing span of 140-170 cm (4.5-5.5 ft.). Adults weigh between 1.2 and 3 kg (2.6-6 lbs), with females both larger and heavier than males. Males average about 1.7 kg (3.7 lbs), females 2.2 kg (4.8 lbs).
Appearance: An unmistakable owl with a comparatively small but pronounced rounded head that lacks a complete facial disc, the feathers above the eyes being arranged normally rather than radially as in other owls. Both sexes have small ear tufts, but these are seldom seen. The plumage is striking white with varying amounts of dark bars and speckles, ranging in colour from black through to grey and brown, that extends down to their toes and provides exceptional insulation. Indeed, these birds have a thermal conduction similar to that of the Arctic fox, only trumped by the Adelie penguin, allowing them to survive down to at least -34C (-29F). Moults run from July to September, sometimes May to October, and are not extensive enough to prevent the bird flying.
Distribution: A native of the Arctic, Snowy owls are considered an occasional vagrant to the UK and have been recorded over various parts of Scotland in the past decade (i.e., Shetland, the Outer Hebrides, and the Cairngorms), although the odd bird has been spotted as far south as Lincolnshire, including an individual photographed at Wainfleet Marsh in East Lindsey during March 2018. In 1967, the Shetland island of Fetlar became famous in the ornithological community after the first confirmed report of breeding of Snowy owls in Britain, although there are anecdotal reports of breeding on the island from the mid-1800s. This celebrated pair bred on the island until 1975, raising 21 chicks, after which the male failed to return. No subsequent breeding attempts have been recorded anywhere in Britain or Ireland since then. Globally, the species has a northern circumpolar (Holarctic) distribution, from 13- down to about 55-degrees north. Breeding typically occurs on the Alaskan tundra and in Northern Canada through to north Asia (i.e., across northern parts of the Euro-Siberian region). An intriguing record exists of a specimen taken at Mardan in western Pakistan in March 1876, well outside its expected range, which appears to represent the most southerly record, albeit stragglers were reported from Bermuda and California during the winter of 1926/27.
Habitat: Predominantly a species of Arctic tundra, when visiting Britain favours mountains and moorland with short vegetation. Typically found at elevations below 300 m (985 ft.).
Longevity: A long-lived species, the oldest captive bird survived for at least 28 years, and some sources suggest a maximum longevity of 35 years. Wild individuals probably average only about 10 years. The oldest wild bird on record was a first-year female tagged in Massachusetts during 1991 and found dead in Montana in 2015, just short of 24 years old.
Sexing: Unlike most owls, female snowies are larger than males and there is some sexual dimorphism in plumage. Females are much more heavily marked than males, with dark bars across the breast, back, and wings; males are predominantly white with fewer and smaller spots and bars.
Activity: Captive studies suggest these birds are most active at dawn and least active at noon and midnight, although hunting may occur sporadically across 24 hours, particularly when feeding chicks. Scant observations in the wild suggest activity through the night, with less inclination to hunt between 03:00 and 23:00.
Territory/Home Range: Huge variation in movements and areas covered, and some very long-distance migrations have been recorded. A female rung in Utqiaġvik, Alaska, for example, migrated just over 1,928 km (1,198 mi.) along the seacoast down to Russia, before flying a slightly more direct 1,528 km (949 mi.) back; she covered at least 3,476 km (2,160 mi) in total. North American populations seem to travel more than Asian birds. Territories vary with abundance, but even in good years can be large, with breeding densities of perhaps only one pair per 9 or 10 sq-km (3-4 sq-mi.).
Diet: Snowy owls are formidable predators, taking a variety of mammalian and avian prey across their range. In their main tundra habitat, lemmings are the staple of their diet. Outside of their core range, mammals predated include rabbits and hares, voles, and shrews, while birds up to the size of geese may be taken; waders such as oystercatchers and curlew, lapwing, and sea ducks are known dietary components. They will also feed on grouse, ptarmigan, and even other raptors. Amphibians, reptiles, and fish have occasionally been reported in the diet, and the species has also been known to feed on carrion, which is a relatively uncommon behaviour among owls. While some birds may be caught in flight, most prey appears to be taken on the ground.
Reproduction: Breeds once per year and courtship incorporates calling, nest-site investigation, nuptial feeding, and a precopulatory display that involves the male lowering his head and half-raising his wings in an "angel-like" fashion. Clutches tend to be 5 to 10 eggs, although up to 16 are occasionally reported while clutches are smaller when food is in short supply. Indeed, in lemming "bust years", breeding may not even be attempted. The pure white eggs are laid into an unlined shallow natural depression, or one scraped into the ground by the female, between April and June and are incubated by the female alone. As with other owls, eggs are laid and incubated at intervals, each taking about four weeks to hatch, resulting in a significant variation in the size of nestlings. The male provides food for the female while she's incubating and both parents will noisily and aggressively defend nest sites. Both parents break-up prey to feed the chicks for the first 10 days or so, after which fledglings can handle whole prey items and can produce pellets. Chicks will leave the nest at 15-20 days old and fledging is complete by 50-60 days. Sexual maturity is reached at the end of their first year.
Behaviour & Sociality: Snowies tend to be found perched either on the ground or low objects such as hummocks, rocks, outcrops, walls or ruined buildings; they'll occasionally use posts, telegraph poles, or even house roofs, but are only rarely seen in trees. Seems to be very shy during the breeding season, readily taking flight when a disturbance is 200 m (650 ft.) or more away, while it has been observed sitting on telegraph poles or roofs while people walk around below during the winter. Both sexes will adopt the standard owl quartering behaviour -- slow, low, gliding flight with periodic hovering -- while looking for food. Males will hoot and display in flight when the nest is under threat, while the female will feign injury to draw predators away. Males produce a deep, rough hoorh hoot and a harsh, grating bark described as an ergh-ergh-ergh-ergh, the female making a higher pitched eergh-eergh-eergh call. Both sexes also make guttural clucking and croaking noises, particularly a male presenting food to a female. Females make a hen-like clucking while encouraging the chicks to feed, and chicks will issue a high-pitched whistling-squeal begging call. Beak-snapping denotes irritation.
Threats/Conservation: Very little other than humans represent a predatory threat to adult Snowy owls, while Gyrfalcons (Falco rusticolus) and Peregrine falcons (Falco peregrinus) as well as Arctic foxes (Vulpes lagopus) have been observed preying on owlets in the nest. Gulls probably also represent a threat to eggs and young chicks. The global population size is unknown but observations from across its range suggest a decline of more than 30% between 1996 and 2020, and the species is currently listed as vulnerable by the International Union for Conservation of Nature.
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