The Arctic’s most distinctive bird of prey, the snowy owl spends most of its life in the tundra landscapes of the northernmost regions of the globe.
Some populations may fly south to wintering grounds throughout Canada and the northern half of the United States, but migration patterns are unpredictable and vary year on year.
Some years snowy owls may not migrate at all, but instead remain in their summer Arctic breeding grounds all year round.
Snowy owls do not have set or predictable migration patterns but are commonly associated with seasonal or periodic movement trends called irruptions. Irruptions are observed when significantly higher numbers of birds than usual migrate to regions further south than those in which they are regularly found.
Prompted by population booms in snowy owl populations, and subsequent lack of sufficient food at their summer breeding grounds to sustain them during winter months, snowy owl irruptions can lead to the presence of these unmistakable gold-eyed predators in areas in which they may not normally be spotted.
Such events are met with great interest, especially when the birds arrive unexpectedly and in large numbers. One such mass irruption was recorded in 2013-14, when thousands of snowy owls were recorded at sites across the United States, including more than 80 birds at Boston’s Logan Airport.
Snowy Owls are pretty unpredictable when it comes to migration, and instead, have irruptions.
Arrival of snowy owls at wintering sites has been recorded from late October onwards, although mid-November is more common. By early April, most birds have left to return to their breeding grounds in the Arctic Circle, although some birds have been recorded at their winter sites until as late as July on rare occasions.
One theory is that fluctuating lemming populations may hold the key to predicting and understanding snowy owl migration. Snowy owls may only migrate when food resources are not in abundance in their summer breeding grounds. As lemmings follow a ‘boom-or-bust’ population cycle, a boom year for lemmings may lead to an increase in well-fed snowy owls and subsequently more successful breeding conditions.
This increase in snowy owl populations may put an unsustainable demand on Arctic food resources, meaning that snowy owls may be forced to temporarily relocate in winter months.
When food sources are sufficient in their summer breeding grounds, snowy owls may choose not to migrate, remaining all year round on the barren tundra landscapes. The owls can withstand the harshest Arctic conditions, even in the coldest winters, provided that they have access to enough food.
Snowy owl perched on the rocks
Snowy owls do not have regular migration routes or wintering grounds that they habitually return to each year. Instead, what are known as irruption events, periodically occur, during which snowy owl populations may disperse in large numbers, and temporarily relocate to regions further afield than their usual distribution ranges.
Although snowy owls do not always migrate, when they do leave their Arctic breeding grounds, they head south and can potentially be seen in the northeastern United States in the winter.
Preferred wintering grounds include open fields and tundra-like areas of New York and New England, as well as less frequently in the Midwest and Pacific Northwest regions. Further east, snowy owls can be seen in winter months throughout northern continental Europe and central Russia, and might be occasionally observed in Iceland and the British Isles.
Snowy Owl about to take off to hunt for prey
It ultimately depends how far a snowy owl is traveling as to how long its migration journey will take. Data recorded from tracking transmitters evidences relatively high-speed flights on both winter migration and when returning to breeding grounds the following summer.
Distances of several hundred kilometers can be covered by migrating snowy owls in just a few days. It is usual for birds to rest at stopover sites for extended periods, before eventually continuing their flight.
Records from individual snowy owls that have been released with tracking devices offer a fascinating insight into typical migration journeys. This data shows that migrating snowy owls do not fly nonstop, choosing instead to break their trips into shorter stages, traveling gradually south (or north, on the return leg of their migrations), rather than completing the journey in one long flight.
Snowy owls may pause for several days or weeks at a site before moving on to their ultimate winter destination.
Snowy Owls tend to break their migration journeys into smaller stages
Snowy owls are not known to migrate in flocks, although it is not unusual for more than one bird to be seen at an overwintering site, as they tend to choose a particular type of landscape. Observation data of individual birds indicates that where migration does occur, birds may travel at similar times, following similar routes, rather than traveling together as part of a flock.
Not all snowy owls are migratory, and even individual birds that have migrated on previous occasions may not decide to make the same or similar journeys every year. A snowy owl’s migration patterns do not follow any set rules or indicators, and depend largely on the continued availability of prey, such as lemmings, voles, hares, and game birds, in the Arctic during winter months.
Snowy Owl stood on the ground
When food resources are in shorter supply, often due to an increase in the snowy owl population after a successful breeding season, some birds may travel south in search of milder climates and more abundant prey.
Typical wintering ranges extend throughout Canada and into the northern United States, particularly New England, but also into the Midwest and Pacific Northwest regions.
Wintering ranges in Europe are not especially well established, but sites, where snowy owl populations have been observed in winter months, include Iceland, the Shetlands Isles, Scandinavia, and central Russia.
Snowy owls spend summers on tundra regions in the Arctic Circle around the North Pole. Breeding sites are typically located near open water, including the coastal regions of Alaska, Scandinavia, Northern Russia, Canadian islands within the Arctic Circle, and the Aleutian Islands.
In summer months, snowy owls will often become nomadic, relocating regularly in pursuit of a greater availability of lemmings, voles, and other small rodents.
Snowy Owl flying in the early morning light
The migration patterns of snowy owls are unpredictable and may vary from year to year. They do not follow regular or set migration routes or timetables, and may not even leave their summer breeding grounds at all. They engage in irruptive migration, sporadically moving to new hunting grounds if food supplies do become problematically scarce.
Snowy owls do not hibernate and remain active through the winter months. Rather than hibernating through the harshest conditions of the winter, they adapt to their surroundings, hunting during daylight hours rather than at night when prey may be immobilized due to sub-zero temperatures.
Snowy owls’ vision is adapted to allow them to hunt in daylight as well as being active nocturnally. This adaptation is particularly important, with the long daylight hours in Arctic regions during summer months, where they cannot rely on cover of darkness in order to feed.
As snowy owls do not migrate in the traditional sense of the word, time of day is not of particular significance to their migratory activities, if they do choose to travel further afield in winter months.
As a rule, snowy owls do not migrate to Florida. On very rare occasions, during so-called major irruptions, individual birds have been spotted in the Sunshine State, but it would not be considered within their usual distribution range.
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