Snowy owl (Bubo scandiacus)
Snowy owls rank among the most charismatic wildlife species in the world. The heaviest of all North American owls, tipping the scales at 3 to 6 pounds, their bright white plumage, large yellow eyes, massive feathered feet and diurnal tendencies appeal to even the most casual nature lover. Equally appealing to some are their unpredictable movement patterns and the remote arctic wilderness they represent.
As their name suggests snowy owls are generally a northern species, nesting worldwide on the treeless tundra above the Arctic Circle. During a typical winter, some remain close to their breeding areas while others head south into southern Canada and the northern United States. At least small numbers reach Wisconsin each year. Every handful of years, however, large numbers move into the state, an event known as an "irruption."
- How To Spot A Snowy Owl In Wisconsin This Winter [exit DNR]
DNR Conservation Biologist Ryan Brady discusses snowy owls on Central Time on Wisconsin Public Radio
- 2020-21 Update
As of March 8, small numbers of snowy owls remain scattered over mostly the southern two-thirds of Wisconsin. Overall, this has not been an irruption year, meaning large numbers of snowies never made it to Wisconsin or anywhere in the lower 48. Migration will get underway any time now as the birds begin to head north to the Arctic tundra of Canada. By mid-April the majority will be north of Wisconsin. Until then, there’s still time to visit areas that traditionally host wintering owls, such as Buena Vista Wildlife Area in Portage County, the Freedom area in Outagamie County, and agricultural fields near Green Lake and Dodge counties. Migrating owls can also show up in just about any non-wooded habitat, so keep your eyes open. Visit eBird for an updated map of recent sightings and to report your own sightings of snowy owls and other birds. Happy owling!
- Causes of an irruption
In short, no one knows with certainty. Most experts agree these periodic mass movements are associated in some way with their primary northern prey source, a small rodent known as a lemming. Traditional thought suggested that a temporary "crash", or shortage, of lemmings, pushes owls southward in search of food. However, more recent evidence suggests nearly the opposite, that a temporary abundance of lemmings allows the owls to successfully raise large families, and then these young owls disperse southward by the hundreds to avoid competition with older birds for winter territories.
It's even possible, perhaps likely, that not all irruptions are created equal and both mechanisms play out in some years. Unfortunately, the population dynamics of lemmings are complex and poorly understood. The same can be said for snowy owls, in large part because of the remote northern haunts they occupy most of the year. This no doubt elevates their intrigue but serves as a barrier to understanding and ultimately conserving the species.
- Are they starving?
Contrary to popular myth, it's not all doom-and-gloom when snowy owls visit the Lower 48 in large numbers. The notion that "they're all starving" is an outdated and erroneous one. In fact, many experts opine -- and have the data to support it -- that many of the birds fare quite well during their time here, aside from impacts of anthropogenic mortality sources such as collisions with vehicles, electrocution, secondary rodenticide poisoning and illegal shooting.
On the other hand, there are also good data from wildlife rehabilitators and elsewhere to show that in some irruptions a significant number, perhaps a majority even, arrive in southern wintering areas in poor body condition, exhausted or emaciated from the long journey. Some of them will recuperate upon arrival, others will perish. Unfortunately such is the way of all migratory birds, whose fate we don't often follow with such watchful eyes. For example, juvenile raptors typically have a mortality rate near 70% in their first year. Overall, it's complicated!
- Tips for finding one - know their habits
Seeing a snowy owl in the wild is a thrilling experience and highly sought by many birders and non-birders alike. You can improve your chances by understanding the species' habits. In short, check low-level perches in open habitats around dawn or dusk from November to March. More details are below.
Snowy owls usually seek out open habitats similar to the arctic tundra they call home. Common habitats include coastal beaches and harbors, open grasslands and agricultural fields, wetland complexes, airports and vast expanses of ice-covered water bodies. They are not averse to civilization, however, and are often found in suburban or even urban settings.
In these habitats, they'll roost on just about anything, including the ground, haybales, fenceposts, telephone poles, rocky breakwalls, muskrat houses, trees and snags, silos and other structures. Beware of white plastic bags which, as too many birdwatchers can attest to, seem to be far more common than the real thing!
From these perches, snowy owls are seeking nearly anything that moves. Their diet is varied, though many foci on voles, mice, shrews and other small lemming-like rodents for food. Ducks and other waterbirds are surprisingly common prey sources, while rabbits, weasels, muskrats, pigeons and other birds are also regularly taken.
Time of day
Snowy owls are notorious for being diurnal, or active during the day, unlike many other owl species. This makes sense for a bird that nests in the perpetual daylight of an Arctic summer. However, during the winter the birds tend to be most active at crepuscular periods, meaning around the times of dawn and dusk. Some hunt throughout the darkness of night, while others are quite active in broad daylight. Bottom line? You can see one any time of day, though dawn and dusk may improve your chances.
Time of year
In most years snowy owls arrive around mid-November and depart by the end of March. In some years they arrive as early as mid-October and linger well into April or even May. Early-season birds are often on the move and can't be relocated in the same location day after day. By later in December and January most establish winter territories that hold them to a smaller area on a repeat basis.
eBird is an online program for reporting and viewing bird observations around the world. One of its features is to Explore Data, where among other options you can select a customized species map that shows all the snowy owls that have been seen and reported to eBird. Consulting the map of recent observations can be a good way to find out where and when the birds have been seen.
Other online tools
Like some of the species, they follow birders tend to be a gregarious bunch. Listserves, Facebook groups, and other online forums are excellent ways to learn about who's seeing what and where. Find some of these resources online.
- Viewing considerations
Like all birds, snowy owls deserve our care and respect when viewing them. Some may be exhausted or even emaciated from their flight south, others may be battling the hardship of a Wisconsin winter and all will fare better if we give them adequate space to hunt and rest free of disturbance. Some general recommendations for observing snowy owls include:
- do not approach an owl too closely -- you are too close if the bird frequently looks at you, sits erect with open eyes peering in your direction or flushes from its perch;
- avoid repeated flushing;
- do not play audio recordings from smartphones or other devices;
- do not feed owls mice or other prey, which may lead to unintended negative impacts, like habituation to people, higher likelihood of vehicle collision and disease;
- minimize the use of flash photography, especially after dark, as this can disrupt an owl's activity patterns;
- when viewing from a vehicle (recommended!), turn off the engine to avoid interfering with the owl's auditory hunting technique;
- ask landowner permission before frequenting private property; and
- avoid blocking public roadways and access points.
In many cases, you may not be the only person to see the owl, and the cumulative impacts of these repeated actions can be especially harmful. Please visit the Wisconsin Society for Ornithology's Code of Ethics for more details.
- Popular snowy owl resources
Most links exit DNR.
- Cornell's All About Birds: Snowy Owl
- Project SNOWstorm
- NPR’s Secrets of the Snowy Owl
- The difficulty of aging and sexing snowy owls from snowy owl expert, Denver Holt
- The difficulty of aging and sexing snowy owls from experts at Project SNOWstorm
- Aging and sexing snowy owls
- Aging and sexing snowy owls
- Dispelling the snowy owl starvation myth
- Snowy owl migration: more complicated than most people realize
- PBS Nature: Magic of the Snowy Owl (full episode online)
- A swimming snowy owl on Lake Superior
- Wisconsin Society for Ornithology's Code of Ethics
- Wisconsin Society for Ornithology's Find Birds
- Wisconsin eBird