The Northern Naturalist #12
Snowy Owls, A Guide to Winter Owls, and a review of Birds in Winter, by Roger Pasquier, plus News and Notes, including "The Day Before Winter": a free public talk
Snowy Owl: the White Winter Visitor
A flap of white in the corner of my eye was all that caught my attention.
I turned my head, but there was nothing. Then, a flock of crows swooped in, and I saw a Snowy Owl lift up from the building roof and fly to a different perch, the black rag-shapes of the crows following in the wind.
Snowy Owls (Bubo scandiaca) show up here in Duluth every winter. They nest exclusively on the high tundra. Most move south in the winter, but some remain close to the breeding grounds. Up north, Snowy Owls eat lemmings almost exclusively. There is a theory that Snowy Owl irruptions in the south follow the fall in the population of the lemming cycle every three to five years. Research, however, has not supported this in a strong way. No doubt food supply has a strong role in their movements though. Here in the south, they eat a wide variety of prey, including ducks, grouse, carrion, and of course, rodents.
To Snowy Owls, open spaces look like home. Here they are seen mostly on open shoreline, in farm fields, and in open urban environments. They will really settle in around airports, factories, railyards, and other industrial spots with open hunting territory and a supply of rodents.
In my early years in Duluth, we used to see a lot of Snowys—sometimes 25 or 30 a year. You’d see them when you went ran errands, and I always scanned the tops of light poles along the freeway for owls. Tragically, some genius decided to clean up the rat situation in the Duluth harbor, and that made us less attractive. Some still spend the winter here, but most years, it’s fewer than ten birds.
Snowy Owls are completely feathered, except for their eyes, bill, and talons, and even these are bordered closely by insulating feathers. Their feathers insulate as well as the fur of the best-insulated mammals, like Arctic Fox. Snowys have survived the lowest recorded temperatures in the Arctic.
They are big, white birds and are unlikely to be confused with other birds. There are rare white-morph (frosty-feathered) Great Horned Owls, but these have gray faces and noticeable ear tufts (Snowys have ear tufts too, but they are small and rarely seen—you can pick them out in the photo below.) Pale Gyrfalcons are also rare and not really owl-shaped, with their long tails and tapered wings. Any bird may appear pale in headlights or a flashlight beam.
The tougher identification question is more often, “Is that a Snowy Owl or a chunk of snow-covered ice?” They will spend much of the day roosting, with their yellow eyes closed. A couple of hours before dusk they get more active and may hunt all night, if they need too. They can go up to a month without food, however, so they have flexibility.
Snowy Owls are marked with black streaks on their bodies, ranging from young females, who may be heavily streaked, to old males, who may be almost pure white. You might not be able to tell on older females or young males, but at the margins of this spectrum, you can tell tell the sex.
We don’t usually hear any vocalizations in winter, but our resident Snowy Owl bander, Dave Evans, witnessed Snowys defending hunting territories, back in the day when there were many owls here in the winter. Then they would emit a kind of scream, assume a hostile posture (head down, body parallel to the ground, and wings and tail raised). Sometimes they would even fly at each other.
The arrival of Snowy Owls at airports has sometimes caused issues for planes. These are big, heavy birds, and striking one can have consequences for the airplane as well as the owl. Some airports have used the creative method of hiring a falconer to send an eagle or other large raptor down the runway and back before a departure or arrival. The owls then moved to the side and weren’t struck. Other airports, however, apparently catch and relocate or euthanize owls.
Snowy Owls prefer to hunt from perches, although given their predilection for flat places, the perch may be as low as a few inches off the ground. When looking for Snowys, it’s a good idea to scan any perch: buildings, light poles, hay bales, propane tanks, and industrial equipment
Outside of a few rare records in spring, Snowy Owls have left our area and headed home to the tundra before the snow has melted here, so now is the time to look for one of the most beautiful birds there is.
A Guide to Winter Owls
Every winter, there is excitement about owls arriving from the north.
It’s still early this year, and there are some hints that it might be a good owl year, but it’s too early to tell. In the meantime, here’s a quick guide to the owls you might see in the months ahead.
By winter owls, I mean species that spend most of their time to our north. Small numbers may nest in southern Canada or the U.S., but the majority of the population stays near the breeding grounds. Some years, though, usually in response to a shortage of preferred prey, these species move south, and we get to see them. This is referred to as an “irruption” (a lot more individuals from species who are already here in smaller numbers) or an “invasion” (owls completely absent here in the summer).
We think of it as a “good” owl year, but it can mean it’s really a bad year for the owls. Especially in the case of Boreal Owls, I have the idea that they are under stress. Some research with Great Grays, however, indicates that a lot of the irrupting owls actually stay physically healthy. The list below includes invaders, irrupters, and resident winter owls.
Great Gray Owl
Judging by the all the photos on the internet, the Great Gray Owl (Strix nebulosa) is the most popular of the irrupting owls. Great Grays nest here in appropriate habitat, but these local nesters are rare and retiring, so when there’s an irruption of Great Grays from the north, and these big owls become easier to find, it’s news. (This year, there have been quite a few early sightings, suggesting that this might turn into a big owl year.) They are large and gray, with no ear tufts and a big facial disk. The white “bow tie” mark at the neck is visible at a distance and in most light conditions. Some Great Grays come every year, and some years, there can be dozens along the North Shore and in the Sax-Zim Bog. In such years, Great Grays will show up far and wide and well to the south as well.
Snowy Owl
Snowy Owls (Bubo scandiaca) come south every winter. This year, there are already dozens of Snowys in the United States, as far south as Indiana, Ohio, and Maryland. There have been several sightings already here near Lake Superior. They are big, white raptors with a varying extent of black marking on the body and wings. The only birds that you might mistake for Snowy Owls are white-plumaged Great Horned Owls or light Gyrfalcons. Both are rare and have different profiles. Snowy Owls do have ear tufts, but they are rarely visible.
Northern Hawk Owl
Northern Hawk Owls (Surnia ulula) show up in small numbers most years. Sometimes they will find a good spot to roost and hunt and stay in that area all winter. This site-faithfulness, and the fact that they are diurnal (active during the day—unlike the other owls in this list) make them easier to find than the other owls here. They have long tails (shaped more like hawks than the other owls), with rusty, transverse strips on the underside and bold, black frames around the face. From a distance, they look like a blob with a tail.
Boreal Owl
Boreal Owl (Aegolius funereus) is one of the hardest species to see. Their range is mostly in remote northern areas, and they are one of the most consistently nocturnal species, even among owls.
Boreal Owls are small, big-headed owls with black facial frames and raised, white “eyebrows.” They have white spots (not streaks) on the forehead, and rusty streaking on the undersides. Quite a few were banded at Hawk Ridge this fall, which indicates some migration and might mean that we’ll see more this winter.
Northern Saw-whet Owl
Northern Saw-whet Owl (Aegolius acadicus) is our smallest owl, just slightly smaller than Boreal Owl. Note the lack of black facial frames and the streaks (not spots) on the forehead. Saw-whets nest here, but most migrate to the southern U.S. in winter.
Long-eared Owl
Long-eared Owl (Asio otus) is a rare local breeder, but some also migrate south through our region in the fall. This is a medium-sized owl, with proportionally long wings.
They have orange facial disks with white tufts above and below the bill. When roosting, their long ear tufts are noticeable, and the bases of these tufts are close together. Great Horned Owls, who have similar coloration, have tufts that are spaced farther apart on the head.
Great Horned Owl
Great Horned Owl (Bubo virginianus) is the most widespread owl in North America. In the silhouetted photo above, you can see the widely-spaced ear tufts. Horned Owls do not migrate annually, though some do roam long distances during the winter. Most of the Horned Owls seen here in winter are local residents.
Barred Owl
Barred Owl (Strix varia) is our other common, local owl. They are non-migratory, so they can be seen here all year. They are generally nocturnal, but if prey is scarce, they will hunt during the day. They don’t have ear tufts; they have dark eyes and thick barring around the face and on the underside.
Other species that might be seen in our area include Short-eared Owls and Barn Owls. Short-eareds are rare breeders here, and Barn Owls are very rare. Northern Harrier (a diurnal raptor, not an owl) has facial disks and could be confused with an owl, and I have seen other hawks misidentified, but for the most part, an owl seen in the central, northern United States or southern Canada will be one of the owls in this list.
Review of Birds in Winter: Surviving the Most Difficult Season, by Roger F. Pasquier, Princeton University Press, 2019, 304 pp.
This book is a thorough review of research about seemingly everything related to birds in winter. It is clearly structured along broad ecological categories, and then within each chapter, many studies are briefly summarized (sometimes in detail).
The chapters include Responding to Winter, Preparing for Winter, Winter Ranges and Habitat Selection in Migratory Birds, Spatial and Social Organization, Survival, The Winter Day, Anticipating Spring, Departure, Conservation, and Climate Change. Where you live, you might think such a book would be mainly about birds dealing with cold and snow, etc, but the book deals with all kinds of ecological situations, including how various species behave on migratory wintering grounds. If you are a birder who travels about the world, this will make the book doubly interesting.
Pasquier has assembled an enormous collection of information. This gives the book a fairly dense textual feel, and the diversity of research makes it hard to follow a “story” across the length of a book. Given this diversity, however, Pasquier has done a good job of trying to make it cohere.
A larger coherence problem has to do with the state of ornithological research. In spite of everyone’s wish that we knew everything there is to know about birds, and in spite of the efforts of many people, there are still large gaps in our knowledge. In this book, which attempts to survey the larger landscape of research, there are thus gaps. Sometimes the book will be cruising along on a topic related to birds in the Northern Hemisphere, when suddenly, we shift to a somewhat different topic and birds of another part of earth. I don’t blame Pasquier for this; it’s just the contour of our knowledge.
He does deal with birds all over the world. I suspect for most readers this will be a plus; but if you are most interested in, to choose a random example, the boreal forest of the northern United States, you’ll have to skim and search a bit.
The book has a great index and bibliography, along with some nice line drawings by Margaret La Farge. Most of the book, however, is not illustrated. For anyone interested in birds and their lives, this book will be an interesting winter read.
News and Notes
The Day Before Winter
I’m giving a talk, “The Day Before Winter,” at the Sax-Zim Bog Welcome Center on Friday, December 20th! If you’re within driving distance of the Sax-Zim Bog in St. Louis County, Minnesota, join me on the day before the winter solstice for a talk guaranteed to get you warmed up for winter!
Learn how animals and plants prepare for the extremes of winter, including
- How one small group of birds managed to survive winter in the bog.
- Twelve kinds of trees and shrubs that thrive in the bog winter—you won’t believe #6!
- The seven successful strategies for responding to cold, wind, snow, ice, and drought.
- The three most painful mistakes Bigfoot made trying to survive winter in the bog.
- Are you struggling to survive winter in the bog? Try this!
Just in time for the shortest day of the year, learn ways to enhance your experience of the Sax-Zim Bog in winter.
Friday, December 20th, 2024 at noon at the Friends of Sax-Zim Bog Welcome Center. No admission fee or need to register. saxzim.org
Love this post. We have lots of owls where we live in the Central Okanagan and Dave's post reminds me of walks with my kids searching for where the "hoot" came from!
Thank you for all these interesting tidbits about Snowy Owls! I especially enjoyed learning about the airports that use falconers to prevent collisions between the Snowy Owls and aircraft. I have a very strong childhood memory of seeing a Snowy Owl on a beach on Long Island (where I grew up), back when my mom was a much more avid birder. Your comment that the hardest identification challenge is whether it is an owl or a bit of snowy ice really resonated with my memory of that day!
I wish I lived closer, because the topics for your talk at Sax-Zim Bog sound fascinating! A friend who lives in Duluth told me that Sax-Zim is quite popular in winter, so one of these days I'll have make a trip up in colder weather, instead of just a summertime roadtrip to the North Shore.