Did you know that Iowa is being invaded this winter? And, we’re not alone. The invasion is happening all of the Northeast section of North America. But unless you’re a mouse, there’s no reason to be alarmed.
Snowy Owls are irrupting south in huge numbers. These magnificent birds started showing up in October, and more and more are being seen as winter progresses. I’ll get back to the invasion, but I want to explain why these owls are so incredible.
Snowy Owls are BIG! They are 20 - 28 inches tall, and have a wingspan of 50 - 58 inches. This is as big or bigger than our Great Horned Owls. Snowys are also our heaviest owl, weighing 3 ½ - 6 ½ pounds, a full pound heavier than Great Horned Owls in all size ranges.
Snowy Owls are very appropriately named. These ghostlike birds can be almost entirely white. They all have rounded heads with no ear tufts. Their faes have cat-like bright yellow eyes, accented by black eyelid edges. Black beaks complete their unmistakable faces. Their feet are heavily feathered, black talons.
Adult male Snoweys are the whitest, with little or no dark markings. Adult females (which are larger) will have varying amounts of black flecks in their plumage. They may look more “salt and pepper” than the white males. Juvinile Snowys are the most heavily marked with black flecks and bars, but it’s hard to tell juviniles from mature females.
Snowy Owls live year round in one of the world’s most inhospitable regions. Their normal range is on the arctic tundra, above the
Arctic Circle north of the tree line. They “circle the globe” in this desolate, frigid environment, being found in both North America and Eurasia.
Because they live in such remote, hostile places, there’s a lot we don’t know about Snowy Owls. We do know that they nest on the ground. (Kind of necessary where there aren’t any trees.) The female makes a shallow scrape on a mound or boulder that affords a good view of the surrounding area. She lays 3-11 eggs, depending on how plentiful the food supply is. In lean years, a pair may not nest at all.
She broods the eggs and young while the male guards their territory and feeds her and the nestlings. They don’t have a lot of predators to worry about, but foxes and other raptors can be a danger. They will both aggressively defend their territory by swooping and diving at any intruder. They may also use a “fake injury” defense by dragging one wing on the ground to lure a predator away. Snow Geese often nest near Snowy Owls to take advantage of the protection they provide.
A Snowy Owl’s main food source is lemmings. Adult Snowys eat 7-12 lemmings a day. One Snowy can consume more than 1,600 lemmings a year. They will cache food when the hunting is good, storing food for leaner times. Most owls will only consume food as soon as they’ve killed it, but they don’t live in the Snowy’s harsh world.
Snowys use a sit and wait style of hunting. They will swoop from a low perch to capture prey from the ground or snatch it from the air. Although their main food source is small rodents, they are aggressive and opportunistic hunters. Other birds’ eggs and young, ducks, geese and carrion may be included in their diet. Fish can be snatched from the water’s surface in their powerful claws.
Our resident owls are pretty strictly nocturnal hunters. Snowy Owls hunt both day and night. Twenty-four hours of daylight and 24 hours of darkness in the polar region has made them very versatile hunters.
Snowy Owls have both incredible hearing and sight. They can hear movements under the snow, and dive in to capture prey. They have typical owls’ silent flight. These attributes, plus thick plumage, feathered feet and camouflage coloring all make the Snow Owl well adapted to life north of the Arctic Circle.
So that’s what we’ve know about the regal Snowy Owl until just recently. During the winter of 2011/2012 we had a large irruption of Snowys into the U.S. In the winter of 2013/2014 we had a huge irruption. Modern tracking devices have expanded our knowledge about Snowy Owls’ behavior and movements. We’ve also learned how little we really know about these owls.
Some Snowy Owls actually migrate north in the winter out onto ice flows. Since no one’s been brave enough to go check on them, we have to assume that they’re hunting and surviving on Arctic Sea ducks. Snowys are very nomadic. They wander thousands of miles over their frozen world without ever heading south.
One of the most intriguing and baffling discoveries, is that Snowys from all over the millions of square miles of tundra seem to know where the lemming populations are the largest. Where a lemming population explodes, the Snowys will be there to nest in huge numbers. How do they know where to be?
Ok, back to our invasion. Snowy Owls have historically irrupted into the U.S. in sizable numbers every 3-5 years. For many years it’s been thought that these irruptions were caused by declines in food supplies. Recent research suggests just the opposite. When prey is plentiful, Snowys have great nesting success (remember the 3-11 eggs) so there are much greater numbers of Snowys to spread out in the winter.
This winter is already a huge invasion. The latest update from 12-22-17 has 129 Snowy Owls reported in Iowa. Several of these have been very close around Mason City and Ventura. I’m sure there are a lot more here, because lots of folks don’t know where or how to report a sighting.
If you’re out in the country why not look for Snowy Owls. Scan flat, snowy areas (lots of those around!). Look for “lumps” or dirty patches on the ground. And check low perches. You won’t find Snowys in the trees, they like to perch on fence posts, hay bales, low buildings and grain bins. Anything that looks like a white bucket in a field might be a Snowy!
Just a note on Snowy Owl etiquette. If you see one, don’t approach it. Like many northern birds, they aren’t familiar with people. They are low flyers and if you flush it, it’s in danger of being hit by cars. So, observe from a distance, please.
On a very personal note, I’d like to share my most memorable sightings. Many, (make that many, many) years ago, when I was a UPS driver, I saw my first Snowy Owl while delivering rural routes north and west of Forest City. It was right at dusk, and there were there of them. I was just a beginning birder, but I still knew it was an awesome sight!
In 2009, my husband and I explored Alaska all the way to the Arctic Ocean. I was lucky enough to see a Snowy Owl on the tundra. It was an incredible highlight to an incredible trip!
If you would like to track or report Snowy Owl Sightings, go to http://www.iowabirds.org. Snowy Owl status was changed from least concern to vulnerable to extinction in 2017.
In case you wondered: Harry Potter’s owl “Hedwig” is a female Snowy Owl!
Birds can have trouble finding the grit they need when the ground is covered with ice and snow. Grit can be mixed with their seed or put in a jelly feeder with a roof on it. It’s amazing how popular this non-food offering can be.
A heated birdbath or an addon heater to your existing bath is another way to enjoy the birds in the winter. Birds who don’t come to our feeders normally will come to open water in the winter.
Enjoy Your Birds!
Ellen S. Montgomery