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What's Up Magazine

History in the Making

Jan 13, 2015 11:02AM ● By Cate Reynolds
Snowy owl irruptions can reach record numbers

By Lisa A. Lewis All photos courtesy of Allen Sklar and Project SNOWstorm

With its yellow, catlike eyes and beautiful white plumage, the snowy owl is truly a sight to behold, highly sought after by birdwatchers. But since these majestic birds live in the Arctic and are rarely seen in Maryland, birders may have resigned themselves to the fact that the only snowy owl they may ever see is Hedwig, Harry Potter’s companion—until now, that is. Last winter, Maryland experienced an invasion, or irruption, of snowy owls of epic proportions. In fact, that irruption—a phenomenon in which vast numbers of owls migrate much farther south than usual—was the largest irruption of snowy owls in the Northeast and Great Lakes region in four or five decades. Smaller irruptions typically occur every few years, but the magnitude of 2014’s irruption was extraordinary, making it a historic event and giving the birding community a reason to celebrate. With so many sightings, it was an ideal opportunity to see a snowy owl right here in Maryland—no Harry Potter movie required. Will this winter provide another glimpse of this magical bird?
“The last large irruption into Maryland was in the winter of 1949–50, but it’s hard to say how big it was,” says David Brinker, central region ecologist, Maryland Department of Natural Resources (DNR). “Information didn’t travel fast, and there was no Internet. Now, information is instantaneous, so it’s easier to ascertain the size of 2014’s winter’s irruption—and it’s huge.”

Why Snowy Owl Irruptions Occur

Although irruptions aren’t fully understood, scientists know that brown lemmings (a species of rodent), the preferred prey of snowy owls, play a role. According to Brinker, snowy owls have cyclical populations linked to prey abundance in their Arctic breeding grounds. When lemmings are abundant, the owls have highly productive breeding seasons, producing large clutches (eggs laid in nests) and fledging six to nine chicks for each nest. However, when lemmings are scarce, the owls may skip breeding that summer or move long distances to an area where sufficient prey for nesting is available.
Two summers ago, lemmings were abundant in parts of the Arctic, and the owls had an exceptional breeding season. When winter arrived, numerous young owls migrated south to wintering areas in Canada and along the Canadian/United States border. But young owls don’t compete well with adults and must find other areas to spend the winter. So they migrated farther south, causing the irruption. The owls will stay in Maryland until March or early April and then return to the Arctic.

Snowy Owl Sightings

According to the Cornell Lab of Ornithology, snowy owls are easily recognizable. These large owls are the heaviest owl species in North America, weighing between 3.5 and 6.5 pounds, with a wingspan of nearly five feet. Although snowy owls are white, they have black or brown markings on their body and wings. This is especially evident on females, in which markings may vary greatly among individual birds, and on young owls, which are heavily marked. Only adult males are virtually pure white.
Snowy owls prefer wide-open spaces, such as fields, shorelines, and airports, which are similar to their natural habitat, and like to perch in prominent places, such as fence posts and telephone poles. Several sightings have been reported in Maryland, including Hart-Miller Island, Assateague Island, the Bay Bridge, BWI, Sandy Point State Park, Quiet Waters Park, Gibson Island, Galesville, and Churchton, among others.

“Describing what it’s like to see a snowy owl is hard because you don’t expect to see one in Maryland,” says Bob Ringler, former president of the Maryland Ornithological Society and assistant editor of Maryland Birdlife magazine. “It’s such a rarity to see one this far south. I saw seven [last winter], and it’s a breathtaking experience. They’re spectacular birds.”

Tracking Snowy Owls

As if the irruption isn’t causing enough excitement, a tracking project is also adding to the fun. Brinker is participating in a regional collaborative project in which transmitters are placed on snowy owls throughout the Northeast to track and study their movements. In December, transmitters were applied to three owls: one in Maryland (the first snowy owl ever tagged in Maryland), one in Wisconsin, and one in Pennsylvania. Plans are underway to tag additional owls: two in Delaware and two more in Wisconsin. Information is posted on, so birders—and, hopefully, non-birders—can follow the tagged owls.
“Snowy owls are big, charismatic birds that look back at you with bright, yellow eyes,” Brinker says. “Typically, there are no snowy owls in Maryland. During a smaller irruption, there may be a few sightings. Last winter there were probably 20 to 25 owls here. An irruption may be a once-in-a-lifetime chance to see one of these magnificent birds in our area. It’s an amazing opportunity.”

Since last year’s irruption, birders throughout Maryland are on notice, binoculars seldom far from hands. One can hope there was an abundance of lemmings north of the border once again, so that the snowy owl might be seen south, closer to our homes.