Out & About: A snowy invasion

As snow falls, a young Snowy Owl sits on a shed roof in Lancaster County-over 1,000 miles south of its normal range.

We’ve been invaded. To date, over 20 counties in Pennsylvania and states as far south as Florida have also been affected. One of the visitors even found its way to the island of Bermuda. Not to worry though, the guests are not aliens from a faraway galaxy. They’re beautiful birds from the arctic-quiet, magnificent, showy and snowy! The guests from up north are Snowy Owls.

Snowy owls are large, white birds of prey. Immature birds have black barring on their bodies and mature birds are almost pure white. They have piercing yellow eyes and a wingspan of nearly five feet. Mature birds may weigh up to six pounds. They are majestic-looking, almost magical. Maybe this is why Harry Potter chose one as his pet, called Hedwig!

A Snowy owl’s normal range is the arctic tundra, and can be found in Alaska, Canada and the northern countries of Europe and Asia, as well. When they wander outside their normal range in high numbers, biologists refer to these movements as irruptions. This year’s irruption (winter of 2013-14) is producing historic numbers of sightings in Eastern Canada and the United States, mainly the northeast and upper mid-west states. But why are all these impressive, ghost-like birds showing up on the beaches of the east coast, major airports and farm fields? Scientists still may not have all the answers to that question yet, but some evidence points to the availability of food.

In the arctic, snowy owls feeds mainly on lemmings, a small rodent whose numbers are cyclic, higher in some years, and lower in others. Due to the long summer days in the arctic, the birds are very active during daylight hours (diurnal). Biologists have determined the population of Snowy owls is directly related to the population of lemmings, on their breeding grounds. When lemming populations are high, female Snowy owls lay more eggs. As lemming populations decrease, Snowy owls produce fewer chicks, since food (lemmings) may not be as abundant. Snowy owls will also prey on waterfowl, shorebirds and other small animals as well. Many of these visiting birds that are being reported are identified as juveniles, most likely hatched from last season’s breeding season. When news spread about this amazing irruption, people assumed that these young birds were starving, and had to move south to find food to survive. But in fact, biologists have documented the direct opposite. Researchers feel that a high lemming population last year led to an extremely productive breeding season, especially in northern Quebec. Snowy owls from many areas of the Canadian Arctic may have moved in to this area to take advantage of the abundance of food, stayed, and raised families. Lots of food equaled lots of new Snowy owls. When winter struck early in the tundra, all these young birds spread their wings and began heading south (and west and east). They were not starving. In fact, the Snowy owls that have been tagged were found to be in great shape; heavier, and having more fat reserves and muscle than ones from lower years. This is why we’re getting the privilege of seeing Snowy owls in Pennsylvania!

If you get the rare chance to see one of these striking birds, try to enjoy them from a distance. Who wouldn’t want to stop and look at a large, white owl sitting on a fence post in the middle of the day? But remember, because these birds live far from humans they may not show signs of being afraid of people, and therefore, not fly away at first look. However, it’s easy to practice one simple outdoor ethic when observing these birds, or any other wildlife. Don’t chase or harass the critter, which can be harmful to the animal in the long term, and may prevent others from enjoying this white wonder from the north! For more information on this historic Snowy owl irruption and how you can help, log on to www.projectSNOWstorm.com.

Many thanks to Scott Weidensaul for contributing valuable background information for this article.