A snow-white owl focuses his sharp yellow eyes on the tundra grass in Nunavut, Canada. A chubby lemming darts by—but not fast enough. The owl swoops down, snatches the rodent in his talons, and soars back toward his nest. As he turns, a small black object glitters on his back in the sunlight. The shiny souvenir comes from his winter vacation in Illinois. It’s a $3,000 tracking device!
Did you see any snowy owls this winter? Snowy owls can normally be found only in chilly, Arctic spots—places where almost no people live. But this year, people in the upper American Midwest and Northeast saw the birds all over the place! They found snowy owls hanging out at airports. They spotted them in farm fields, on light poles, and along beaches. An unusually large snowy owl migration like this one is called an irruption. Snowy owl irruptions have happened only one other time in the last 100 years.
Here’s how an irruption works. Every three or four years, lemming populations grow quickly. For owls, that’s like a huge sale on bulk groceries. With so much extra food around, adult birds can afford to have lots of little owlets—as many as 14 at a time. The owl population explodes. The growing group of birds needs more space by winter. Sometimes there are so many owls that they move farther south to places where people live too.
That means people get a rare opportunity. They can keep better track of the birds. This winter, researchers caught many of the visiting owls. They attached tiny, lightweight GPS systems to the birds. The transmitters communicate with GPS satellites overhead. Once or twice a week, the information is sent to researchers in text messages. The messages show what the birds do minute by minute: Where do they go? How high do they fly? How fast?
When it comes to snowy owls, researchers still have many mysteries to solve. Snowy owls usually migrate south. But not every bird migrates every year, and they don’t always travel to the same places. Some years owls are found in Alaska. Other years they spend the winter in Canada or Russia. Researchers want to know: How far do these snow birds really migrate? Why do they go where they go? How many actually exist? And one question really has them scratching their heads: How do snowy owls know where to find lemmings each year?
