Owls are airborne invaders-powerful in flight, intimidating in repose and perching in numbers far beyond anything anyone remembers in the woods of northern Minnesota and Wisconsin. Among those staring back is avid bird-watcher Sharon Stiteler, the queen of BirdChick. com. "Oh, I love owls," she says. And there are plenty of them to love-more than 2,000 Great Grey owls and Northern Hawk owls have swooped down from Canada. Stiteler braves subzero temperatures, learning the language and trying to get as close as she can.
The owls’favorite delicacy, meadow voles-small mouse-like rodents-are scarce in Canada this winter. So the owls, wisely, headed south. "They will actually extend their talons forward and crash through the snow, and capture the voles without ever seeing them!" exclaims Carrol Henderson with the Minnesota Department of Natural Resources. Over 2,000Great Greys have come this year, more than five times the highest number ever recorded. Tagging along are 300 smaller Hawk owls. "I don't think anybody right now is thinking that we're going to see anything like this again in our lifetime," says wildlife biologist Jim Lind.
But there is a problem facing these visitors from the northern wilderness. They are low-flying hunters and, as a result, are very vulnerable when they swoop down over roadways. About 250 have already been hit and killed by cars. Survivors are nurtured back to health at the University of Minnesota's raptor center.
No stranger to the cold, avian researcher Dave Grosshuesh captures and bands many owls, studying their movement, age and overall health. Not far away, Sharon Stiteler shivers on her own. But birders from as far away as New York and California often migrate here to marvel. Is all this for the birds？ "Some people spend oodles on shoes; some people spend oodles on their nails," says Stiteler. "I spend oodles of time and money on birds!" Still, come spring these northern nomads will likely be gone, leaving behind the lingering memory of their haunting stares.
From the passage we can learn that _______.

A. Owls are native birds of the United Sates.
B. Mouse-like rodents like to eat meadow voles.
C. Fewer smaller Hawk owls came this year.
D. The number of Great Greys coming this year is very impressive.