We have been invaded from the north.  And this is a huge invasion — more than 2,000 Great Grey Owls and Northern Hawk Owls have recently swooped down into the states of Minnesota and Wisconsin from Canada.

The reason for this feathery border crossing?  Food.

The owls' favorite delicacy, meadow voles – which are small mouse-like rodents — seem to be scarce in Canada this winter. So these owls very wisely headed south, never even bothering to get passports or go through customs.

Over 2,000 Great Grey Owls have invaded this year, more than five times the highest number ever recorded.

And tagging along with them are 300 smaller Northern 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.

And devoted bird watchers from all over the U.S. are now flocking to Minnesota and Wisconsin to catch a glimpse of these magnificent creatures.

But there is also a problem facing these winged visitors from the Canadian wilderness. They are extremely low-flying hunters and, as a result, are extremely vulnerable when they swoop down over our crowded roadways.

About 250 of these magnificent birds have already been hit and killed by cars. Survivors of these tragic run-ins with vehicles are being nurtured back to health at the University of Minnesota's Raptor Center.

And come spring, these northern nomadic invaders will likely be long gone, leaving behind the lingering memory of their extremely haunting and enchanting invasion.