FORT WAYNE – They don’t have green cards or even temporary visas, but observers all across the northern United States are reporting an influx of Canadians.

Be on the lookout – they’re known for their shocking white feather coats, huge gold eyes and an appetite for small mammals.

Whether you call it an invasion or an irruption, snowy owls are moving unto the United States from Canada in search of food and territory, including Indiana.

“This happens every six or seven years,” said Bob Walton, a volunteer with Soarin’ Hawk Raptor Rehab, which rescues injured and orphaned birds of prey such as owls. “This invasion’s not as heavy as some years have been in the past.”

Walton said there have been 15-20 snowy owl reports in Indiana, with the furthest south being sightings near Pierceton. Two sightings were reported in early December near Harlan.

Snowy owls can be up to 2 feet tall and weigh up to 6 pounds, though the ones here are much smaller – mostly young males.

“They’re an animal with a cyclic population that increases and decreases – it goes up and down with the prey animals, the lemmings and things like that,” said Gary Tieben, president of the Stockbridge Audubon Society. “In the years their population goes up there’s plenty of food, so the snowy owls are able to keep all their babies alive. But when you get a certain number of those small animals, it’s more than the habitat can take … and (the prey) population will crash.”

That leaves a big predator population with little food. So the snowys move south where the pastures are literally greener.

“That’s what’s happening,” Tieben said. “We have an invasion here.”

But it’s a temporary one. When spring returns and hunting is easier in the tundra and boreal forests the snowys prefer, they’ll move back north.

At least, some of them will.

“Most will not go north because they just won’t make it,” Tieben said. “They really don’t have any experience with people, no experience with cars and trucks. They’ll swoop low over the road and get hit by cars when they do that.”

In Tieben’s view, the prospect for these magnificent visitors is grim.

“Most will die in a ditch or back in the woods,” he said.

Not everyone agrees.

While it’s true they are younger birds that could not establish a territory farther north, and they’re unfamiliar with some of the hazards here, there is more food here, said IPFW biology professor Bruce Kingsbury. When they all disappear in the spring, it’s not necessarily because they’ve died but because they’ve gone home.

“I’m more of an optimist,” Kingsbury said.

But he also has reason to be optimistic – like many other species, snowys are incredible survivors, to the point that they can control how many eggs they lay so that when food is scarce they produce fewer young. And many species travel to where food is more abundant when needed.

“With a lot of arctic wildlife, especially birds, they will shift where they spend their time,” Kingsbury said. “I would view this invasion as temporary.”

There are other reasons to head back to the tundra in the spring besides preferred habitat – mainly competition from a species already here. Snowys are similar in size and habit to great horned owls, which are native and will compete with them for food.

And that food isn’t always just rats and mice.

Pat Funnell, a veterinarian who volunteers with Soarin’ Hawk Raptor Rehab, said snowys will prey on pets.

“The same as a great horned owl, they’ll take small dogs or cats, certainly,” Funnell said. “They are great predators.”

Hundreds of sightings have been reported across the United States, with one as far south as Oklahoma, though most have been in the Great Lakes states, the Northeast and the far Northwest.

But there are likely more snowys here than reports indicate, Walton said, because birds tend to be in wild or rural areas where they are not easily seen, or because people like himself don’t report them until well after the fact in an attempt to protect the birds from well-meaning people who unknowingly harass the birds trying to see them.

Walton said that when word got out about the sightings near Harlan, people were driving across farmers’ fields trying to get close to them.

“That’s why I don’t report my sightings right away,” he said.

The draw of the birds, however, is understandable.

“They are just gorgeous, and their eyes are just more bright gold than you’d ever guess,” Funnell said.

“They are spectacular,” IPFW’s Kingsbury said. “It’s a combination of several things. Their color, their size is unusual. And I think owls are sort of mystical in their appearance … When you see or hear them, it still reminds us of the wilder side of things.”

dstockman@jg.net