On a table in the Raptor Center treatment room, a great horned owl is wrapped in a towel, enduring an examination. It got tangled up in a fishing hook and line. Veterinary technician Greg Hansen says someone found it along a riverbank.
"They untangled it and got the fishing hook out; it had flown up into a tree, but that was about as far as it could get," Hansen said.
As Hansen checks the bird's wounds, a volunteer with heavy leather gloves holds the bird on the table.
The bird is cheeping loudly, but Hansen declines to translate: "I don't know if I could say that on radio," he said with a smile.
At another table, Dr. Luis Cruz is checking a snowy owl. This poor bird had three broken bones when it was brought to the Center at the end of October.
He's about the size of a newborn human, maybe 2 feet tall, but he only weighs about 3 pounds. All those white feathers, and very light bones, and the eyes -- yellow, bright, and penetrating, almost as if he's trying to tell us something.
"This is the broken wing," Cruz said. "This is called physical therapy. Basically what I'm doing is extending the wing to test how far it reaches. He really doesn't like this too much, but the wing extension is somewhat limited but it's not too bad, and it doesn't seem too painful."
Cruz thinks the bird might have been hit by a train.
He set the bones in several stages, using metal rods inside and outside the wing. He gave the owl antibiotics and pain medications. Bird bones heal quickly, and Dr. Cruz has now taken all the metal rods out.
They won't release this snowy owl until spring. He needs to heal, he needs to recover his muscle strength, and he needs to grow feathers back where they plucked him to do the surgery.
"Those feathers have not come back, so we cannot even house her outside because she has a bare spot," said Cruz.
Cruz keeps calling the bird a "she," even though it's probably a "he." Females are larger than males, and this bird looks really big to Dr. Cruz, whose home is in Costa Rica.
Most of the snowy owls that have been brought to the Raptor Center this winter are starving. Sometimes they can be saved with blood transfusions, drugs and fluids. But the doctors here are experienced enough to know when an owl is too far gone, and in that case they euthanize the animal.
The abundance of snowy owls in Minnesota this year isn't a surprise. Their home is in the arctic, and normally they stay in northern Canada, even in the winter.
But clinic manager Lori Arent says there's been a pattern, every seven or eight years, of a lot of young birds flying south in search of food -- apparently because of a collapse in the lemming population up north. But this year, she's not sure.
The last two times numbers were high, the Raptor Center treated about two dozen snowy owls. This year they've seen fewer than half that number, only nine birds. And the usual explanation doesn't quite fit either.
"Because they were saying that the lemming population in southern Canada is very good this year," Arent said. "So if that's the case, why are some of these youngsters coming farther south? We don't know."
A new patient is on the exam table -- it's a bald eagle. It was found near Bemidji, and the veterinarians are still trying to figure out what's wrong with it. An x-ray showed trauma, but they're testing the bird for lead poisoning.
"Even if the bird was hit by a car, sometimes it'll come in with a broken wing but also have lead toxicity," Arent said. "So the question is, was it hit by a car because it was suffering from lead and was a little bit weaker, or is that just an incidental finding?"
If the bird does have lead poisoning, it can be treated.
It's an amazing amount of trouble to go to for a bunch of birds. But Lori Arent says it's not just for the birds.
The Raptor Center uses the information it gleans from its patients to track diseases like avian influenza and West Nile virus, a disease that killed 37 people this year.
"We certainly see it in the birds here too, so we know when it hits our area, because we see that first bird come it with it," Arent said. "So it's a warning -- be careful, the mosquitoes that carry this virus are out there, do what you need to protect yourself, too."
They're developing a database that will summarize information from bird rehabilitation centers around the country.
And they'll be puzzling over what's bringing those young snowy owls down south, when there are plenty of lemmings in Canada.