The winter of 2017-2018 has brought an influx of snowy owls to some parts of the U.S., with the Arctic raptors showing up at least as far south as Missouri and South Carolina. This has understandably caused a stir in many places, with people clamoring to catch a rare glimpse of the birds so far from their traditional habitat.

This phenomenon, known as an "irruption," happens roughly every four years, according to Arctic Now. It's triggered by a periodic lemming boom in northern Canada, where the abundance of food allows snowy owls to raise large clutches of up to 11 eggs. This results in a population boom for the owls, some of which must then fly unusually far south after the breeding season. They'll fly back north by spring, however, and seem to be well-equipped for the adventure.

Prior to this winter, a record-setting irruption of snowy owls also captivated many photographers across the U.S. in late 2013 and early 2014. That included Larry Keller, who lives in south-central Pennsylvania where the snowy owls began to arrive in November 2013, and who took the photos on this page.

snowy owl on ground

"I saw my first snowy owl about 40 years ago and this is the first time I’ve seen any since," Keller told MNN in March 2014. "There have been a few in Pennsylvania in past years, but nothing like this year. We have at least six snowy owls in Lancaster County this year and all six are still here in early March."

Because of their rarity in such high numbers on the region, the birding and photography communities snapped up the chance to see these birds in the wild.

snowy owl on fence

"Birders and photographers have come from all over the East Coast to see and photograph these birds," Keller said in 2014. "Every day of the week you’ll find a dozen or so cars along the road and a group of birders and photographers watching the owls, which are mostly sitting in a field sleeping. I go out before sunrise and photograph and watch the owls till I see they are going to roost for the day, usually an hour or so after sunrise."

snowy owl and crow

Keller, a retiree who photographs birds and wildlife on a daily basis, has been one of the more avid watchers, and he has captured beautiful portraits and interesting behaviors with his camera. "My most memorable moment photographing these owls has to be the morning I had two owls fighting or playing right in front of my camera. I was focused on one light-colored (a male) snowy when out of no where a darker owl (a female) flew into my frame and jumped on the owl I was photographing. I had no idea that owl was even in the area," he said.

snowy owl look

It isn't just people in the general vicinity who have enjoyed the irruption. Fans of Keller's photography have been experiencing it through his images, and loving everything he posts on Flickr.

snowy owl with duck

Keller also has some wise words for those who want to view the owls in person: "Please don’t stress these birds by trying to get closer. Snowy owls don’t seem to be afraid of people, but I don’t think they want to be friends either, and trying to get that close photo will only flush them and stress them. Watch from a distance, stay still, and be quiet. I would like everyone viewing or photographing these owls or any wildlife to remember these are wild birds and animals. Though many of my images look like I was very close is a little misleading. Most of my images were taken from 80 to 100 yards or more."

snowy owl yawn

"A snowy in flight is so beautiful that no words can describe it — every time I see one in flight my heart races. To think that these birds traveled the distance from the Arctic to spend the winter here is just incredible, and now they have the flight back home."

snowy owl flight

snowy owl against blue sky

Editor's note: This story has been updated since it was first published in March 2014.

Jaymi Heimbuch ( @jaymiheimbuch ) focuses on wildlife conservation and animal news from her home base in San Francisco.

9 photos celebrating the snowy owl irruption
Snowy owls are traveling unusually far south this winter, as they also did in 2014, when a photographer caught these endearing images.