Snowy Owl Irruption

By Ruth Ann Grissom

February 7, 2018

In the days before the Uwharries’ first snowfall in early December, J.D. Bricken, manager of the Pee Dee National Wildlife Refuge, received a call from a neighbor concerned about an owl hanging out on the ground around his chicken house. Bricken is accustomed to picking up injured raptors, but this would prove to be a memorable call.

From a distance, the pale bird appeared to be a barn owl, but as Bricken approached it, he was awestruck by its size, the whiteness of its feathers and its piercing yellow eyes. Instead of using a net, which can tangle in their wings, he tossed a large shirt just as the bird started to fly. Bricken quickly realized he had captured his first snowy owl.

These majestic birds are denizens of the Arctic tundra. While most bird species exhibit a trait known as site fidelity, snowy owls are itinerant. In winter, they often retreat to ice floes to hunt sea ducks. During breeding season, they somehow locate areas with explosive populations of lemmings, a small rodent whose numbers experience dramatic peaks and troughs on a four-year cycle. In lean years, up to three chicks might fledge from a nest, but when lemmings are especially abundant, that number can double or triple.

Come winter, many of those well-fed juveniles head south, like insouciant college kids on spring break. This movement is known as an irruption, an irregular and somewhat unpredictable migration that occurs among pine siskins and several other bird species. When snowy owls come south, they gravitate to habitats that resemble the treeless tundra – sand dunes, fields and airports. Many are plump and healthy on arrival, but the mortality rate is high for any juvenile raptor, and these owls have the additional burden of hunting in unfamiliar surroundings. They suffer injuries typical of other raptor species – electrocution, poisoning and collisions with cars and planes.

Bricken arranged to have the Pee Dee owl transported to the Carolina Raptor Center (www.carolinaraptorcenter.org) just north of Charlotte. From its humble beginnings in 1975, CRC has become one of the nation’s premier rehabilitation centers for birds of prey. This was the first snowy owl they had ever treated. The Pee Dee owl had a bruised wing and she was terribly thin, perhaps because the injury made it difficult for her to hunt. A snowy owl this far south, especially one in her weakened condition, is also susceptible to aspergillosis, an airborne fungus that attacks the lungs. Despite heroic measures from CRC staff, including their first cross-species blood transfusion, the Pee Dee owl did not survive. A necropsy later confirmed her lungs had lesions consistent with aspergillosis.

Within days, to everyone’s amazement, another snowy owl was brought to CRC. This one was captured at the Piedmont Triad International Airport. He was also thin, and his brilliant white feathers were covered with mites, but he otherwise seemed healthy. Under their care, he put on weight and grew stronger, making impressive sweeps the length of his flight cage (https://crc-rehab-blog.tumblr.com/post/169314451495/snowy-owl-21191-is-doing-great-in-his-flight).

As the logistics for his release were being finalized, he suddenly stopped eating. CRC staff hoped this was due to nothing more than the stress of being confined and decided it was best to go ahead and release him as soon as possible, especially given the constant threat of aspergillosis. I was allowed to observe CRC’s experienced rehab team perform his final examination. They splinted his tail feathers with a tongue depressor and wrapped them in heavy paper then padded his wrists with bumpers to protect them from damage while he was confined to the kennel. They gave him fluids and fed him hunks of mice and rats. He seemed alert and restless. It was bittersweet for the staff, but he seemed ready to go.

After considering locations in Minnesota and New Hampshire, they had settled on Vermont since it’s likely on the flight path that brought him south. He arrived in style, on a private plane owned by couple from Rock Hill, S.C. He was greeted by officials with the Vermont Institute for Natural Sciences. They drove him to Dead Creek Refuge and banded him before his release. According to Michele Houck at CRC, “He flew well and another snowy showed up to welcome him.”

A band can provide some basic information if a bird is ever captured again, but cutting edge technology is now being used to learn much more about these peripatetic raptors. A group of scientists formed Project SNOWstorm (www.projectsnowstorm.org) in the midst of the spectacular irruption of 2013-14. Perhaps the largest irruption since the 1920s, it brought snowy owls as far south as Florida and Bermuda. Since then, dozens of birds have been fitted with solar-powered GPS transmitters that pinpoint locations in three dimensions and update at intervals as short as 30 seconds. When the owls are out of cell phone range, their movements go dark, but the devices keep recording. They have the capacity to store more than 12 years of data, which is automatically downloaded when the birds dip back into an area with coverage.

This effort takes us on a virtual journey to the desolate haunts of the snowy owl. We imagine the summers of continuous daylight and winters of endless night. We marvel at their ability to locate and capture not only small rodents but also large sea ducks. So often, science brings us closer to wonder.

What are the chances of a snowy owl being found on the edge of the Uwharries? In some respects, the region is also terra incognita. There’s a lot of open space, with few people birding on a regular basis. Unlike an owl that turns up at an airport, the Pee Dee owl could have easily gone unnoticed. How many others have graced those stubbled fields and crystal skies? Where do they come from? What do they hunt? How long do they stay? Do they ever return? Thanks to the CRC and Project SNOWstorm, perhaps we’ll someday be able to answer the many questions that remain about the intriguing existence of the snowy owl.

For more on snowy owls, go to http://www.audubon.org/magazine/march-april-2014/with-so-many-snowies-study-scientists-are or https://www.npr.org/2014/03/11/288762497/the-great-snowy-owl-invasion.

See the owl released!

http://www.wcax.com/content/news/Rehabbed-snowy-owl-catches-flight-to-Vermont-for-release-473001453.html