When biologist Dave Brinker saw two snowy owls on a small beach in Maryland, he was shocked. Brinker told colleagues, “Something huge is going on.” Brinker was speaking about a phenomenon that began right around Thanksgiving in the U.S. when bird watchers in Kentucky, Georgia, northern Florida, and even Bermuda reported sightings of the large bird of prey with its striking spotted markings. Data from past snowy owl migrations revealed an emerging situation the likes of which only happens once every fifty years. Brinker, along with his colleagues Scott Weidensaul and Norman Smith, responded swiftly. They stitched together a network of owl enthusiasts that included dozens of wildlife experts, scientists, organizations, and agencies across ten states. In less than two weeks, they had launched Project SNOWstorm, a collaborative research effort on “the historic snowy owl irruption of 2013-14.”
What is an irruption? According to the project’s website, it is the phenomenon whereby snowy owls make “unpredictable invasions” from the north for reasons that are not fully understood. Every few years an irruption occurs, but the one in the 2013-14 season was different in two ways: the number of owls and the distance they ventured south. Usually, their southern migration is only marked by a few sightings in the very northernmost states of the U.S.
Snowy owls are among the largest birds in North America. They start their lives far away from humans, on the vast expanses of the Arctic tundra. Even though documentation of snowy owl irruptions goes back 200 years, how the birds live their lives during their southern migration has remained a mystery. Until now, that is. Enter Project SNOWstorm, which raised $36,000 through indiegogo for custom-built snowy owl GPS transmitters. Brinker told NPR that the historic snowy owl irruption of 2013-14 has provided scientists with hitherto unknown information that will be used to better understand and protect the owls. Sightings provided volunteers the locations in which to set traps. Those places that the snowy owls like to linger while they are here are reminiscent of the Arctic tundra, open and flat areas such fields, marshes, and beaches. Twenty-two owls have been outfitted with GPS transmitters, and visitors can view their migration routes via interactive maps on the project’s site.
It is thought that the historic snowy owl irruption of 2013-14 points back to a population spike in lemmings, a staple of the snowy owl’s diet. Very capable predators, an adult will eat 3-5 lemmings per day. Last summer, the lemming population of northern Canada hit record levels, and owl parents-to-be feasted heartily. Biologist Francois Therrien took the photo at the top of this page. He counted 70 lemmings carcasses in this snowy owl’s nest. Before, Therrien had come across one, two, or three lemmings in a nest, so he was shocked to see 70 in one nest and 64 in another. The bumper crop in lemmings equated to larger snowy owl clutch sizes and fatter baby owls. These owlets leave the nest within two months, moving south onto other fare when the snow appears, which provides lemmings an excellent hiding place. Scientists also believe that the lemmings are responsible for the owls’ far-flung migration. The owl babies became powerful enough before they left the nest to fly as far as 3,000 miles in search of meals. However, Weidensaul specifies that they did not travel south because they were hungry. The ones that have been caught, he said, are healthy and fat. They seem to like the local food, and, according to the interactive maps, they have not started their flight back to the Arctic tundra quite yet.
By Donna Westlund