Snowy owl invasion a phenomenon of nature

Dimanche, Décembre 17, 2017

If we needed yet another example of the far-reaching connectivity of ecosystems, habitat and the species that dwell on this planet, the snowy owl comes through for us. This majestic resident of the open tundra of the high Arctic has been making appearances throughout the Lake Erie region over the past month, here on a temporary visa it chooses to use at somewhat irregular intervals. A large number of these Arctic residents have been identified in the Lake Erie region in recent weeks. Snowy owls have been spotted recently perched on rocky breakwalls along the lakeshore, in open fields near major highways, and along airport right-of-way areas. A naturally occurring chain of events — a phenomenon nonetheless — brings them to our stage.

“We’ve had an unusual number of reports from people who have seen snowy owls and been pleasantly surprised by the experience,” Bernie Place, from Wild Birds Unlimited on Monroe Street, said. “It’s definitely been a topic of discussion, because they are so distinct, and that is not a bird you see around here very often.” What is taking place is an irruption — a sudden and unexpected movement or surge that comes about when the natural ecological balances in one area are disturbed. In this case, an abundance of snowy owls in the far north. It started about a few weeks or a month ago, and it appears to be pretty widespread,” Place said. “We’ve heard that they’re being seen all the way from the Cleveland area to western Michigan, but it’s probably a wider region than that. It is a good-sized invasion.”

At least partial credit, or blame, goes to the lemmings. These small rodents of the Arctic tundra are the primary food source for snowy owls in the historic snowy owl range. When lemmings are plentiful, snowy owls will breed and raise young, and in years with a scarcity of lemmings, the owls often fail to nest. So it appears that in certain regions of the Arctic, lemmings were abundant this year, and the snowy owls took advantage of the bounty and produced a prolific crop of young owls. Now those young birds are on the move, searching for areas with significant food sources.

Mark Shieldcastle, the research director at the Black Swamp Bird Observatory along Lake Erie, said he believes the snowy owls we have seen so far this season are likely young-of-the-year birds, which he said indicates a “massive production year” for the species on the tundra.“This year may be one of the largest movements we have seen in this region,” Shieldcastle, a retired wildlife biologist, said. “It appears the movement is very broad scale across the eastern part of the country. It is going to be interesting to see how the winter unfolds and if an adult owl movement follows.”

Avian author and expert Kenn Kaufman said in a post on the Audubon website that snowy owls nest across the Arctic tundra of Canada, Alaska, Greenland, Scandinavia, and Russia. The world population estimate for snowy owls is around 300,000. Kaufman said the snowy owl numbers are subject to peaks and valleys, with their food supply as a primary factor in those fluctuations. Researchers with Project Snow Storm, which tracks the annual movements of snowy owls, contend the irruptions occur roughly every four years, coinciding with regional population explosions of lemmings. In the years of high numbers, some snowy owls surge south, some remain on the tundra throughout the winter, while others actually move north, hunting sea birds on the Arctic ice. Project Snow Storm studies indicate the irruption of snowy owls in the northern U.S. often could be more territorial in nature and is only occasionally due to a shortage of food in their home range.

“The researchers who study these irruptions actually report that the birds that come south during major irruptions are fatter and healthier than birds that wander during non-irruptive years,” Jerry Maynard of the Chocolay Raptor Center in Harvey, Mich., said in a report to the Michigan Department of Natural Resources. The eventual extent of the snowy owl movements is quite varied, with these birds of the Arctic reported as far south as Bermuda and Florida in the winter of 2013-14. This winter, there have been numerous snowy owl sightings along the New Jersey shoreline, and in Pennsylvania, Indiana, Michigan, Wisconsin and Illinois.

Snowy owls tend to prefer broad, flat and treeless areas which resemble their Arctic homeland. As the largest North American owl with a wing span of four to five feet and a weight of around 4-5 pounds, snowy owls present a significant bird-strike danger to aircraft. They have been a persistent problem around airports during past irruptions, with dozens trapped and relocated from airports near Detroit, Toronto and Windsor. Since they live in a region with little or no human activity, snowy owls are quite naïve around people and are easily approached, but biologists urge birders, photographers and the general public to keep their distance. If startled by too close an encounter, snowy owls can be chased into traffic or power lines — two main sources of injuries or deaths of these owls during an irruption event. Avian experts also stress that snowy owls should never be fed, since they can easily become habituated and associate people with a food source. Biologists say the snowy owls we are seeing across the Midwest are expected to return to the Arctic by March in preparation for the nesting season.

The Blade by outdoors editor Matt Markey - mmarkey@theblade.com or 419-724-6068.