North America's wonky winter forced its different bird populations to flock much farther afield this year as Arctic species moved south and southern watefowl showed up in ice-free Canada much earlier in the year.
Snowy owls from the Arctic and tundra swans, which normally winter in the southern U.S., as far south as Florida, were among the birds reported in unusually high numbers in Canada during this year's annual Great Backyard Bird Count.
Four times as many snowy owls and nearly 17 times more tundra swans were reported by Canadian participants this year than last year, said Bird Studies Canada this week.
The group partners with the U.S.-based Cornell Lab of Ornithology and the National Audubon Society of the U.S. to coordinate the annual count, which ran across Canada and the U.S. from Feb. 17 to 20.
Scientists think the snowy owls moved further south than usual this winter due to a shortage of food such as lemmings. They were spotted in much greater number in the central U.S. plains and the Pacific Northwest as well.
Meanwhile, the jump in waterfowl such as tundra swans, canvasbacks, redheads and sandhill cranes was likely due to the warm winter weather and lack of ice, Bird Studies Canada said. Many of these species migrate to the Arctic area for summer breeding but don't usually head there until much later in the year.
Snowy owls and waterfowl weren't the ones that showed up in record numbers this year – so did participating Canadians.
They submitted a total of 9,800 bird checklists – an "impressive increase" from last year's record of 7,500.
Overall across North America, 104,000 people participated, counting 17.4 million birds from 623 species.
The organizers of the count consider this year's to be "the most unusual winter for birds in the count's 15-year history," largely due to the unusually warm weather that pushed many species further north than usual for the season.
The Great Backyard Bird Count is among several ongoing citizen-science projects that rely on ordinary birders rather than just professionally-trained scientists to gather data over huge geographic areas about where bird species are at certain times of year. The information is compiled to track trends in the movements and populations of different bird species.