The song of the American robin—large, friendly redbreast of suburban lawns and back yards—has long been said to herald the arrival of spring. For scientists who study long-term data, collected by community volunteers, the presence of the robin can signal much more, especially when it appears here in the winter.
Volunteers for the 2020 Audubon Christmas Bird Count observed 303 American robins during their survey in the Northeast Suburban area on Dec. 26. This area includes the communities of White Bear Lake, Dellwood, Hugo, Mahtomedi, Withrow, Stillwater, and Marine on St. Croix. The volunteers adjusted well to the restrictions of Covid-19; staying socially distanced and never sharing a vehicle with others outside their household or immediate social pod. Despite the new rules, 42 route-patrollers and 18 feeder-watchers were able to participate in the count this year.
The international Christmas Bird Count tradition is more than 100 years old. It was established as a less deadly alternative to Christmas bird hunts: once a staple of family Christmas gatherings. Over the decades it has evolved into one of the longest and most consistent collections of bird observation data, providing insight into the trends and behaviors among populations, which in turn provide clues about the state of the environment around us. The bird count is an entertaining way to spend a winter afternoon, somewhat like a neighborhood scavenger hunt. But the CBC is also a numbers game. Over his years of involvement in the count, Northeast Suburban count coordinator Jim Howitz has become well versed in the trends and statistics that prompt scientific questions about which populations are changing, and why.
One thing has been clear from the decades of amassed data: birds such as the American robin are changing where they spend their winters.
“When I was a kid, you never saw robins in winter,” said Howitz. “Their species name is ‘migratorius,’ so they’ve been migratory since the time of Linnaeus, but they stick around now. They use ornamental trees around yards, and during breeding season nest by your house and eat worms.”
This changing behavior is part of a much larger trend: robins are one among dozens of species that are pushing their winter range northward. Climate change is likely a large factor, Howitz said—as winters become milder, more birds are able to stay in place without expending energy on a long migration south. Waterfowl may even do so to avoid hunting seasons in the warmer areas of the U.S.
CBC volunteers also tallied a number of other species that aren’t usually found here in the winter months. Some sparrows, such as dark-eyed juncos, are known to stay through the winter, but on Dec. 26, counters observed song, chipping, and white-throated sparrows. Volunteers also found Wilson’s snipe, brown thrashers, and a varied thrush—a robin relative normally found in the Western U.S. Howitz said he expects it will be able to survive the winter, with the aid of ornamental fruit trees in the neighborhood.
While this diversity of species is exciting for volunteers to find, it is just as important to pay attention to what the counters don’t see. Over the long term, the CBC has recorded declining numbers of northern birds, which used to be seen in the Northeast Suburban area in abundance.
“We set the record for redpolls in 1977,” Howitz said. “We had more redpolls than anyplace else in North America, with 4,015 individuals. They come in these enormous flocks, and for a moment they can blot out the sky. Some years it’s just a handful, and this looks like a handful year. They may explode later in the year, sometimes you don’t see them at all and then in February and then you’re deluged with them. Winter is young.”
Some birders expected a winter irruption of northern finches this year, but the count volunteers saw no evening or pine grosbeaks as they hoped. The last pine grosbeak seen on the Northeast Suburban bird count was in 1989.
“Those were two northern finches we used to be able to count on, and they’re not here,” Howitz said. “We’re picking up new birds like robins, wrens, titmice, and losing birds that aren’t coming this far south, like redpolls.”
Birds from the southern reaches of the state, such as wild turkeys and red-bellied woodpeckers, are traveling further north than they ever have before. This year, the CBC included a Carolina wren and two tufted titmice—species Howitz said we can expect to see more of as the climate continues to warm.
“Practically everybody was happy with what we found; most people were finding one or two things they don’t normally find,” Howitz said.