It's often said that spring arrives with the first Robin. Biologists would say robins aren't really the best indicator, based on migration habitats and that red-winged blackbirds might serve as a more accurate harbinger of a new season.
But as a warming climate shortens Maine's winters, bird species once rarely seen during the colder months now hang around for the entire year.
Just after sunup on a bitter early March morning, a chorus of birdsong that fills the air at Maine Audubon's Gilsland Farm.
Doug Hitchcox, a staff naturalist with Maine Audubon is pointing out male red-winged blackbirds that have come north to battle noisily for prime nesting spots.
And as climate change accelerated by fossil fuel pollution shortens Maine’s winters, Hitchcox says they’re arriving earlier and staying later.
"It was always, you know, kind of the first week of March, red-winged black birds would come back then," Hitchcox said. "And then, a couple years later, it was one of the last weeks of February. Then couple years later, mid February."
Finally, two years ago birders reported seeing red-winged blackbirds every single week of the year, according to Hitchcox.
"These are still a small number of birds, but it's definitely, I think, kind of an early indicator of some of the changes that are going on here," he said.
Maine's notoriously tough winters are the time of the year warming fastest. According to the Maine Climate Council, the coldest season is 5 degrees warmer and two weeks shorter than it was a century ago.
Across the country, common bird species are moving along with the changes. The U.S. Environmental Protection Agency found that between 1966 and 2013, hundreds of widespread species moved the center of their winter range 40 miles north.
Those include striking Eastern bluebirds, once seen as a sign of spring, Hitchcox said.
Those are "another species that just went from rare in the winter to now common and abundant, especially in the southern half of the state," he said.
Winter volunteer sightings of the bright birds skyrocketed from just a handful 30 years ago to more than 1,100 in 2023.
Red-bellied woodpeckers, an historically southern species whose sightings in Maine once generated among birders buzz are now commonplace year round. And Hitchcox said he often gets midwinter reports about Carolina wren from birders misled by field guides that are now out of date.
"Until the 1980s or so Carolina wrens were barely into southern New England. So a lot of people see an old map like that, and just think, 'oh, this bird. It shouldn't be here,' but that's really what the change has been."
While some birds appear to be thriving, John Garrett from the Cornell Lab of Ornithology and others are sounding alarms about the threats made worse by climate change, such as habitat loss, food scarcity and pollution.
"We've lost 3 billion birds since 1970," Garrett said. "The lab's whole mantra right now is; how have we lost this many birds? And why? And climate is definitely a big part of it."
And warmer winters aren't the only drivers northward bird expansion. Red-bellied woodpeckers are attracted to regrown New England forests, Garrett says. And bluebirds were helped by a successful birdhouse building program.
"What's really tricky is it's often really hard to disentangle what's climate change versus all of these other things that humans do that affect bird populations," he said.
Back in Falmouth, Hitchcox said that as new birds move in, old familiar ones are fading out. The Boreal Chickadee, for example, once common as far south as Hancock and Washington counties, is now confined to far northern Maine.
"And the tough thing is, like there's only so far north you can go, so that's going to be the the scary thing for these more site specific birds that that lose their their regions," he said.
