North American birds are moving north and inland to escape climes that have heated up with global warming, according to a report released today that warns that some species risk being wiped out if climate change makes their natural habitats unlivable.

One-hundred-seventy-seven of the continent's 305 most common birds shifted their range farther north over the past four decades than in previous years, according to the Audobon Society's Christmas Bird Count. The annual survey is based on reports from 50,000 "citizen scientists" on birds they spot at more than 2,000 locations in the Americas over the last two weeks in December. It's been conducted for the past 109 years.

"It's sending us a very disturbing message," John Flicker, Audobon's president and CEO, said during a press teleconference today. "The impacts of global warming are being felt right now, here in North America, and have been taking a huge toll on ecological systems."

The birds' shifting movement — an average of 35 miles to the north, but more than 300 miles north for some species — is "quite a concern," because it tracks with rising temperatures, biologist Terry Root, a senior fellow at the Center for Environmental Science and Policy at Stanford University, said during the press conference. The Earth warmed up by 1.33 degrees Fahrenheit (0.7 degrees Celsius) from 1905 to 2005, according to the Intergovernmental Panel on Climate Change (IPCC). In North America, January is the month that has warmed up the most — by more than 5 degrees Fahrenheit over the past four decades, according to the Audobon report.

It's not clear exactly why the birds are shifting their range, but many birds typically breed in Alaska and Canada in the summer and fly south in the winter where they can find food and stay warm overnight, said Greg Butcher, the society's director for conservation. As temperatures have crept up, the birds may have found that they don’t need to go south to survive, he said.

The concern is that the cool climes will eventually become too hot, Root said. "Where are they going to be able to survive," she said, as it gets warmer and warmer?"

Image of Red-breasted Merganser, a bird species that has moved 317 miles north/USFWS, Dave Menke via Audobon Society