HOUGHTON — Each December, as Christmas approaches and winter weather returns, birders across North and South America ready themselves for the annual Christmas Bird Count.

The purpose of the count is to collect bird population data in order to better understand winter bird movements, assess bird population health, and guide conservation action.

The count is organized by the National Audubon Society, a nonprofit environmental group with the mission of protecting bird species and their habitat.

But while Audubon sponsors the event and compiles the data, the count itself is conducted through a massive citizen science effort, with the participation of tens of thousands of volunteers throughout the United States, Canada, Latin America, the Caribbean, and South America.

In the U.P., the Copper Country Audubon chapter holds bird counts in Eagle Harbor, Houghton, Keweenaw Bay, and Marquette.

Nancy Auer is the “compiler” in charge of coordinating the Christmas Bird Count in Houghton County, and compiling the data. On Saturday, Dec. 18, Auer and other volunteers will be counting birds in a designated area that encompasses Houghton, Hancock, Portage Lake, and South Entry.

“We do what we call ‘circle counts’, where a specific point in each county is chosen and then a 15-mile diameter circle is drawn,” Auer explained during a phone interview on Thursday morning. “We break up into teams and each group does part of the circle.”

During the 24-hour bird count period, some volunteers simply note the birds that visit their feeders, while others venture further afield and spend the entire day observing birds in the wilderness. Some volunteers even wake up early to go “owling,” or listening for owl calls.

This year will be the 122nd Christmas Bird Count, and the 45th consecutive year that the count has been carried out in Houghton. Auer, who has served as the area compiler for 17 years, said that normally, 15 to 20 volunteers participate in the Houghton count.

“We have people who have done one area for years and years. It actually is helpful because they know where to look in that area for birds,” she said. “We try to put new people or visitors with people that have a lot of experience in each of the sections so that we get good coverage.”

While volunteers count all of the bird species that they observe, they relish the chance to spot unusual species.

“We’re always on the hunt for rare birds,” said Auer. “It’s always fun to hear that there’s still a loon around or some unusual species of water bird.”

After the birds are counted, Auer compiles the data and shares it with Audubon.

“People at Audubon plot all this data from everywhere and they can track species abundance, and presence/absence. It gives a general idea of who’s out there and how the birds are doing,” she explained.

Over the past century, this data has been valuable to scientists, conservations, and government agencies. It has enabled researchers to study long-term bird population trends across the Americas.

During the 2020 count, birders covered 2,459 circles, including 1,842 in the U.S. Volunteers tallied 664 different bird species in the U.S., and 2,355 species worldwide.

Still, bird species across the Americas are under threat and many bird populations are in decline. A 2019 study found that 3 billion more birds lived in North America in 1970 than do today — meaning that one out of every four birds was lost in the last 50 years.

These population declines are observed among common species like the white-throated sparrow, as well as rare and exotic varieties. Scientists attribute this trend to a number of human-caused factors including habitat loss, pesticide use, insect population declines, climate change, outdoor cats, and glass skyscrapers.

But organizations like Audubon are working to protect birds, and the data collected during the Christmas Bird Count is useful in helping scientists, policy makers, and citizens develop conservation strategies to protect birds and their habitat.

So this December, Copper Country volunteers will brave frigid winter weather not just for the sport of bird watching, but also to help protect the many bird species that share the UP.

The Houghton Christmas Bird Count will take place on Saturday, Dec. 11, and the Eagle Harbor count will occur later in the month. Individuals who are interested in learning more can find information at Audubon.org.