They’ll be peering for peepers through telescopes and binoculars.

For more than a century, bird lovers have flocked to their looking glasses to participate in the country’s longest-running wildlife survey, the National Audubon Society’s Christmas Bird Count (CBC).

From December 14 to January 5, armies of avian enthusiasts fan out across the nation in “count circles” to tally their findings.

“For more than a hundred years, the desire to make a difference and experience the beauty of nature has driven dedicated people to leave the comfort of a warm house during the holiday season,” said Missy Siders, a Bureau of Land Management biologist, in Colorado’s Montrose Daily Press.

Many organizations are involved in the count, with many opportunities available for volunteers.

According to the Massachusetts Division of Fisheries and Wildlife, families, students, birders, and scientists armed with binoculars, bird guides, and checklists embark on this seasonal mission—often leaving before dawn.

The data collected by bird observers over the past century allow researchers, conservation biologists, and other interested individuals to study the long-term health and status of bird populations across North America.

When combined with other surveys such as the Breeding Bird Survey, the CBC provides a picture of how the continent’s bird populations have changed in time and space over the past hundred and fourteen years.

In Massachusetts there are 33 geographic “count circles” where bird counts occur. Each count circle is coordinated by an experienced count compiler who works with teams of birders who have signed up for that circle’s bird count.

Beginning birders can join a group that includes at least one or two experienced birdwatchers in charge of covering a portion of the circle.

The Audubon Society says count volunteers follow specific routes through designated 15-mile diameter circle. They count every bird they see or hear all day.

This isn’t’ just a tally of species. All birds are counted all day long, providing an idea of the total number of numbers in that designated zone.

Plus, bird counting isn’t exactly a stationary undertaking. An article in the Herald of Everett, Washington told of cyclists, walkers, boaters, and kayakers taking part.

“It a unique science endeavor that has increasing value for action as a barometer for regional land-use trends by showing where regional bird populations are located,” Pilchuck Audubon Society’s Scott Atkinson told the paper.

Atkinson is count compiler involved in the CBC for some 40 years.

“It’s an all-volunteer effort but the effort does accurately reflect, in most cases, the population trends for birds,” he said. “It’s a low-cost, cost-effective healthy entertainment right in the neighborhood.”

There were more than 2,100 bird counts with nearly 60,000 participants during the annual event in 2008, according to figures from the National Audubon Society.

The count’s origin is traced back to Christmas Day in 1900 as an alternative to an event called the “side hunt” where people chose sides, then went out and shot as many birds as they could, according to the National Audubon Society website.

An ornithologist proposed to count birds instead of shoot them.

On that day, 27 dedicated birders from Toronto to California tallied nearly 90 species of birds.

To find a count circle, go to birds.audubon.org/get-involved-christmas-bird-count.