It’s early spring 2010, and Rick Petersen is slogging through the mud at Merchants Millpond State Park, the remnants of a pink dawn reflected in the black waters of the pond. Historically, the millpond has been a stopover point for migrating birds as they move north to their summer feeding grounds. However, in a changing climate, the numbers of some types of birds and the dates that they show up is also changing. What kinds of birds would he see this year?

Here in the northeast corner of North Carolina, Petersen is moving through an enchanted forest of huge cypress and tupelo trees decked with Spanish moss and resurrection fern; a mosaic of duckweed and water fern cover the pond’s surface. The pond itself covers 750 acres, surrounded by 3,000 acres of mixed pine and hardwood forest interspersed with shimmering stands of American beech.

Merchants Millpond State Park, near the border of North Carolina and Virginia. Photo courtesy of bobistraveling.

Petersen likes to get out to Merchants Millpond in the spring, before the humidity, ticks, and deer flies get too bad. There aren’t too many people around at this time of year either. And though he doesn’t usually see many animals on the ground, there are plenty here—deer, beaver, bobcats, grey fox, black bear, and snakes.

Some 200 species of birds have been sighted in the park. All through spring, birders show up at the pond with high expectations for spotting colorful migrants—northern parulas, swamp warblers, and yellow-throated warblers—making their way back from the southern tropics to northern breeding grounds. They might also see turkeys, egrets, owls, pileated woodpeckers, and hooded mergansers.

Spring sightings at Merchants Millpond State Park include the northern parula, upper left, yellow-throated warbler, upper right, and hooded merganser, bottom. Photos courtesy of Daniel Berganza, Domenic Sherony, and Glen Smart.

Petersen is particularly excited about his sightings of the red-cockaded woodpecker, an endangered species that prefers to nest in older longleaf pine trees and is rarely sighted at the millpond. “I’m not a professional birder,” he says. “So when I see something like the red-cockaded woodpecker, it’s a real discovery for me.”

Though he claims not to be a professional, Petersen started birding when he was 10 years old, and now counts some 150 birds on his life list. He grew up in New Hampshire and worked 30 years for the Coast Guard, living all over the United States. Elizabeth City, where Petersen has lived the past 10 years, lies about an hour from the North Carolina coast and right in the Atlantic Flyway, one of four major routes that migratory birds take in spring as they leave their winter feeding grounds to fly north to their summer breeding grounds.

Bird migration flyways of North America. Image courtesy of Hunter Allen.

Over the years, Petersen and his wife Karen have noticed changes in the patterns of the birds flying through. “There used to be more snow geese, for instance,” he says. “One of the biggest changes is that you don’t see certain birds anymore. My wife and I talk about the trends, like ‘Didn’t we used to have more chickadees and thrashers at the feeder?’ If you don’t pay attention to the types of birds that are visible every day, you might not notice the difference.”

Rick Petersen goes where the birds are, sometimes by kayak. Photo courtesy of Karen Petersen.

Recognizing short-term trends in numbers of birds takes continuous attention. In order to know how bird populations and migration patterns change over longer time scales—seasons, years, or decades—observers need to record their sightings over time, and compare them with observations from other locations. Though Peterson’s main motivation for birdwatching is to satisfy his own personal interest and sense of adventure, he’s also found a way to contribute his time to a vital new effort to build a long-term record of the nation’s bird distribution…