Love birds Doug Chickering and Lois Cooper do, in fact, love birds.

The Groveland couple spend countless hours together every week birding in area fields.

"Lois and I go on Friday afternoons, every Saturday and Sunday, every holiday and vacation," said Chickering, 66. "It's nice to have something to share with the person you love. A lot of couples meet in the field and get married. And the opposite: if one partner in the couple is a birder but the other isn't, the marriage tends to fall apart."

Chickering and Cooper are not alone. Birding is huge in the region with people of all ages and backgrounds, but particularly among the married set. In fact, 72 percent of the 46 million birders in the United States - including the 2.1 million who live in Massachusetts and New Hampshire - are married, according to a 2001 U.S. Fish and Wildlife study.

Many of the couples are drawn to big birding events, like the Merrimack River Eagle Festival, which attracted roughly 1,500 bird addicts last year. The third annual day-long event this weekend will feature a slew of birding-related activities in the Newburyport area, including guided sightings of bald eagles, demonstrations by wildlife rehabilitators, and kids' crafts and games.

"Birding taught me how to see and what to hear and how complicated and beautiful the world is around me," said Chickering, a machinist by trade. "Lois says birding's like a treasure hunt. You go out in the morning and look for one thing, but you really don't know what you'll find. It just opens the world up. For me and people I know, birding isn't a hobby, it's an obsession."

For non-birders, however, the hobby's allure remains elusive. Why would anyone want to lurk around salt marshes and wetlands in freezing cold temperatures with their eyes glued to the skies? All that head scratching once produced an unfavorable image of birders, recalls 58-year-old birder Steve Grinley, who was hooked after his first birding trip roughly 46 years ago at Cambridge's Mount Auburn Cemetery.

"Back then, I was a closet birder," said Grinley, who now owns Bird Watcher's Supply and Gift in Newburyport. "I didn't want too many people to know I was into birding. I had a few friends I'd go out with. Eventually, I hooked up with a group of birders.

"It was not cool back then - not cool at all. I remember being on birding trips and people passing by would beep their horns and make bird sounds."

These days, local birders are proud of their endeavors. They travel to birding hot spots around the world. They keep "life lists" of the hundreds of birds they've seen, often broken down by year and region. In the densely populated bird region of Newburyport, "you're almost considered coo-coo if you're not a birder," Grinley said.

"People think we're funny looking and middle-aged, and therefore should be laughed at," said Sandy Molloy, 57, of Londonderry, N.H. "But the birders I know, they don't care what people think."

The attraction of the hobby differs from birder to birder, based on their interests and goals. Some want to rack up enormous life lists, while others don't even record what they've seen. Jim Berry of Ipswich is fascinated by the nesting behavior of birds, while Newburyport's Sue McGrath is intrigued by the special adaptations of individual species.

"There are 'chasers,' 'listers,' those into breeding biology, those interested in migration, 'bird banders.' There are 'backyard bird watchers,' 'armchair bird watchers.' There are people who have trips planned for six, seven months to see certain types of species," said McGrath, who runs Newburyport Birders. "At some point, you might have been one or many of those types of birders."

Some, like Jim Fenton of Haverhill, prefer to steer clear of the birding herds and appreciate nature in solitude. But many birders, like Jonathan Brooks of Newburyport, enjoy the social aspects of birding and being part of an accepting community of people bonded by a common love.

"You could travel across the country with a birder and not know if he's married or even working by the end of the trip. You simply talk about birds," Chickering said. "I know three people who go birding all the time: One's a school teacher, one's a house painter and one's a bank president. They have nothing in common, but they became fast birding friends."