For 65 years, bird enthusiasts have been reporting to the Westport area in December to participate in an annual Christmas bird count. The concept of counting birds dates back even further -- 112 years to be exact -- when the National Audubon Society launched the effort.

Sunday was the occasion for this year's count, as volunteer bird watchers at all levels of experience spent all or part of the day in the field at various locations within a 15-mile wide "count circle." The circle was centered at Westport's Twin Bridges on Route 57, and included "hot" bird watching locales in Westport, Norwalk and Fairfield. Others conducted backyard feeder counts.

The object was to identify and count each species of bird seen and record how many of each type are seen in a day. All the data from the Westport count, as well as 16 other counts in Connecticut, is provided to the National Audubon Society.

Connecticut is not the only state that counts the bird population. More than 1,700 other bird counts are conducted simultaneously nationwide and throughout the Americas, and the results are published in a document titled "American Birds." The Audubon count is the longest-running annual census of bird populations in the country, thanks to some 44,000 volunteer birdwatchers.

Frank Mantlik, a Stratford resident who works as a mailman in the Compo Beach area, has been participating in the Christmas bird count since 1977, close to 40 years. He served as the Westport count compiler and captain from 1979 to around 1994. The area captain is now Mardi Dickinson.

Since the participants are all volunteers, the names and faces of counters continually change over the years, said Mantlik. The number of participants has also declined over time due to people getting busy at Christmastime, he said.

Property development has been an issue for local bird populations, Mantlik explained. "Where there were nice thickets, there are now manicured lawns. Still, there are local parks and beaches for birds to explore," he said.

And there's usually an amazing sighting.

"This morning, I found a yellow-breasted chat, considered a warbler species," Mantlik said Sunday. "It's unusual any time of year. I saw this one at Taylor Farm Park in Norwalk. I also saw a double-crested cormorant, which is unusual in the winter months. They are more common in summer, when they breed on our offshore islands."

The day started early for Mantlik, at 7 a.m. He and others gathered at Veterans Park in East Norwalk, before covering Calf Pasture Beach, Taylor Farm Park, Canfield Island, the banks of Norwalk River and Westport's Saugatuck River shores. Because the day was windy and temperatures were only in the 20s, Mantlik donned five layers of clothing, including two sweaters. As for equipment, he carried binoculars, a spotting scope for long-distance viewing, and a digital camera in case of a rare sighting.

"I look forward to this," he said, "and put off holiday errands to do it. It often becomes a competition to see who found the rarest bird. You try to get accurate totals, and have to be quick."