On Saturday, upwards of 75 binocular-clutching souls will fan out within a 15-mile circle of the Farmer's Market on Lake Wheeler Road and spend the day counting birds.

Gadwalls, wigeons.

Buffleheads, scaups.

Common loons.

"We hope to tally 100 species of birds," e-mails John Connors, who coordinates the Raleigh edition of the annual Christmas Bird Count, a North American inventory of things winged conducted the last three weeks of the year.

Five counts are conducted in the Triangle area (see box), 39 statewide. Nationwide, Audubon, which coordinates the count, expects 50,000 birders to participate at 1,800 locations.

For the uninitiated, Connors describes the count as "the largest scientific social event in the country."

Basically, it's a mammoth, volunteer-led effort to keep tabs on the avian population and detect emerging trends. Among other things, the count is noted for detecting early declines in wild turkey populations in the 1930s and '40s (which prompted wildlife conservation efforts that restored the bird's numbers) and picking up on the declining bald eagle population in the 1960s (which led to a ban on the pesticide DDT, which was found to be weakening the birds' eggshells).

This year, Audubon reports particular interest will be paid to the Gulf Coast region and the effects of this past season's hurricanes on local bird populations.

The count got its start on Christmas Day in 1900, when ornithologist Frank Chapman decided to put a twist on a then-popular Christmas tradition known as the "side hunt." Instead of going out and hunting birds, Chapman and 26 fellow birders decided to count them, 90 species in all on that first count.

Here's how the count works:

Each count stakes out an area 15 miles in diameter. In the case of the Raleigh count, Connors says 15 site leaders take a handful of spotters to a given area and spend the day counting birds.

The counts typically last from sunup to sundown, though Connors has been known to head out before dawn to score some particularly pesky birds. For the Dec. 26 Chapel Hill count, organizer Will Cook says bird counters are typically in the field for six hours.

Because of the number of experienced birders on the Raleigh count, it's a good opportunity for the novice to gain some valuable pointers. Perhaps the most valuable (based on spending the day with Connors' group three years ago): the ability to identify species by ear.

Other counts request that participants have some birding experience.

"It is not a venue for nonbirders or novices," e-mails Carol Williamson, who is coordinating the count on Jan. 1 at Jordan Lake. "I get calls every time from people who like nature but do not even own binoculars."

On some counts, participants gather at lunch to compare notes, then fan out again for the afternoon. At day's end, there's often a potluck.

If you're interested in counting along, check the accompanying "And counting" box.

Backpack the Triangle?

Hankering to go backpacking, but short on time? Or don't know what you're doing? The Triangle offers several locations where novice and experienced backpackers alike can find something to their liking. The Backyard Explorer straps on the pack in Sunday's Travel section.