There it was, perched serenely on the 35-17 runway sign of the Katama airfield: a red-footed falcon, Falco vespertinus, the first sighting of its species on this side of the Atlantic Ocean.

The news was heralded on the front page of The New York Times, in the Boston Globe, across the Internet. In birding circles, this was a spectacular event - once in a lifetime, some called it, that a species would be recorded venturing thousands of miles off-course, settling so far from its natural range.

It was spotted Sunday by Vineyard ornithologist Vernon Laux, who sent a digital photograph to Harvard ornithologist Jeremiah Trimble for identification. Soon, birders across the country were waking each other in the middle of the night with the news.

For Dave Klauber, Arie Gilbert and Kevin O'Leary, who started driving to the Vineyard from Long Island, N.Y. at 2:30 a.m., it was a journey of cars, boats and taxis. They caught the 6:30 a.m. New Bedford fast ferry to Oak Bluffs, then a cab to Katama.

Mr. O'Leary said, "You had a goal, and you achieved it. I once drove 1,200 miles to see a hummingbird, and if this bird was 800 miles away, I'd do it."

Mr. Gilbert, a chiropractor from North Babylon, N.Y., looked up momentarily from his telescope to explain that sighting the falcon was "not a tangible achievement, but it is like any other milestone that you pass."

A small, festive group collected at the restored sand plain outside Whosie's diner on Herring Creek Road. There were clots of people with telescopes and binoculars, hushed conversations about feather shafts and colors. Any movement was excitedly narrated.

It was a collective experience.

Nora and Tony Nevin, "amateur enthusiasts," wandered among the cordial group, many of whom offered to share their magnified views as the falcon posed. "Ooohs" and "ahhhs" accompanied his flight pattern as he swooped over the airfield, oblivious to planes and even the occasional helicopter. Walking among the birders, one could overhear the retelling of the same who, what, when facts.

The falcon, a medium-size, grayish bird whose striking feature is its brightly colored red legs, probably came from Africa and arrived by one of several possible routes. Able to travel thousands of miles, it relies on instinct to guide it. For this bird, a first-year male, the question as to why has remained a mystery.

Virgil Taylor, a fifth-grader from California whose family is renting a home in Katama, found the article in the Times and rode his bike over to bear witness. He was in good company.

Serendipitously, under a white tent next to the Katama airfield, The Nature Conservancy was at the same time and place, holding its annual donor appreciation breakfast for about 30 of its members.

The sand plain is managed by The Nature Conservancy, which uses a regime of mowing and prescribed burning to replenish the land. It is to its credit that the grasshopper sparrow is once again breeding there.

That their annual event coincided with the falcon's arrival charged the atmosphere with celebration. Eastern Massachusetts program director Tom Chase, a smile fixed to his face, was ebullient. Tess Bramhall, Rose Styron, Jeanne and Malcolm Campbell looked out on the field with reverent fascination.

The presence of the falcon gave dramatic affirmation of the Conservancy's raison d'etre: "To preserve plants, animals, and natural communities by protecting the lands and waters they need to survive."

Like a gospel chorus, Conservancy members in their green polo shirts and hats, sang the praises of having provided a place the falcon found suitable. That he got here was an accident, they said, but that he chose this place, rich in those things that provide habitat, dragonflies, grasshoppers and small rodents, was a result of their efforts.

"Proof of the pudding," said Phil Henderson, land protection coordinator for the Conservancy's Islands program. "You put in years of effort in restoring and learning to manage a place like this, and this is the reward."

Island writer and naturalist Matt Pelikan agreed, "This is what birders like to have happen."

As to this vagrant raptor's future, Mr. Pelikan, after noting that we are simply observers, stated, "It's totally free. Nobody knows what's going to happen. It could be here for days, maybe weeks, judging from how similar vagrants have behaved in the past."

A longtime bird watcher, he said he's learned to expect the unexpected. "This has sent this birder back to his European field guide to look for birds with similar patterns. It makes you wonder how many you've missed."

And so it was reported birders are on their way from California, Ohio, Florida. Scores of people who have come to observe will be met by scores more.

"Not everyone would want to do it," Mr. Klauber shrugged. "But it's like all the thrill of hunting, the chase - without hurting the animal." He paused to consider how to explain it, then offered, "Why do people golf in the rain?"

For current information on the falcon, visit www.massbird.org and follow the "Bird sightings" link. Locally, the Island birding hotline supported by Felix Neck Wildlife Sanctuary, at 508-696-7577, will post a notice on its answering message if the falcon leaves the Katama airfield area.