Luther and Mary Martin are the perfect hosts.

Luther, a retired federal engineer, prepares breakfast around 6 a.m. and sets it near carefully arranged heat lamps. Mary, a retired nurse, warms snacks in her microwave throughout the day.

For special treats, the Vienna couple will run their empty clothes dryer so their guests can luxuriate outside in the toasty air of the exhaust vent; and they keep a bowl of fruit on hand--albeit rotting fruit--because it attracts the tasty fruit flies their visitors love.

The Martins' home has become the winter haven for three hummingbirds, at least two of them rare in these parts. The spectacle of rufous hummingbirds flitting around a Northern Virginia yard in dead of winter has become the buzz of birding circles here and afar, bringing binocular-toting gawkers from as far away as Florida.

In the process, the Martins are as busy as the parents of triplets.

The colorful avian show right outside their kitchen window has drawn flocks of birders, a busload of biology students and even the town police to their quiet street.

Indeed, the tiny hummers have taken over the Martins' lives, but they're not complaining. "We've gotten so much out of it," Mary Martin said this week as yet another visitor dropped by to see the creatures. "The people are so interesting. The birds are just fantastic. Every day it's something new."

In return for the daily doting, the hummingbirds seem to respond to Martin, sometimes following her in the yard and landing on her hair. She has named them "Ms. Rufous," "Spot" and, for lack of something better, "No. 3."

Ms. Rufous and Spot are females, Martin knows, because they've been caught, examined and banded by a bird specialist. Ms. Rufous, who Martin first saw in September, is "the queen," sometimes chasing the two others away.

Luther Martin takes charge of the day's first feeding around sunup. He built special stands for the couple's two bird feeders, adding heat lamps to keep the sugar water inside from freezing. A few weeks ago, he rescued two discarded Christmas trees and placed them nearby, with another heat lamp, to provide a perch and cover.

"I can't believe any of this," said Mary Martin, who before the hummers appeared was more into butterflies than birds. "I can't believe these birds are here. I can't believe these people come for miles and miles and sit outside for hours and hours" watching them.

Martin knew little about hummingbirds when she first noted the unusual species in September, amid the migrating ruby-throated hummingbirds that are most common in the Washington area. When a tiny hummer stayed behind, she worried it would die in the cold. Birders advised her not to be concerned.

As word spread that her visitor could be a rare rufous, one of 20 species of hummingbird in North America, serious birders began turning up at the Martins' doorstep. Some mornings, Mary Martin looks out her bedroom window to see four or five people in her yard with telescopes or binoculars. Recently, a woman stopped by the day after her release from the hospital after a mastectomy.

With as many as two dozen people showing up on any given day, the guest book Martin maintains is filling up fast. "We counted up into the hundreds" of names, said Luther Martin.

Early on, neighbors thought the birders' telescopes were cameras and wondered why the media had descended. One day, a police car pulled up and a wary officer got out to ask what was going on. He ended up looking happily through the birders' scopes for 10 minutes at the three-gram fluttering sight.

Most visitors have been polite, keeping to the sidewalk; Mary Martin sometimes invites them in for coffee. In return, some have brought gifts such as bird magazines, coffee mugs with bird themes, and seed. "I cannot believe how people are so excited," Martin said. "One lady started crying. It just blows our mind."

The rufous hummingbird breeds on the West Coast and winters mainly in Mexico, with small numbers in Texas, the Gulf Coast and Southern California. How the birds got to Virginia is a mystery.

Any bird that migrates has the potential to get lost, said John Sterling, research biologist at the Smithsonian Migratory Bird Center. Some birds get blown off course by wind currents; others may have genetic deformities that disorient them. Sterling said some ecologists theorize that, as habitat is destroyed when forests are cut, birds "wander a little bit more."

Some experts think there may be a resident population of rufous hummingbirds on the East Coast. Notwithstanding their small size and constant need for food, rufous (named for the brown-red patch on the male's back) are hardy birds, these experts say.

Mary Martin has been told her hummers might have made it through winter even without her care. "They are amazingly tough little guys," she agreed. Even so, she said, "they're just so little. I've had it in my hand. You don't even feel it. It feels like a warm feather."