Bernard Heath, a retired contractor from Falls Church, looked out his back window this week and saw something strange in the snow.

"Robins. The trees were just loaded with them. And the grass. They were building nests in the azalea bushes and shrubs. Just loads of them."

Wells Burgess, a Justice Department lawyer, saw a flock of 300 fly past his downtown office earlier this week. At first glance, he thought they must be starlings.

Then he saw a rust-colored breast flash through the trees. Like Heath, he wanted to know what was going on.

At the Audubon Naturalist Book Shop in Georgetown, robin inquiries have been as plentiful as the birds.

"Our phones have just been ringing off the hook," said Linda Hardman, manager of the store. "It has been crazy."

Dolores Manns, who works at The National Wildlife Federation, also has noted a sharp increase in calls about robins. "One woman told me she had 4,000 in her yard. They were on the bushes, in the trees, on everything. She said they were just all over."

The Audubon Naturalist Society has two tape-recorded messages this week that say, in part: "Large number of robins . . . . No need to be concerned . . . . Obviously are finding plenty to eat within the Beltway."

Reports of robin sightings began pouring in about a week ago, but there have been higher-than-usual numbers of robins here all winter, the experts say.

Craig Tufts, a naturalist at the National Wildlife Federation, sighted several hundred robins, instead of the usual 20 or 30, during his annual Christmas bird count in the Sterling area.

He suspects those birds have been joined in the past two or three weeks by others, migrating up from the South, following the unusually mild weather here, where February temperatures are averaging four degrees above normal.

They're eating worms, and they're eating berries. "Basically, anything with fruit on it, that they can get into their mouths," he said.

The robins are in no danger of starving, but Tufts says homeowners who want to feed them should scatter dried fruits on the ground -- currants, raisins or chopped apples.

"It's hard for me to say whether there's two weeks worth of food out there, or two months," he said. "But people generally should not be concerned."

Philip DuMont, an active local birder, suggested that some of the robins are year-round Washington area residents, but the bulk are probably winter carpetbaggers from New England that would ordinarily spend February in the Carolinas or Georgia.

Many of the robin watchers around Washington have commented on the size of these birds. "Big suckers," one woman called them.

"The reason they look so healthy is that their gullets are just crammed with berries," DuMont said. "They really do look full."