Naturalist Jean Tierney cradled an Audible Audubon bird-caller, striking up the music of the yellow-shafted flicker woodpecker.

"Yeah, I've heard that," 10-year-old Rory Flannagan said, a smile on his face and a spark in his eyes. "I heard it the other day, down in the park."

Beside a roaring fire in the Watkins Nature Culture Center in Upper Marlboro, Tierney, several kids and a couple of parents listened to the recorded strains of the screech owl, the sparrow hawk, the bluejay, the cardinal, the Carolina wren and a dozen other species that carry tunes hereabouts. Later, armed with their Audible Audubon, they'd venture out of doors in search of singers and their songs.

"This is one of the easiest ways to get into bird-watching," Tierney said of the hour- long sessions, held once a month on Saturday mornings. "In the past, country children more or less learned it from their parents. But these days, children don't get much much of a chance, and the parents don't know, either."

In the nature center -- an airy, light-filled space boasting a barn owl in a cage, a well- stocked fish pond, an Indian longhouse, herb house and other attractions -- they sat by a picture window, through which chickadees, bright-red cardinals and white- throated sparrows could be watched hopping from bush to bush in Watkins Regional Park.

Doug Patton, 15, a volunteer junior naturalist, lounged with his pet possum resting comfortably across his shoulders. The possum looked to be listening, too, as Tierney played the bird calls.

"Here's the bard owl," she said, pushing a record-card graced with a picture of the species into her battery-powered Audubon. "Its song is like 'Who cooks for you? Who cooks for you all?' Can you hear that?"

Rory Flannagan, his friend Brian Baltimore -- both regulars in the nature center's "tenderfoot" program -- plus five other kids all nodded that they could.

"I like all the animals," said Brian, 10, who bicycles from home to do odd jobs at the center once a week. "I like snakes especially, and also feeding the fish. It's just fun around here."

At length -- after the titmouse, northern oriole, bobwhite and bluebird had been heard -- Tierney led her charges outside, through woods and into a nearby field. It was a gray day, threatening snow. The people shivered as a crow started to caw.

Tierney played the cardinal recording. No response. Then the song of the white- throated sparrow. Then the cardinal again. Tierney smiled at the silence. "Let's 'pssssshh' for the birds," she said at last. "It attracts them for some reason. Sometimes you can get them to come right up to you."

Everybody made a "pssssshh-ing" sound. No birds came. Everyone "pssssshhed" some more. Finally, there was a reply. A military jet swept noisily out of the clouds.

"That's an Alpha," said Doug Patton, making the identification.

BIRDS OF A FEATHER The Watkins Nature Culture Center, at 301 Watkins Park Drive, will hold a bird-calling session this Saturday morning at 10. To find out about that, and other free programs, call 249-6202.