BIRDLAB - Open Fridays, Saturdays and Sundays from noon to 3, in the birdhouse of the National Zoo.

What do lorikeets eat for breakfast? What bird weighs only as much as three sticks of gum?

These and other questions are answered at Birdlab, a learning center in the National Zoo's birdhouse. But a question more frequently asked there is:

"Who killed those birds?"

"Nobody killed them," the volunteer on duty will explain patiently. "They probably just died of natural causes, and somebody found them and stuffed them."

Kids may still be suspicious, but after they stroke the stuffed woodpecker, gingerly, and look at the owl's skull with a magnifying glass that lights up, they lay suspicion aside and start to check out learning boxes.

"Just sign your first name so we can keep track of how many times each box is checked out," says the volunteer to a little girl who can barely sign her first name and needs help carrying the box of birds' nests to a table. Nests are shaped like bowls, saucers or sacks, according to explanations on cards in the box. The child is asked to match the description of the eastern phoebe's nest with the real thing.

"Look, they killed that bird to get its feather," says a kid who pops in, looks at a bird-of-paradise plume, and pops out before the volunteer has a chance to clear herself.

For kids who stay longer, there's a box of feathers to check out. Most feathers, explains a card that comes with the feather sampler, are working feathers. They work to facilitate flight and to camouflage. Even the pretty pink and red feathers in the box are described as working feathers because they work to attract mates.

"What are mates?" a kid asks his mother, who hastily checks out the egg box. The eggs are all blown and filled with wax and the biggest belongs to the ostrich.

"It looks like a grapefruit that's lost all its color," says a girl who examines it with a magnifying glass and invites her mother to feel the texture of the shell.

"It has to be tough," says her mother. "I guess the mama treats it right rough."

"Can he just touch a baby chick?" asks a father of a boy attracted by a glass case of chicks visible through the window. The volunteer takes a chick out and the fuzzy bird is patted gently by the child, who exits without glancing at the dead specimens.

A gutsier child is looking through a box on bird diets. There are cans of carrot juice and small samples of shrimp meal and other bird favorites, along with recipes. For flamingos, it seems, you add a dash of groundup oyster shells.

"I don't even like the smell of this box," says the child, who turns out not to be so gusty after all.

For a less visceral experience, the kid checks out a box on bird songs and is told by a cassette that birds sing mainly for two reasons -- to attract mates and to claim territory.

"Because birds sing faster then we can interpret their sounds, we have had to slow down their dongs to study them," says a recorded human voice that has been slowed down to illustrate the point.

To illustrate wingspans, there's a box with a measuring tape and some long pieces of silky material. The tape ends at five feet, and a kid finds that the bald eagle's wingspan is even longer than that. Another child and her mother unfold a piece of material representing the longest wingspan of anyknown bird -- that of an albatross.

"Keep walking," says the mother to the child, who is holding one end of the wingspan. When the material runs out, mother and child are at opposite ends of the room. w

"Is that bird in the Zoo?" asks the child. "I don't think it would fit."

A tiny piece of cloth represents the wingspan of the red bishop of Africa, which doesn't need a lot of wingspan since it only weighs as much as three sticks of Wrigley's gum, the wrappers of which are attached to the cloth.

The box on nest sites shows where birds lay their eggs and why they choose a site. Woodpeckers lay their eggs inside trees and the eggs are white since they don't need protective coloration. Eggs laid on beaches or in creek beds, however, are speckled like pebbles.

"These eggs are laid in trees," reads a mother to a very little boy.

"Look, that's another egg," responds the kid, who may not be ready to learn the whys and wherefores of nest sites.

Another family group laughs over books of feet, crests and bills. The picture of the animal is covered with an oversheet with a hole cut to reveal only the body part in question.

Kids who really get interested in bills can check out clipboards and take a pamphlet called "Draw a Bill." There are seven birds on the pamphlet, all of which look weird because their bills are missing.Clipboards under their arms, the kids wander around the birdhouse to look for live models -- the Moluccan cockatoo and the northern oriole, until recently the Baltimore oriole.

The size and shape of bird's beak are often related to what the bird eats, the pamphlet says, but the toucan's bill is a puzzle. It's big and rainbow-striped, observes a kid craning her neck to study two toucans at the top of a tree in a glass cage. Scientists have concluded that the toucan's bill may be the way it is so toucans can recognize each other, which may well be underestimating toucans.

The Moluccan cockatoo's beak is more utilitarian and thus more satisfying to scientists. The cockatoo uses it to crack open seeds and nuts and to cling to branches. But while two little girls stand in front of the cockatoo cage trying to sketch, the birds appear to be using their beaks to manicure their claws.

"Can I draw the mouth open?" says a kid who can't wait around for the cockatoo to close it.

A group of ducks on a small indoor pool attracts some sketchers. (The duck's bill gathers algae from water.) The kids sit on the retaining wall at pool's edge trying to get just the right curve to the bill, until some of the duck's more exotic roommates waddle near to look over the artists' shoulders. The kids retreat hastily to Birdlab to return the clipboards.

A new roomful of people has arrived to check out boxes and accuse the volunteer.

"Did you shoot them?" asks a kid, gesturing at the stuffed birds.

"No," says the volunteer who has become almost defensive. "The people here love animals. We wouldn't hurt them. They probably just died of natural causes and . . ."