It's two o'clock in the morning and the 742 inhabitants of the birdhouse are asleep, their heads tucked under their wings. But in the basement kitchen Red Kilby, birdhouse master chef, is already making peanut- butter sandwiches, pressing bird-food mix into slices of banana and counting out raisins, following 172 recipes tacked up above his chopping block. As deftly as a Japanese chef, Kilby, whose red hair is mainly a memory, arranges the chopped morsels in metal trays. At seven, when the keepers arrive, they will take the proper trays to the proper cages and the birds' day will begin. "As soon as they wake up, they start to look for food. It's important for them to have food right away since they metabolize food faster than we do," explains Sonny Stroman, a veteran birdhouse keeper who will lead a behind-the-scenes tour of the birdhouse this Sunday. The free program, designed to show human visitors a day in the life of the birds and their keepers, is one of a series of Sunday Afternoons at the Zoo, scheduled to run through March 14. One highlight of the tour will be the birdhouse's new cork tree, which not even the birds can tell is made of fiberglass. The tall, many- branched tree, draped with real Spanish moss, is already home to several nesting pairs, and the keepers can climb up inside to check the nests. "I just put that piece of cork up there, and the sun bitterns are already building in it," says Stroman. "There are a lot of holes in the tree for nest boxes, and if we see birds going in and out of them a lot, we check for eggs. Then we candle the eggs to see if they're fertile. A pair of storks built that nest over there -- they used sticks, rags, anything they could find. The male collected them and the female arranged them. When the cork tree was being built, there was a superstructure around it, and to keep the birds from flying into it at night we draped it with toilet paper. Next morning, the toilet paper was in the storks' nest." Some of the birds hatch their own eggs and some eggs are sent to the zoo's Conservation and Research Center in Front Royal. Other eggs are hatched in the birdhouse incubating room, which visitors will also see on Sunday. "This year we hatched 873 eggs here," says Stroman, consulting the official egg book. "We keep a record of every egg in this book. Each egg is given a number and after it we put the species, cage number, date laid, date pulled -- and the disposition. This isn't the season yet. Last year we found the first egg in January." The now-empty incubators, which, in a few months, will hold up to 40 eggs each, turn the eggs automatically, simulating the action of the female birds. "The mother bird turns her eggs three or four times a day with her bill," explains Stroman. "Otherwise the development would all take place on one side. . . The last 24 hours, when they're pipping, is kind of hairy. You kind of worry about them." Visitors will also tour the basement holding area, where birds are kept before being shipped to another zoo or when some problem has arisen in their normal quarters. "This is a female touraco," explains Stroman. "Her mate was chasing her around, so she's here while we redecorate the cage." The redecoration, Stroman adds, is not for esthetic purposes but because touracos are territorial, and the bird that was in the cage first is pretty possessive about it. By giving the cage a new look, keepers try to neutralize the territorial imperative. The toucanets, Stroman says, continuing the tour upstairs in the public area, are having similar problems. "These two want to nest, yesterday," says Stroman. "When birds are rearing young, they need protein. Even seed- eaters give live food to their young. See the male? He's hunting for crickets now, and there should be plenty." In addition to serving meals, checking nests, candling and turning eggs, redecorating cages, mediating between squabbling pairs and providing crickets, the keepers, Stroman says, "do anything that needs to be done." They dig dirty dirt out of the cages and replace it with clean dirt. They hose out the duck ponds and cut the grass, and they also send any birds that don't look well to the zoo vet. "If they're losing weight or are inactive or if they're fluffed up -- if they don't look smooth -- we catch them and look at them. When birds are sick they get cold and put their feathers out from their bodies," the keeper explains. The keepers also have to make sure the birdhouse residents -- with the exception of the migrating ducks, which just board there temporarily -- stick around. "Once an emu got out of his cage," recalls Stroman. "Emus can't fly, but they run pretty fast and we had to chase him. He did an evasive action, but when he got about fifty feet away, he turned around, looked at us, and let us catch him. He was almost as anxious to get back in as we were to get him back in."