When someone gives a pet to the children of the United States, who do you suppose ends up feeding it every day and cleaning its cage?

Right now, for instance, there is a new elephant in town, a tardy Bicentennial gift from the children of Sri Lanka (formerly Ceylon) to the children of the United States. The children are enjoying the baby elephant, whose name is Shanti, and the National Zoological Park is feeding and cleaning up after it.

"This is the pleasure and the privilege of being a national zoo," says the director, Theodore Reed. It means that the zoo sometimes gets valuable and/or rare animals free; it also means that it takes anything a foreign country, domestic President or other official wants to give it.

Shanti is a welcome present - the National Zoo needed one, and elephants are up to something like a dollar a pound now. But the history of the National Zoo includes the gracious acceptance of a lot of pigeons and oposums which VIPs wanted to unload. On Jan. 5, 1918, President Woodrow Wilson presented to the National Zoo one "domestic turkey, colored red, white and blue," which someone had just unloaded on him.

Shanti, whose name means "peace," will be presented formally on inauguration day. Just as she had been about to depart for America last year as a Bicentennial gift, the Indian elephant made the endangered-species list, and additional paperwork, including proof that she had not been captured in the wild, held her up. If an elephant is a singularly inappropriate inaugural gift for a Democratic President, the ambarrassment is shared by the givers. The elephant is also the symbol of the political party now out of power in Sri Lanka.

About a year old, Shanti weighs close to 500 pounds. She was an orphan, apparently abandoned by her parents.

Do state gifts get VIP treatment at the zoo? "We have democracy here," said Reed. "Everyone gets the same high standard of treatment." But it might be noted that Shanti is fed her milk out of champagne bottles. (The explanation is that there were a lot of them around after New Year's Eve; besides, as we all remember from then, they are great bottles.)

In addition to getting the gifts that nobody wants, the National Zoological Park gets the gifts that everybody wants. There was a spectacular scramble over the pandas, when the people of China offered them to the people of the United States, and the easiest way of resolving it, Reed knew, would be going with "tradition" and giving them to the National Zoo. In spite of the $500,000 that came out of the Zoo budget to house those pandas, they were ample repayment for the acceptance of all those opossums and turkeys.

Another famous present, although not a state one, was Mohani, the white tiger. The route then was: The hunter who found her asked Reed if he were interested; a donor, Metromedia, was approached successfully; Metromedia presented her to President Eisenhower, and the President passed her on to the Zoo.

Reed has also made a success of "acting receptive" about receiving interesting animals. When then-Attorney General and Mrs. Robert Kennedy were in Indonesia and promised a pair of American swans to then-President Sukarno, Reed could have just sent them off, but decided instead to accompany them and use the opportunity pointedly to admire the country's Komodo dragons. As he had hoped, Sukarno made the present of a pair - but with more style than Reed had anticipated. The Indonesian president snapped his fingers, Reed reported, and "an Air Force colonel with a 45 strapped on his back" stepped out from behind a curtain and took the order. "I kept wondering who the hell else was behind that curtain."

Six year later, after the Zoo had had trouble with one of the Komodo dragons - "You never give an 125-pound lizard an enemz?" - President Soharto was persuaded to produce another one "as symbol of friendship from the people of Indonesia to the people of the United States."

Other state gifts have included: two okapis, a pair among many given out as gifts to different countries by the Belgians, just before quitting colonial rule of the Belgian Congo; nine red kangaroos, which Australia had exhibited at the World's Fair in Montreal and decided not to transport all the way home; ditto on some Japanese goldfish from the Imperial Collection, which had been at Expo '64, an Indian rhinoceros with baby, "because the ambassador heard we needed one"; other elephants, including a previous Shanti, and a lesser panda, also from India; and a tiger named Foa (for Foreign Operations Administration) from Pakistan.

When the Sudan presented some cranes, Reed insisted that they be called "migratory cranes," because the actual name is "common European crane" and he thought that sounded undiplomatic.

As for proper names, he insists that they be designated by the donor-country. Let them make the diplomatic booboos, if any. "When we got the pandas there were all kinds of suggestion - 'Ping' and 'Pong,' 'Pat' and 'Dick.' I decided that if they didn't have Chinese names when I got there, they were sure going to have them by the time I left."

China is well aware that "the whole world goes bonkers over pandas," and the only way foreign zoos get them is as state gifts. We have also gotten tuataras and kiwis from New Zeland and parma wallabies from Australia that way.

When it comes to giving gifts, we have a harder time. The American buffalo is a terrific gift, but China already had one, and Reed was hard pressed when asked to think of a present for the Chinese. The grizzly bear was rejected on the grounds that it was a Russian symbol, and the "rip-snorting puma" because the symbolism of "a carnivorous, ferocious, clawing predator" was considered inappropriate. (Final decision: a pair of muskoxen.)

But we never know what we're going to get, either. Reed was visiting the Paris Zoo one day, when his opposite number asked him whether he would want to see "your elephant" first, or have a drink. Reed, who hadn't known anything about "his elephant," decided on the drink. He needed it, he said, to face the fact that a male elephant, noteriously hard to exhibit in a zoo because of its macho violence, had been presented to President Eisenhower. "I knew right then we were going to have trouble," he said, "but I didn't think we could keep it as long we did." That elephant, named Drimbo, was moved to Lion Country in Florida last year, when Reed decided it had become too dangerous here. It died there last October.

But consider what things were like before there was a National Zoo to send and receive such gifts. Zoo officials are fond of the story, from State Department archives, about the American ambassador who in 1827 received two Arabian horses and one Atlas lion as present from the sultan of Morocco.

It seems that the sultan's guards showed up one day with the presents, and refused to take them back on the grounds that the sultan would have them beheaded if they returned with the unaccepted offerings. "You either take them, or we'll turn them loose in the street," they told the ambassador.

He took them. He cordoned off part of the embassy courtyard for the lion, stabled the horses and began writing the State Department for instructions. The department suggested giving them back. The ambassador, like so many who believe that the department doesn't really understand either their problems or local conditions, continued to write for other instructions, only find that the department took no interest whatsoever in the lion, and only asked about the horses because of their possible re-sale value.

Meanwhile, the animals were eating him out of house and embassy. The total embassy budget for the year was $2,400, and lion ate $7 worth of food every day. The horses, of course, were eating like horses.

Eventually, the ambassador got into serious debt, and then the State Department took action - relieving him of his duties. But although a successor ambassador arrived in Morocco, the original one had to remain there because he was under house arrest until he could pay his debts.

The new ambassador wrote back, too, complaining that his predecessor seemed to be somewhat tetched, as evidenced, among other things, by the fact that "yesterday he attempted to push me out of a window." Eventually, he killed himself.

There are two points to be made out of this story.

One is for those who are interested in diplomacy as it affects Foreign Service Officers and other animals. The three presents were finally taken to America by the Merchant Marine and the horses were sold; there is no record of what became of the lion. But when the sultan gave an American ambassador two lions in 1838, the matter was resolved in a matter of months - because now they had precedent.

The other point is not mentioned by zoo officials who relate this whole business what great glee, but is implicit in it. Who would do the dirty work for the pets of the people and the children of the United States if we didn't have the National Zoo?