In an era when American Presidents have been careful to take American vacations on Colorado ski slopes, California golf courses or Georgia trout streams, President Reagan this week relaxed at a Caribbean oceanfront cottage where the ''Bleep-bleep-bleep'' of tiny tree frogs echoes through the evening air.
During the day, the ocean shimmers in the bright sunlight with differing shades of aquamarine and blue. Goats meander occasionally on the nearby roads. Lizards scamper through the trees, bats come out at night, and the neighbors complain that entire families of monkeys come in and rip the orchids to shreds.
Surely few recent presidents have spent a holiday in such exotic surroundings, and Mr. Reagan has more than once betrayed a certain discomfort at being here in the tropics at a time when parts of the United States are still struggling to get out of the grip of winter.
Only a few hours after arriving in Barbados on Thursday, Mr. Reagan heard from Prime Minister J.M.G. Adams that the publicity from his visit had already unleashed a flood of telephone calls to the Barbados Tourist Office in New York.
''I don't think it had anything to do with my visit,'' Mr. Reagan replied. ''It's snowing in New York.''
In brilliant sunshine, Mr. Reagan and his wife, Nancy, attended Easter services at St. James Parish Church this morning before having a final lunch at the home of their hostess this week, Claudette Colbert, the actress.
The 109-year-old brownstone church, shaded by palm and red-blossomed frangipani trees, rang with Anglican hymns while doves fluttered in the eaves as the Reagans joined other worshipers in kneeling in prayer and taking communion. The church was decked with yellow zinnias, white orchids and red ginger lilies.
The only vaguely political note was struck by Duncan Parris, a lay reader, who prayed for peace, ''especially for a peaceful settlement between Britain and Argentina over the situation in the Falkland Islands.''
As he left, Mr. Reagan was asked how he had liked his vacation.''Just fine, yes,'' he replied with a smile. Then he sped off to Miss Colbert's and left early in the afternoon aboard Air Force One for Washington. He was back home this evening.
It is not clear just whose idea this vacation was, since many on the White House staff are known to have opposed it on political grounds. Some suggest that Mrs. Reagan was the one who wanted to accept a longstanding invitation from Miss Colbert, who has been vacationing here for years.
Only after the Barbados trip was announced did the White House arrange for Mr. Reagan to meet with leaders of five Caribbean nations to discuss his proposals for regional economic development. And only a few weeks ago was his overnight stop in Kingston, Jamaica, added to the schedule.
It all seemed to be part of an effort to add work to justify the trip; if so, the White House staff outdid itself. Mr. Reagan was so visibly exhausted after the first two grueling days of meetings in Jamaica and Barbados that he seemed to need desperately the relaxation that had been the reason for coming here in the first place.
While here, the Reagans, along with William F. Buckley Jr. and his wife, Pat, stayed at the Mediterranean-style home of friends of Miss Colbert. They were ferried by helicopter from that house to the Colbert cottage six miles away, where they spent much of their time Friday and Saturday.
On an island where the men, especially the Europeans, wear bikini bathing outfits, Mr. Reagan ventured out from the Colbert garden in boxer swim trunks to skip a few rocks on the shore, plunge into the surf, and swim vigorously using the breastroke and crawl that he first learned when he was a lifeguard in his youth. Photographers captured the moment as Mrs. Reagan waded cautiously into the water, and later White House officials maintained that the Reagans did not resent being photographed on the beach. Resentful or not, Mr. Reagan canceled a planned photo session of himself the next day.
Offshore sat American naval vessels and a communications ship with emergency hospital facilities that presidential aides said did not exist on the island. A couple miles away, the White House staff set up shop at a shorefront hotel, where signs on the beach warned guests against spiny sea urchins and the poisonous apples of the majestic manchineel trees.
For Barbados, Mr. Reagan's visit was an obvious boon. Not that the island had never seen important visitors. George Washington came here in 1751 at the age of 19, and contracted smallpox, although he praised the island for its beauty and hospitality. Many presidents have been here since, but none while serving in office.
Barbados is a pear-shaped, relatively flat coral island about twice the size of Washington, D.C. with beaches of silky white sand that draw tourists from all over the world. A former British possession, it retains a flavor of English civility with English street names, English shops and a Trafalgar Square in the center of Bridgetown.
But most of the island consists of miles and miles of sugar cane fields, a few factories, crumbling roads and tidy but somewhat ramshackle stores and houses serving a population of 250,000 with a per-capita income of a little more than $3,000 a year. Mr. Reagan flew over these parts of the island but never visited them.
Since tourism has replaced sugar cane production as the country's biggest money-maker, local newspapers reported that the Barbadians were delighted to have the Reagans visit.
In their honor, Barbados issued commemorative stamps, repaved several roads, repainted some public buildings and relocated some Canadians from a Hilton Hotel to make way for the American press and staff.
Two local calypso groups also recorded commemorative songs that have been on the radio all week. One verse from ''Ronald and Nancy in Barbados'' by Jimmy Duncan and Malcolm Taylor employed some poetic license about the American invasion to capture the madness: Can't find a house, they take to the
Hilton, Book the entire place. Helicopters down from the airport, Roads don't have enough space. 3,000 people cruising with Ronald, C.I.A. all around. Media reports on the hour, Bulletins from Bridgetown.
The cost of this trip? Some estimates suggest that it exceeded $3 million for everything from the hospital ship to the helicopters, secure comunication lines and special firefighting equipment brought in. But Larry Speakes, the Deputy White House Press Secretary, refuses to give out any figure. ''We'll wait until all the bills are in,'' he said, with the hope that by then the spring sunshine in the United States will have erased the memories that the Reagans were sunbathing while many Americans shoveled snow.