When Raymond Bonner bellied up to the keyboard on Feb. 3, 1986, to begin writing his book on U.S. relations with the Ferdinand Marcos regime, what worried him most was finding a proper way to end it.

Before the month was out, Marcos had fallen, Corazon Aquino had been swept into office on the shoulders of "People Power," and Bonner, much relieved, had a spectacular finale.

More important, as it turns out, he had a huge head start.

"Waltzing With a Dictator," published in May, arrived in bookstores comfortably ahead of the tidal wave of books on the Marcoses, Aquino and the Philippines that threatens to inundate the American market in the coming months -- and to drown all but the hardiest contenders for readers' attention.

These books -- at least 15 are currently on the market or in the works -- illustrate the phenomenon of bunching that afflicts American publishing from time to time. Most frequently a herd of like books emerges in the wake of a major news event, when one editor after another, and one author after another, has the same brilliant idea.

The stampede to develop literary properties about an event like the Watergate scandal -- or, this year, the unfolding Iran-contra affair -- can hardly be faulted, even if many of the books are bound to be financial losers. But even much narrower topics produce multiple book projects.

Within the next year or so, for example, American publishers will issue four books on the city of Miami, four books on the Bingham publishing dynasty of Kentucky, and four books on the Benson murders in Florida -- at least three more on each topic, in other words, than the market is likely to bear.

There's more to say about the Philippine revolution, of course, than about the traumas of the Binghams or the Bensons. Yet as proposals for Philippines books were circulating during 1986, even the dimmest publishing executives must have appreciated the risks of putting any one of them under contract: Competition for review attention, for shelf space in bookstores and for the finite interest of a finite number of readers was certain to be intense.

"The conventional wisdom in publishing, and the real wisdom, is that on headline subjects like the Philippines or Iran-contra or PTL you have to be either the first or the best," comments Washington literary agent Raphael Sagalyn, who does not have a client writing a Philippines book.

Not only was Bonner's book one of the first out of the pack, some of its contents generated the kind of news a publicist dreams about: a public dispute with Richard Nixon, who denied that his administration had given President Marcos tacit approval to enact martial law in 1972, as Bonner reported.

M.S. Wyeth, executive editor of Harper & Row, is happy to settle for the alternative to being first. He will be editing one of the more expensive publishing gambles in this area, Sterling Seagrave's "The Marcos Dynasty," when the manuscript is completed. Seagrave, who wrote the bestselling "The Soong Dynasty," reportedly was paid a $300,000 advance for his Marcos book.

"People will eventually say they've read enough," Wyeth says. "Hopefully that won't happen before the Seagrave book comes out." Originally scheduled for publication this fall, Seagrave's book has been postponed until next year -- for reasons unrelated to prospective competition, Wyeth says, but much to the relief of some of the competitors.

Bonner, whose book was conceived and in progress before most of the others, says, "I just knew none of them could catch me." Even so, his is not the only book in print already.

Bryan Johnson, a Canadian foreign correspondent, was able to complete "The Four Days of Courage: The Untold Story of the People Who Brought Marcos Down" in time for May publication by Free Press/Macmillan. And last month, Braziller brought out "Corazon Aquino: The Story of a Revolution" by journalist Lucy Komisar.

Johnson and Komisar, like many of the authors writing Philippines books, were on the scene for the "snap election" and the revolt that followed. "The Filipinos were saying 'You can't see the sky for the parachutes' because of these parachute journalists flying into the Philippines with no foreknowledge" of the country or its history, recalls writer David Haward Bain.

Unlike many of his colleagues in the press contingent 18 months ago, however, Bain had written a book about the Philippines long before. His "Sitting in Darkness: Americans in the Philippines" (Viking, 1984) has become an honorary member of this year's bunch; a new paperback edition, updated to include his coverage of the Aquino victory, is being issued this year.

But as one of the few lay experts not publishing a new book on the subject, Bain has become a popular fellow with newspaper book review editors: He reviewed Bonner's book for Newsday, Komisar's book for the Los Angeles Times, Johnson's book for The New York Times and a reissue of an Imelda Marcos biography for The Philadelphia Inquirer.

The autumn wave of Philippines books will be keeping Bain, and other reviewers, busy -- though not nearly as busy as the publishing houses struggling to single their titles out from the pack. The fall list alone includes:

"Worth Dying For" (Morrow), by Lewis M. Simons, who shared the Pulitzer Prize with two of his colleagues at the San Jose Mercury News for uncovering Ferdinand and Imelda Marcos' hidden wealth outside the Philippines.

"Inside the Philippine Revolution" (Norton), by William Chapman, a former Washington Post reporter, now a free-lance writer living in Japan.

"Revolution from the Heart" (Oxford University Press), by Niall O'Brien, an Irish missionary priest imprisoned by the Marcos regime.

"Endgame: The Fall of Marcos" (Franklin Watts), by Ninotchka Rosca, a Filipino journalist who also was imprisoned by the Marcos regime.

"Inside the Palace: The Rise and Fall of Ferdinand and Imelda Marcos" (Putnam's), by veteran journalist Beth Day Romulo.

The writers at work on the subject, however, don't seem to be baring their fangs at one another. "It's been like being in a club," observes Katherine Ellison, another member of the Pulitzer-winning San Jose team, whose biography of Imelda Marcos, "Secret Weapon," is scheduled for publication by McGraw-Hill next spring. "Despite all the competition, I haven't seen any real unpleasantness."

Sandra Burton, a Time magazine correspondent who covered the revolution and now is working on a Philippines book for Warner, says, "We do seek each other out. {Raymond Bonner} said he'd become such a bore to all his friends he looked forward to talking to somebody who was passionate about the Philippines." Burton's book, also due out in 1988, is tentatively entitled "Murder at the Airport" -- a reference to the pivotal moment in 1983 when Aquino's husband Benigno was assassinated.

Both Burton and Ellison praise Bonner for his generosity in sharing official documents he obtained through the Freedom of Information Act. The National Security Archive in Washington, where those papers are housed now, has been a crossroads for many of the writers, Ellison notes, as has the coffee shop of the Manila Hotel.

"I wish I was the only person writing about it," Burton admits, but "I would have written about it whether anybody wanted to read it or not. ... It's something that I covered and lived with for four years. I wanted to write it for my own psychological therapy and to tie up loose ends before I went off to another assignment."

One author in the field who seems serenely unconcerned about the bunching of Philippines books is Stanley Karnow. A veteran newspaper and magazine correspondent in Asia and the author of the massively successful "Vietnam: A History," Karnow went to work on his Philippines book before Bonner or any of the others -- and probably will see it appear after all of them.

"I never had any feeling that I wanted to be exclusive about the subject," Karnow says. "If you want to open a gas station, the best place to open it is across from another gas station. The more the public is aware of the subject, the better it is for selling books."

Karnow says his book, tentatively entitled "The Philippines: America's Colonial Legacy," will be published in conjunction with a planned three-part PBS television series he is producing -- probably in late 1988.

Then there are the books about the Philippines that won't be published. Rep. Stephen Solarz (D-N.Y.), chairman of the House foreign affairs subcommittee on Asia and Pacific affairs and an outspoken critic of the Marcos regime, circulated a proposal for what his press secretary, Robert Hathaway, describes as "a recapitulation and summation of the role Congress played" in the transfer of power to Corazon Aquino. According to Hathaway, Solarz eventually abandoned the project because "it would be a lot of work and not make that much of a contribution."

Robert Shaplen's experience was more telling. A reporter esteemed for decades of perceptive reporting on Indochina, Shaplen also has been writing about the Philippines, chiefly for The New Yorker, since 1945. So it was not surprising that his publisher turned to him for a book after the Philippine revolution last year.

"I'm not anxious to just do another book. It's got to be something worthwhile," the 70-year-old journalist says. "They wanted it late last fall. I think they realized they were running into a whirlwind of books.

"They said, 'First or not at all.' And I said, 'Not at all.' "