James Buchanan, 77, a Miami Herald reporter who was jailed by Fidel Castro in the Cuban leader's first year in power, died Saturday in Miami of a stroke. He was 77. In 1959, Mr. Buchanan was arrested after he interviewed and gave supplies to an American mercenary who was being sought by Mr. Castro's revolutionary government. He was tried and sentenced to 14 years in prison but was freed 12 days later on the condition that he never return to Cuba. He was part of the Herald team that covered the failed Bay of Pigs invasion in 1961.