I don't know about 'headhunters' but whaling ships often recruited (and sometimes kidnapped) Pacific Islanders as crewmen and there are accounts of some Hawaiian (Kanaka) seamen returning to New Bedford and settling there.

From: Hawaiian Music in Motion: Mariners, Missionaries, and Minstrels by James Revell Carr:

By the mid-1830s New Bedford, Massachusetts, of "Nu Bedefoda" as the Hawaiians called it, had become the whaling capital of the United States and Hawaiians were settling there as well. The first Kanaka whalers to arrive in New Bedford were two young men from Lahaina, Maui, called Joe Bal and Jack Ana. When they arrived in June 1821 aboard the ship Balaena, they aroused the same sort of public interest that Amasa Delano's "boy" Bill had caused in Boston, .... Even though they returned to Maui on the next voyage of the Balaena, other subsequent Hawaiian visitors to New Bedford stayed and settled there. An obituary in the New Bedford Weekly Mercury of January 15, 1836, reports the death of a native Hawaiian whaler named Peter Perry, who had, by age of twenty-six, become a successful boatsteerer on a prominent Massachusetts whaling ship, the Pacific, married a woman "of Colour" from New Bedford, Hannah H. Smith, and purchased property there as well. In cosmopolitan cities like New Bedford, Pacific Islanders were no longer curiosities to be ogled; they were becoming part of the fabric of the seafaring community.

Seafaring towns, in general, are more cosmopolitan than other towns. I don't think that whalers would literally engage in cannibalism in the streets of Nantucket, say, but the idea that Pacific islanders, Africans, or other people who didn't look like the natives would frequent a port town isn't controversial.