The chances of overhearing a conversation in Vlashki, a variant of Istro-Romanian, are greater in Queens than in the remote mountain villages in Croatia that immigrants now living in New York left years ago.

At a Roman Catholic Church in the Morrisania section of the Bronx, Mass is said once a month in Garifuna, an Arawakan language that originated with descendants of African slaves shipwrecked near St. Vincent in the Caribbean and later exiled to Central America. Today, Garifuna is virtually as common in the Bronx and in Brooklyn as in Honduras and Belize.

And Rego Park, Queens, is home to Husni Husain, who, as far he knows, is the only person in New York who speaks Mamuju, the Austronesian language he learned growing up in the Indonesian province of West Sulawesi. Mr. Husain, 67, has nobody to talk to, not even his wife or children.

“My wife is from Java, and my children were born in Jakarta  they don’t associate with the Mamuju,” he said. “I don’t read books in Mamuju. They don’t publish any. I only speak Mamuju when I go back or when I talk to my brother on the telephone.”