I suspect they are. They’re a collection of about a dozen houses along Woodycrest Avenue, where it’s crossed by 164th Street, in the South Bronx.
Some NYC history: before 1898, Brooklyn was a separate city, and Queens was a collection of separate municipalities. Staten Island was (and remains) a separate universe. But the Bronx was the organic extension of New York City’s development beyond Manhattan: along with Manhattan, it comprised the City of New York before the greater, five-borough city was legally formed. Evidence of the close relationship between Manhattan and the Bronx is still visible in the continuity of street and house numbering from one to the other; the continuities of Broadway, Park Avenue, and Third Avenue between the boroughs; and the fact that no ZIP code in the Bronx ends in the same two digits as any in Manhattan, due to the borough’s historic coverage by the “New York, New York” post office.
So, onto detached Victorian houses. There was probably a time when New York City proper had a large stock of detached Victorians, like those that remain in San Francisco or Boston, or the ones in the above picture. (Brooklyn, Queens, and Staten Island, of course, all have their fair shares of such houses.) But Manhattan and the Bronx grew faster in the late 19th and early 20th centuries than any of those places, and most of their formerly low-density sections were completely built up with tenements and apartment buildings by the 1920s– long before historic preservation was an urban planning concept. As a result, the stock of detached Victorians in New York City proper is almost totally erased.
Manhattan– the heart of the city proper– has barely any detached houses remaining, at all. (There are literally three or four on Park Terrace West and a couple on Seaman Avenue, in Inwood, and a few in Marble Hill.) The Bronx, on the other hand, has probably tens of thousands of detached houses, but most of them are simple wood-frames, Tudors, colonials, or brick duplexes that post-date the Victorian period. In light of the historical context, this bunch of spacious homes with turrets, gables, and wraparound porches on Woodycrest Avenue is unique. And it may actually be the last remnant of an architectural period in the city’s history that has all but disappeared.
Will research more, and update.
Update: there is a handful of smaller detached (possible) Victorians, much less elaborate, in Marble Hill.