This is a photo of an Iroquois Indian—So-Tsien-O-Wa-Ne or Big Chief Great Fire—patrolling the lake in Central Park in 1925. Why? The Getty caption reads that his job was "to glide around the lake, preserve order, and lend colour."
A NY Times article (via Ephemeral NY) from April of that year goes into further detail, reporting that he "is to glide hither and thither around the three-mile stretch of water, preserve order, and lend local color." They add that "he has lived for some years in Brooklyn, although born on a reservation in Montreal. On duty, Chief Great Fire will be attired in the usual buckskin clothes with plenty of feathers attached."
We've reached out to the Parks Department for more information on the stunt, which wouldn't have been historically accurate, of course, because Manna-hata was Lenape territory.