The areas with zero park-sex tickets recorded over 10 years were some with little to no park space to speak of — Midtown Manhattan; Jackson Heights in Queens; Canarsie in Brooklyn — and others like the central Bronx neighborhoods of East Tremont and Belmont, where there are parks but, apparently, no sex seen by officers.

The act — considered a violation of park rules that currently carries a $100 fine — has to be witnessed by an officer for any action to be taken.

“You walk through the park and see a guy leaning against a tree: What crime is being committed there?” said Officer Bryan Polster, whose assignment includes Fort Tryon Park. “Just to be meeting someone in the park is not a crime. And I think that’s why the complaints are nonexistent.”

His precinct once topped all others for criminal tickets for park sex, with 81 tickets in 2007. The area contains several large parks, including Fort Tryon’s bucolic green space with sweeping Hudson River views and several wooded areas that have long been known as cruising spots, particularly for gay men.

In Fort Tryon, city officials met with residents in 2015 about the public-sex displays, and came up with a preventive strategy: A chain-link fence was installed to block access to the popular hidden spot; nearby, overgrown plantings cover another area that had drawn complaints.

In Harlem’s Marcus Garvey Park, residents in a towering condominium across the street on Fifth Avenue have long complained about their view of “the mountain” — a rocky rise of New York schist about 70 feet high where people meet for sex or to use drugs.