It’s not surprising that the major studios are scaling back on literary adaptations.

For one thing, there are fewer pics overall.

“The business has gotten much tougher for everyone, because there are so many fewer studio films,” says Marshall Herskovitz, who’s wrapping up four years as prexy of the Producers Guild of America. “Generally, studios only want to make tentpoles now, so that means there’s not a lot of interest in other films.”

That tentpole mindset certainly skews everything in Hollywood: Among the six studios, 30% of the films on their upcoming schedules are either sequels or remakes.

Sequels account for one-third of Warner Bros.’ 2011 sked. Of the 18 Disney pics with release dates, seven are franchises. Paramount and Fox have the highest percentage of their upcoming slates filled with sequels and remakes, each around 40%. Universal and Sony have the fewest franchise properties, with four apiece.

That compares with a grand total of a dozen pics that could be classified as adult-targeted — an average of two films per studio.

Hollywood execs believe franchise films are pre-sold — a particularly important attribute in most international markets. Execs say per-capita moviegoing in foreign markets lags behind the rate in the United States, and customers are more inclined to spent their euros, yen or pesos on a film they recognize.

WB’s franchise sked for next year: “The Hangover 2” (bowing May 26), the second part of “Harry Potter and the Deathly Hallows” (July 15), “Happy Feet 2” (Nov. 18) and “Shelock Holmes 2” (Dec. 16) as well as a trio of New Line franchises: “Final Destination 5” (Aug. 26), “Journey to the Center of the Earth 2” (Sept. 23) and “New Year’s Eve,” a spinoff from “Valentine’s Day” (Dec. 9).

Warners also has set the third Batman pic directed by Christopher Nolan for July 20, 2012, even though the project has yet to be officially greenlit.

Par’s schedule for the rest of this year includes “Jackass 3D,” the “Paranormal Activity” sequel and “True Grit”; the 2011 schedule includes a “Kung Fu Panda” sequel, “Transformers 3,” Shrek spinoff “Puss in Boots” and “Mission: Impossible 4.” It’s also set “Madagascar 2” for 2012.

Upcoming for Disney are a third “Toy Story,” a fourth “Pirates of the Caribbean” and “Tron: Legacy.”

U’s slate includes the third “Meet the Parents” pic, “Little Fokkers”; Sony’s already set “Men in Black 3” for 2012.

Meanwhile, adult dramas greenlit or with looming release dates include:

Paramount: “True Grit.”

Sony: “The Social Network,” “How Do You Know”

Disney: “Secretariat”

U: “The Dark Fields,” “Charlie St. Cloud”

WB: “The Town,” “Something Borrowed” (Alcon), “The Rite” (New Line), “Hereafter”

Fox: “Wall Street 2,” “We Bought a Zoo”