The Jonas brothers’ new sitcom premiered on the Disney Channel Saturday, providing another intriguing reminder that there’s riches in niches — in this case, girls age 9 to 14.

Jonas Disney noted that the show delivered 1.6 million viewers in that age group, known as “tweens,” and a respectable 4 million overall. (By the way, any adults watching the program without a child present should be immediately placed on a watch list.)

The more interesting statistic, though, is that 75% of those tweens were girls, meaning they outnumbered boys three to one. The percentage was exactly the same among the younger demographic breakdown of kids age 6-11.

So while Cartoon Network has made solid in-roads with boys thanks to “Star Wars: Clone Wars,” and other competitors — including off-shoot channels like Nickelodeon’s Nicktoons and Disney XD — join an increasingly crowded scrum for boys, girls remain an extremely lucrative niche, especially if their “Jonas” viewing yields the expected appetite for Jonas brothers music and merchandise.

What’s perhaps most interesting is that these various kid-oriented cable networks are going after each other in take-no-prisoners fashion, recognizing that they’re pursuing a finite children’s market that the major networks have essentially abdicated to them.

Tweens, in fact, represent just how heated the battle has become, inasmuch as it’s a relatively new demographic segment, minted by Disney to differentiate itself from younger-skewing rivals. Once you start splitting up the pie among preschoolers (age 2-5) and kids (either 2-11 or 6-11) and tweens (9-14), the spinning is enough to make your head spin.

Cutting through that haze, it seems fair to say that the Jonas trio has gotten off to a reasonably promising start in their ongoing quest to sing for their supper — and in the process to separate your female children from their allowances.