Birds do it, bees do it, even big ol' manatees do it ...

TAMPA, Fla. — Genevieve Chandler has been visiting the Lowry Park Zoo since she was a kid, but the tour she got the other night was definitely not the G-rated fare of her childhood.

Among the things Chandler, 30, and her date learned on their "Wild at Heart" zoo tour: Male pigs have a unique corkscrew endowment and impressive, um, output; manatees have orgies and don't really care if their partners are male or female; and a male porcupine has only one four-hour window a year to mate — very carefully, of course.

Valentine's Day is the time of year when zoos around the nation seek to woo a new adult audience with risque tours that couple champagne, chocolate-covered strawberries and candlelight dining with impressive facts about how animals do the wild thing.

Credit for the concept goes to Jane Tollini, a former penguin keeper at the San Francisco Zoo. Tollini conceived the idea two decades ago while watching her penguins' courtship ritual, which culminates in what she describes as "bowling pins making love."

"The keepers get there early and we see things that other people don't see," Tollini said. "And I went, 'My God, that's fascinating.' "

She set the ritual to Johnny Mathis — the makeout tunes of her generation — pitched it to her bosses and a new zoo tradition was born. The idea soon spread to other zoos.

San Francisco calls it "Woo at the Zoo." New York City's Central Park Zoo calls it "Jungle Love." Zoo marketing folks in Boise, Idaho, named the tour "Wild Love at the Zoo."

Zoos charge about $50 per person for the tours, and crowds are kept deliberately intimate. Many zoos, including Lowry Park, have added additional nights to handle Valentine's overflow.

"It's a fundraiser, but it's definitely not our largest," said Rachel Nelson, Lowry Park's director of public relations. "It's a way to introduce a new audience to the zoo."

Tollini puts it more bluntly: "Sex sells."

However, zoo sex tours tend to be all talk and no action. Animals do it when they please, or, in some cases, when their human keepers deem it appropriate.

Tour guides in Tampa warned of possible manatee makeout sessions. But the giant mammals were content to munch on vegetation while the tour group ate a candlelight dinner in front of the zoo's massive aquarium windows.

"Manatees are not particular," Nelson said. "We have only males right now and they don't seem to care."

Despite the blunt talk on the tour, many in the Saturday crowd in Tampa were coy about their reasons for attending.

"I really like the zoo and I thought it was a nice thing to do with my boyfriend for Valentine's Day," Chandler said.