It was time for the annual Valentine's Day sex tour at the San Francisco Zoo, but none of the permanent residents got the memo. As human voyeurs learned about the torrid world of amorous beasts, most of the animals barely glanced at each other. "The wind seems to unnerve them," said Jane Tollini, inventor of the tour that has been copied by zoos throughout North America. "And they had a busy weekend." They did indeed. Tollini, former penguin keeper at the zoo, led excursions Saturday and Sunday and will do the same this weekend. She came up with the idea...