When people say that proprietor Toni Bishop sings like a bird, they mean it. The jazz singer-turned-restaurateur performs every weekend at her supper club, warbling birdcalls during improvisations. When she's not performing, other national jazz acts like Shirley Horn, Chick Corea, and our perennial favorite, Spyro Gyra, take center stage, which is in the center of a dance floor crowded with tables. Of course no one plays the jazz diva quite as well as Bishop, who just released her second CD, Incredible Love. But you've got to pay for that ear candy. While her performances are free with dinner or drinks, entrées can cost as much as $40. Guest performers' shows, which often sell out, can run you $50. Altogether it can be an expensive evening out. For jazz fans, though, no price is too high to hear such an exquisite bird.