Andy Warhol's silkscreen of a pine-barrens tree frog (pictured above) perched on the edge of a branch captures more than the animal's physiognomy: It shows the critter's place in the world, precarious but clinging, one of several endangered species the pop artist made portraits of in 1983. Almost 20 years later, the battle over the fate of Warhol's subjects is still raging, but somehow his brilliant depictions remind a viewer of the life force behind their existence and not of their imminent loss. Andy Warhol: Endangered Species
, on display at the Ackland Art Museum until Jan. 21, features 10 large, color silk-screen prints that were originally commissioned by longtime political and environmental activists Ronald and Frayda Feldman. Call 966-5736 for details.