SANTA CLARITA, Calif. — Wildlife officers on Wednesday were tracking a mountain lion that attacked a 7-year-old boy and prompted the closure of a sprawling Southern California park, authorities said. The child and his father were walking up stairs at Pico Canyon Park near Santa Clarita around dusk on Monday when a cougar emerged from brush and bit the boy on the buttocks, said Capt. Patrick Foy with the California Department of Fish and Wildlife. Foy said the father, who was walking behind, heard his son cry out and charged toward the big cat. “The lion let go and retreated...