Two Tucson libraries celebrate Tucson's Birthday with presentations by Arizona-Sonora Desert Museum staff about predators and prey in the surrounding desert. Presentations are from 3 to 4 p.m., Thursday, Aug. 18, at Martha Cooper Branch Library (1377 N. Catalina Ave.; 594-5315); and from 1 to 2 p.m., Saturday, Aug. 20, at Himmel Park Branch Library (1035 N. Treat Ave.; 594-5305). Free. Call for more information. Visit tucsonsbirthday.org for a calendar of all related events.