Hardwickson 1950 Pipistrellus hesperus Aug. 24 Lower Corning Plate, 3000 ft., Riverside Co., Calif. disappear, seemingly without pause, into a crack in the rocks. At 9:45, when I left, I went to the crack where the bat disappeared, found it and collected it alive. Experimented with various whistles, squeaks, etc., to see if there was any noticeable effect on the bats. During this time, I laid my loud-ticking pocket watch on a rock ledge nearby; almost immediately three bats appeared and fluttered close as if investigating the sound. Repeated removal & return of the watch produced no results.