Ford 2879 Gymnogyps californianus February 12, 1946 Hopper Canyon Ckt. Rim + 1000± above it. This bird circled 5+ min- utes above Parking Knoll area, then glided across canyon until 1000± over E. Rim, then slowly spiraled down in Big Cave vicinity (4:04). About 3:50 saw a second adult over W. Rim near me - it headed into Hopper Basin when at 500± alt. Yet another seen gliding toward Big Cave area from E. at about 4 p.m. The one which took the long trip (adult) had no apparent flight feather deficiencies. Soaring made a light sing- ing sound. No flaps were seen, but several dips + half dips. Some turns in circling were made without me wing tip dipping first, & some with (usual). Leading edge of wing very straight in soaring - no nuckle visible at wrist. The air is apparently good for soaring though no air motion is apparent on Hopper Rim & there is a heavy gray haze at about 3500 ft. level. Drove toward Old Cabin until I got a good view of Big Cave - saw at least 12-14 there at 4:25. One sunned, looked to swim. None at pool. 3 in top branches of Roost Tree. From Old Cabin at 4:33 counted 22 con- ders at Big Cave area. 4± were within 10±' of the pool atop the falls but did not seem to drink. Still much shifting between roasts but some birds flattened (202) out in roosting position (1 on a top branch of Roost Tree).