Patelka 1946 Cathartes aura Oct. 10 Observed frequently from Nogales south to Mazatlán; less and less common southward, however, and outnumbered appreciably by Coragyps at Mazatlán. Oct. 16 El Batel, 70 km. NE Mazatlan, 5100 ft., Sinaloa Common here, soaring scatteredly, especially along the ridges, when they clear partially. Found to be increasingly common as we moved from Mazatlán upward into the mountains. Oct 31 Pitahaya, 40 km. SE Empalme, 100 feet, Sonora Common, about 5 or 6 times as numerous as Coragyps.