K.Selander, 1952 Chordeiles acutipennis August 21 Piede la Cuerta, 20 ft., Guerrero, Mexico - Flushed a single bird (juvenile I think) from lower limb of tree in boggy area. Bird circled once near the ground - lost sight of it. August 23 Flushed a juvenile (possibly same individual) from limb of tree (about 3 feet from ground); flew ± 30 feet and perched on similar branch. Flushed again - this time the bird flew up over the tree & out of sight [?]. Probably perched again some distance from place where flushed). July 18 Valley of the Gila, ±2000 ft., 3 mi. SE Blyes, Graham Co., Arizona Common; flying over the mesquite at dusk. Several were shot (none preserved) including two juveniles which were seemingly fully developed. As darkness approached, the nighthawks flew lower & lower, finally just skimming over the tops of the mesquite bushes. None were seen to fly at high elevations as does C. minor. Flight of C. acutipennis is not as strong as that of C. minor - also less erratic; more direct and slower. Birds silent. Two adult individuals showed partial replacement of the primaries. July 20 San Pedro River, 4000 ft., 25 mi. SE Chihuahua, Chihuahua, Mexico. - 10 individuals flying over river and adjacent fields at dusk. Elevation of flight about 200 feet. July 21 35 mi. SE El Emtronque, 5000 ft., Durango, Mexico. - Two individuals seen flying at dusk.