Quart 1948 Cactus Wren April 17 Cerro Prieto 30 ft 20 mi SSE Mexicali, Baja Calif. One heard singing for last hour from top of mesquite tree bordering large flat 75 yds from camp. Song a metallic warble of 4 seconds duration given between 5 second in-tervals. Bird is perched on highest part of tree and lifts head when singing. Preens itself occasionally between songs. When approached bird flew to another mesquite 50yds distant, but returned when I went back to the camp. Bird does not shift position or di-rection during this period of observation. Time 10:40 AM, Temp. 90°F. A sultry day with mild fluctuating breeze & high overcast. From its perch bird can overlook the whole flat, our camp and all of the N side of Cerro Prieto. Bird just shifted position to another twig on top of same tree, looking in opposite direction.