E. Aldreck 1938 pitch, and whole song lasts about 4 seconds, repeated averaging 10 sec intervals. Another similar song heard behind me. After shot, saw nor heard them any more. Head was entirely slate gray, bill light, almost white, end with much rufous on back. Was not Black-chinned Sparrow as have heard them & seen them before. Was a Sincer of some sort that had no black at base of bill. May 26, 1938 In AM went down wash of Cedar Canyon to spent photographing Gray Vireo again and others. In afternoon walked farther down wash nearly to Pinnacle close to CH Thomas ranch. Observations of note for today: - Rattlesnake - With Rodgers in AM, saw small rattler attempting injecting of Cerogenus longimbris in sunshine beside Artemisia bush. Rattles so small that noise made by snake was very high pitched & corresponding higher frequency. Attempted to photograph, but snake regurgitated. - Cedar Waywing - saw and attempted to collect a 8 singing Stop Chilopsis tree. - Cedar Waywing - saw two and collected one from same Chilopsis as above.