Hullion 1949 Passercella iliaca Sept 9 Red Mtn, 5300 ft, 14 mi S Hayfork, Trinity Co., Calif. overlooked these birds until today. Before the heat of the day began and as long as I worked slopes which the sun had not yet really begun to boil down on I found these birds very common, with each isolated clump brush group having at least one bird, and groups of several occupying the larger brush areas. But about 11 a.m., working thru the same areas after the sun had been on them for 1 or 2 hours, and it was getting warm, these fox sparrows had completely vanished and gave absolutely no clue to their presence.