As a part of a life history study on the Nelson antelope ground squirrel, Ammospermophilus nelsoni , observations on age, home range and dispersal were started in 1947 and continued until approximately June, 1956. The area live-trapped is 65 miles west of Fresno, California, the home base, and located where rainy weather makes the road impassable. Most time was available during the summer when heat made live-trapping hazardous for the squirrels. During most of the other nine months only week ends were available for work. This resulted in gaps in the data, but sufficient material is available to cover the points discussed. The field work, which includes this study, was supported in its later stages by U.S. Public Health Service Grant E-723. Plants have been identified by Dr. C. H. Quibell of Fresno State College; the drawings are the work of Mr. George C. Jensen of San Francisco, California. Area description .—The area trapped (Fig. 1, Plate I) is located 6 miles east of Panoche, San Benito County, California (Panoche Quadrangle, edition of 1913, reprinted 1924, U.S.G.S.) at an elevation of approximately 1200 feet. This would fall within the “Valley Grassland” vegetation type of Munz and Keck (1949), but more exactly is a variant of this, containing such plants as joint-fir ( Ephedra calif ornica ), California juniper ( Juniperus californiens ) and snakeweed ( Gutierrezia calif ornica ). Perennial poa ( Poa scahrella ) and the annuals red brome ( Bromus ruhens ) and red-stemmed filaree ( Erodium cicutarium ) make up the bulk of the herbaceous vegetation. Fig. 1 Map of study area. Numbers correspond to those on succeeding figures. Plate.1 The study area. Picture taken looking west from Point 3, Fig. 1. Rainfall averages around 5 inches, but may run up to 10 inches. The area is a desert in character, both in plant constituents and animal species. A …