DENSITY, GROWTH, AND HOME RANGE OF THE LIZARD UTA STANSBURIANA STEJNEGERI IN SOUTHERN DONA ANA COUNTY, NEW MEXICO' Richard D. Worthington-and Edward R. Arvizo'^ Abstract. — Side-blotched lizards. Uta stansburiana, were marked and re-captured on a study plot near Anapra. Dona Ana County, New Mexico, during the suiTuner of 1971. The density in July was estimated to be 20.3 individuals per acre (50.2 per hectare). The home range size for males averaged 0.254 acres and for females, 0.097 acres. Males 48-53 mm s-v increased 0.034 mm/day in s-v length and 0.067 mm/day in tail length from middle .July to early Septem-ber. Females 41 .5-46 mm s-v increased 0.028 mm/day in s-v length and 0.058 mm/day in tail length during the same period. During the past hundred years the vegetation of southern New Mexico has changed from a desert grassland climax to a desert climax (York and Dick-Peddie, 1969). Presumably, there have been major changes in the composition of the vertebrate fauna and the relative abundance of different species. Preliminary investigations of the lizard fauna on a study plot located near Anapra, Dona Ana County, New Mexico, were begun during the summer of 1970 in order to determine species composition, relative abundance, and other eco-logical parameters of the different populations. Data gathered on Uta stansburiana stejnegeri during the summer of 1971 have been analyzed and are presented and compared with the results of other investigators. Methods A study plot measuring 100 yards to a side (10,000 sq yd; 2.07 acres) was constructed on the morning of 18 July 1971 and marked with numbered and lettered stakes at 50 ft intervals forming 36 quadrats. Observations were begun on the same afternoon. The study plot was worked by two observers on 14 visits and by one observer on two visits through 29 July. Lizards were collected by noosing and marked by toe clipping. Numbers were painted on the backs of lizards with a water-base paint to facilitate recognition with a minimum of recaptures. The point at which the lizard was first seen was noted, and the number of feet to the nearest stake recorded in order that the home range could be reconstructed. The sex, snout-vent length, tail length, and length of any regenerated portion of the tail was determined for each lizard at the time of first capture. We attempted to estimate density by marking all individuals on the study plot and have followed Tinkle and Woodard (1967) in considering individuals as residents if most of the capture points were within the study plot. The study plot and its immediate periphery were patrolled in different patterns to avoid biasing the observations. 'Contribution No 4 from the Museum of Ariel Land Biology, University of Texas at El I'a9f>. ^Department of BioloRiral Sciences, University of Texas at El Pasn. El Paso. Texas 7^008. 'Depaitmrnt of /oolnny, Utali Slate University. Logan. ITtali R\\l\ . 124
BioStor
