Movement of the Horned Lizard Phrynosoma solare

Abstract

The movement of the regal horned lizard, Phrynosoma solare, in a desert canyon 4.8 km south of Canyon Lake, Maricopa County, Arizona, was investigated by direct observation and capture-recapture methods from October, 1969 through August, 1970. Five movement patterns (two for adults, three for juveniles) were identified for Phrynosoma solare in normal activity. These movements were all correlated with the activity and stability of their main food source, the harvester ants, Pogonomyrmex rugosus. Adult P. solare either remained for a long period in a small well-defined area close to one or two trails of one or two ant mounds, or exhibited exploratory movements using active ant trails of more than three ant mounds with no apparent tendency to return to the first capture site. Fall hatchlings restricted themselves to a very small, and well-defined home range within one meter of an ant mound entrance, while larger juveniles (55-75 mm in size), during spring and summer, exhibited either a short dispersal pattern of movement, where the lizards left their first capture site and moved to a well-defined range, or a long dispersal pattern, where the lizards wandered within the study area without establishing a definite home range. Adult males averaged 15.32 m between points of capture and had a mean maximum distance between points of capture of 30.66 m, whereas females were more restricted in their movements and averaged 7.88 mm between points of capture and had a mean maximum distance between points of capture of 14.80 m.