Daily and seasonal activity patterns of a lizard guild in the sand dunes of Viesca, Coahuila, Mexico

Abstract

IN 2002, DAILY AND SEASONAL ACTIVITY PATTERNS OF THE LIZARDS UTA STEJNEGERI, UMA EXSUL, AND ASPIDOSCELIS MARMORATA WERE EVALUATED IN A DUNE HABITAT IN THE SOUTHWESTERN PORTION OF COAHUILA, MEXICO. METHODS INCLUDED SURVEYING A 500 M TIVITY PATTERNS OF THE LIZARDS UTA STEJNEGERI, UMA EXSUL, AND ASPIDOSCELIS MARMORATA TRANSECT ONCE PER HOUR BETWEEN 0700 AND 1900 FOR 7 DAYS EACH SEASON DURING THE SPRING, SUMMER AND FALL. THE NUMBER OF ACTIVE LIZARDS, AIR AND SUBSTRATE TEMPERATURES, AND RELATIVE HUMIDITY WERE RECORDED. A STANDARDIZED LEVINS INDEX AND PIANKA´S METHOD WERE USED TO MEASURE TEMPORAL NICHE BREADTH AND OVERLAP, RESPECTIVELY. IN EACH OF THE 3 SEASONS, U. STEJNEGERI WAS ACTIVE EARLIER THAN U. EXSUL, AND U. EXSUL WAS ACTIVE BEFORE A. MARMORATA. THE 3 SPECIES SHOWED A BIMODAL ACTIVITY PATTERN DURING SPRING AND SUMMER, AND UNIMODAL IN FALL. ASPIDOSCELIS MARMORATA SHOWED THE SMALLEST NICHE BREADTH IN THE 3 SEASONS. FOR EACH SPECIES, PREFERRED BODY TEMPERATURE AND ENVIRONMENTAL TEMPERATURE SEEM TO DICTATE ACTIVITY PATTERNS OF THIS LIZARD GUILD AT VIESCA.