Phenology of a lizard assemblage in the dry chaco of Argentina

FITZGERALD, L.A.; CRUZ, F.B.; PEROTTI, M.G.

JOURNAL OF HERPETOLOGY

Society for the Study of Amphibians and Reptiles

Año: 1999 vol. 33 p. 526 - 535

0022-1511

Individual species´ phenologies can play an important role in the structure of lizard assemblagesover short time scales. Data from a pitfall study carried out in the dry Chaco of Argentina were usedto address the question of how species are distributed in their assemblage through time. Lizard activity andspecies richness were highest in the spring breeding season and declined in the cool months of the year.Variations in seasonal activity patterns and reproductive chronology resulted in significantly different distributionsof species in every sample month. Not only did the species composition of the assemblage changethrough time, but the mean size of lizards and the proportions of males, females, and juveniles variedsignificantly for several species. Large lizards, regardless of species, disappeared from the assemblage duringthe cool, dry winter, while juveniles of the large species remained active year round. Adults of the smallestspecies were also active throughout the year. We propose an hypothesis based on thermoregulatory constraintsof lizard body size to account for these patterns. An approach focusing on the energetics and physiologicalecology of individual species would be fruitful in understanding the dynamics of fluctuating lizardcommunities.