DIET AND HABITAT USE OF FRILLNECK LIZARDS IN A SEASONAL TROPICAL ENVIRONMENT

A population of frillneck lizards, Chlamydosaurus kingii, was monitore d by mark-recapture and telemetry over a 2 year period in Kakadu Natio nal Park. The aims of the study were to document changes in diet, grow th, condition and habitat use between the wet and dry seasons of north ern Australia, in light of recent research examining seasonal variatio n in the physiology of this species. Frillneck lizards feed on a diver se range of invertebrates in both seasons, even though there is a subs tantial reduction in food availability in the dry season. Harvester te rmites from the genus Drepanotermes constitute a major component of th e diet, and the prevalence of termites in the diet of sedentary forage rs in a tropical environment is unusual. Adult male body condition rem ained relatively stable throughout the year, but females experienced c onsiderable variation. These differences are attributed to different r eproductive roles of the sexes. Growth in C. kingii was restricted to the wet season, when food availability was high, and growth was minima l in the dry season when food availability was low The method used in catching lizards was an important factor in determining seasonal habit at use. Telemetered lizards selected a significantly different distrib ution of tree species than was randomly available, and they selected s ignificantly larger tree species during the dry season. Lizards spotte d along roadsides showed little seasonal variation in the selection of tree species or tree sizes. The results suggest a comprehensive chang e in the ecology of this species, in response to an annual cycle of lo w food and moisture availability, followed by a period with few resour ce restrictions.