Subhabitat variability: A key to the high reptile diversity in chenopod shrublands

The herpetofauna of one hectare of chenopod shrubland near Roxby Downs in arid South Australia was studied from January 1991 until June 1993. The subhabitat preferences of 27 reptile species and one frog species were investigated by analysing capture rates, from more than 1800 captures in 401 pit traps. Although the site was characterized by relatively uniform cover of the dominant plant species Atriplex vesicaria , significant variation occurred in rock cover, and in edaphic and floristic features. Ctenophorus fordi, Ctenotus brooksi and Lerista labialis were strongly associated with sandy regions while Tympanocryptis intima, Diplodactylus tessellatus and Ctenotus strauchii were largely restricted to rocky subhabitats. Ctenotus leonhardii was strongly associated with a high density of Maireana species. Subhabitat preference of some of these species could be explained by the defence strategies they employed. Several species such as Ctenophorus nuchalis, Pogona vitticeps, Tympanocryptis lineata, Diplodactylus stenodactylus, Rhynchoedura ornata, Menetia greyii and Neobatrachus centralis were subhabitat generalists within the study site. The biological appropriateness of using a smaller number of subhabitat groupings, rather than the square root of the number of study sites, was confirmed in this study. Five subhabitat groups yielded meaningful preference data for more species than did 10 or 20 groups, and did not lose resolution achieved through higher level clustering.