Diet and reproductive biology of the Australian sand-swimming lizards, Eremiascincus (Scincidae)

Abstract

The diets, morphology and reproductive biology of two little-known sand-swimming skinks, Eremiascincus fasciolatus and E. richardsoni, were compared by using preserved museum specimens (n =458). In addition, some ecological data are presented for E. fasciolatus from a mark-recapture study in spinifex grasslands in central Australia. The species are similar in morphology and body pattern, but reportedly differ in microhabitat preferences. Both species ate a range of invertebrate taxa, with beetles, grasshoppers and spiders making up most of the prey consumed. Vertebrate prey (lizards) were rare in the diets but were large and energetically important items when consumed. There were no significant differences in the taxonomic composition of the diets between species, between sexes of a species, or among age classes of a species. Females tended to be longer in body length (snout-vent length, SVL) than males, but adult males were heavier than females of the same body length. Testes of males were enlarged in spring (September-December), coinciding with the appearance of females with vitellogenic follicles. Both species are oviparous, and eggs were laid from October to February. Clutch sizes averaged around four eggs and were not significantly different between the species at the same SVL. Adult E. fasciolatus moved extensively during the field study; average displacement between recaptures was 63.5 ± 128 m. Population estimates for E. fasciolatus varied seasonally between 14 and 108 individuals on the 60-ha study site. E. fasciolatus was most abundant in microhabitats on dune crests with a sparse cover of spinifex but frequently traversed large areas in swales with hard soil and denser spinifex cover.