Shelter-site use by five species of montane scincid lizards in south-eastern Australia

Abstract

Montane (cold-climate) habitats may impose severe thermal constraints on habitat use by ectotherms, favouring strong interspecific convergence in the attributes of suitable shelter-sites. We studied shelter-site use by five species of viviparous scincid lizards in Kanagra Boyd National Park, a montane (1200 m above sea level) forested region 160 km west of Sydney. We scored 21 attributes of 93 shelter-sites (13–20 per species), and the same attributes at unoccupied 'control' sites. These attributes included macrohabitat (e.g. canopy openness, substrate type, distance to waterbodies and logs) as well as shelter-site characteristics (e.g. type of cover-item, size of crevice). Hemispherical-lens photographs and gap-analysis software yielded estimates of solar radiation at each site, and data-loggers recorded temperature profiles in each occupied retreat-site. Principal Components Analysis of the data set identified eight axes of variation. Significant interspecific differences were evident on four of these axes, but with substantial overlap reflecting the broad syntopy of the taxa, plus similarities in characteristics of occupied retreat-sites (e.g. most lizard species utilised sun-exposed shelter-sites with logs nearby). Egernia species (cunninghami, saxatilis, whitii) typically used more open habitats than did Eulamprus (heatwolei, tympanum). Egernia cunninghami used very large crevices, whereas Eulamprus tympanum occupied heavily wooded macrohabitats. At this cold-climate site, interspecific similarities in the characteristics of utilised retreat-sites generated substantial overlap among species in the kinds of sites used, potentially intensifying interference competition among these taxa.