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Even apparently subtle disturbance to habitat may have severe long-term consequences if that disturbance alters specific microhabitat features upon which animals depend. For example, in south-eastern Australia, the endangered broad-headed snake Hoplocephalus bungaroides and its prey (velvet geckos Oedura lesueurii) shelter in narrow crevices beneath sun-warmed rocks. Humans frequently displace rocks while searching for snakes and lizards, and these reptiles are rarely found under such displaced rocks (even when the rocks superficially appear suitable). We quantified disturbance to rock outcrops and show that most disturbance was subtle (rocks were typically displaced <30 cm from their original position), but that disturbed rocks harbored fewer reptiles than undisturbed rocks. In a field experiment, we replaced half of the rocks back to their original positions to test whether crevice structure and microclimates differed between disturbed and restored rocks. Crevices beneath displaced rocks were larger and cooler than those beneath restored rocks, and precise repositioning of rocks enhanced usage by reptiles. Both crevice size and temperature influence reptile retreat-site selection; hence, minor displacement of overlying rocks reduces habitat quality by modifying critical crevice attributes. The subtlety of this disturbance suggests that even well-intentioned researchers could damage habitat during field surveys. Conservation of rock outcrop systems requires efforts to reduce rock disturbance, and to educate those searching for animals beneath rocks about the importance of replacing rocks properly. Encouragingly, if rocks are not completely removed, disturbed outcrops can be quickly and easily restored by returning displaced rocks to their original locations. [ABSTRACT FROM AUTHOR]

Abstract Background To conserve critically endangered predators, we also need to conserve the prey species upon which they depend. Velvet geckos (Oedura lesueurii) are a primary prey for the endangered broad-headed snake (Hoplocephalus bungaroides), which is restricted to sandstone habitats in southeastern Australia. We sequenced the ND2 gene from 179 velvet geckos, to clarify the lizards’ phylogeographic history and landscape genetics. We also analysed 260 records from a longterm (3-year) capture-mark-recapture program at three sites, to evaluate dispersal rates of geckos as a function of locality, sex and body size. Results The genetic analyses revealed three ancient lineages in the north, south and centre of the species’ current range. Estimates of gene flow suggest low dispersal rates, constrained by the availability of contiguous rocky habitat. Mark-recapture records confirm that these lizards are highly sedentary, with most animals moving Conclusion The low vagility of these lizards suggests that they will be slow to colonise vacant habitat patches; and hence, efforts to restore degraded habitats for broad-headed snakes may need to include translocation of lizards.