Summary The impacts of uncapped, abandoned mining shafts on small vertebrate species were investigated by monitoring numbers of fauna falling into opal prospecting shafts near Coober Pedy, in the far north of South Australia. Catching devices made from 10 L buckets were installed in the top of 43 shafts and checked regularly by local community members for a total of 10 840 trap nights over a 13-month period. A total of 190 individual reptiles of 18 species were captured in this manner after falling into shafts, including the nationally vulnerable Bronzeback Legless Lizard (Ophidiocephalus taeniatus). While the tops of these shafts resemble conventional pitfall traps used in scientific monitoring and therefore readily ‘trap’ ground-fauna, they may be over 30 m deep and are permanently open. Capture rates in this study, calculated at 4.1 reptiles/shaft/year, highlight the potential impact of the similar shafts that remain uncapped in the Coober Pedy opal fields, roughly estimated to be anywhere from 1 to 2 million shafts. The inferred total number of captures from these shafts may represent 10–28 million reptiles/year or an equivalent of 25–72 tonnes of biomass. The results highlight the potential threat that uncapped shafts may pose to Bronzeback Legless Lizard populations in this area and suggest that they may also have major impacts on other small vertebrate fauna in the Coober Pedy area and in other similar opal mining areas.