We compare bias in the interpretation of sampled reptile and mammal assemblages caught using 20-L PVC buckets and PVC pipes ( 150 mm by 600 mm deep) when used as pit-traps. We report on 16632 pipe- and 16632 bucket-nights of pit-trap data collected over 11 survey periods spread over 2.5 years around Ora Banda in Western Australia. Buckets caught more reptiles and more of the common 'small' and 'medium'-sized reptiles, whereas pipes caught more mammals and the larger of the small trappable mammals. The trappability of some families of reptiles and some mammal species differs between buckets and pipes. We conclude that different pit-trap types provide a bias in the interpretation of the sampled fauna assemblage. Differences in the interpretation of vertebrate faunal diversity were accentuated by low trapping effort but attenuated by high trapping effort. We recommend that both buckets and pipes be employed as pit-traps during fauna surveys ( as well as alternatives such as funnel traps) to more fully document fauna assemblages being surveyed.