Influence of shade covers on pitfall trap temperatures and capture successof reptiles and small mammals in arid Australia

Shade covers for pitfall traps can be used to reduce the amount of solar ra diation penetrating to the bottom of pitfall buckets, thereby reducing the number of captured animals dying from heat-stress. We tested the effectiven ess of a variety of shade covers for reducing temperatures in pitfalls and trap mortality of small vertebrates, and examined the effect of one cover d esign on trap success in arid landscapes. Shade covers made of insulation f oil were found to reduce core pitfall temperatures by 20-22 degrees C compa red with uncovered buckets, which reached temperatures greater than 66 degr ees C. Other cover types tested (plastic lid or cardboard) were found to be less effective: core bucket temperatures still reached 48-53 degrees C. Wh ile foil covers do reduce temperatures and therefore the probability of hea t-stress-related mortality, above-ground foil covers also influence trap su ccess. Traps with above-ground foil covers caught 39-43% fewer small verteb rates and 7-42% fewer species than uncovered traps. Above-ground foil cover s had the greatest influence on the sampled abundance of scincid lizards (r educed by 50-52%), reduced the sampled abundance of most other lizard famil ies and mammals, but increased capture success for snakes. If shade covers are required to minimise heat stress and mortality in pitfall buckets we re commend foil covers placed inside the bottom pitfall buckets as they signif icantly reduce pitfall temperatures and are likely to have minimal influenc e on trap success. However, regular checking of traps is still one of the m ost reliable ways to reduce heat-stress-related and other deaths in pitfall traps.