Large rain events drive dramatic resource pulses and the complex pulse-reserve dynamics of arid ecosystem changes between high-rain years and drought. However, arid-zone animal responses to short-term changes in climate are unknown, particularly smaller rain events that briefly interrupt longer-term drought. Using arthropods as model animals, we determined the effects of a small rain event on arthropod abundance in western NSW, Australia during a longer-term shift towards drought. Arthropod abundance decreased over two years, but captures of ten out of fifteen ordinal groups increased dramatically after the small rain event (<40mm). The magnitude of increases ranged from 10.4 million% (collembolans) to 81% (spiders). After three months, most groups returned to pre-rain abundance. However, small soil-dwelling beetles, mites, spiders, and collembolans retained high abundances despite the onset of winter temperatures and lack of subsequent rain. As predicted by pulse-reserve models, most arid-zone arthropod populations declined during drought. However, small rain events may play a role in buffering some groups from declines during longer-term drought or other xenobiotic influences. We outline the framework for a new model of animal responses to environmental conditions in the arid zone, as some species clearly benefit from rain inputs that do not dramatically influence primary productivity.