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Soil-disturbing animals play a critical role in many ecosystem processes. The loss of native soil-foraging mammals (e.g. greater bilby Macrotis lagotis; burrowing bettong, Bettongia lesueur) throughout vast areas of Australia has altered fundamental soil processes such as decomposition. Little is known about whether surviving native soil-disturbing animals (e.g. short-beaked echidna, Tachyglossus aculeatus) produce soil disturbances that are functionally equivalent to those of locally-extinct native animals. We used a litter bag study to compare abiotic and biotic mechanisms of decomposition within the foraging pits of two native mammal species. We compared decomposition rates between landforms, which we used as a surrogate for soil texture; grass species Austrostipa scabra subsp. scabra and Triodia scariosa subsp. scariosa, which we used as our substrates; and the effects of chemically excluding fungi and/or termites. There were initial differences in the organic mass loss between echidna and bilby/bettong foraging pits, with bilby/bettong pits losing more over 30days, and echidnas losing more over 63days. However, over 396days there was no significant difference between the two pit types. Landform (soil texture) and chemical exclusion of termites and fungi did not affect our measures of decomposition until the final stage of the study. The two grass species lost significantly different amounts of organic material at each collection interval, with Austrostipa losing more at 30, 63 and 130days and Triodia losing more at the final 396day collection. This provided the most consistent effect on decomposition. Our results highlight the temporal idiosyncrasies in the various drivers of decomposition in this dune-swale system. Overall, this study provides evidence that the foraging pits of the short-beaked echidna do not differ markedly from those of the locally extinct greater bilby and burrowing bettong in terms of their capacity to maintain rates of decomposition at an annual scale. Copyright (c) 2015 John Wiley & Sons, Ltd.