A capture-recapture study on the murid rodents, Melomys cervinipes and Rattus fuscipes, was carried out in a sub-tropical Queensland rainforest from July 1969 to April 1971. This was done in order to determine the types of environment experienced by the two species, and to compare their life history and population characteristics. M.cervinipes was found to use nearly all the substrate provided by the rainforest, while R.fuscipes concentrated its activity in patchily distributed areas of high ground vegetation density. During a seasonal peak in the abundance of fruit and arthropods, R.fuscipes increased the proportions of these foods in its diet. The diet of M.cervinipes, green leaves mixed with a smaller amount of fruit, did not appear to change during the year. R.fuscipes appeared to experience an environment that was spatially and temporally variable and unpredictable. The experienced environment of M.cervinipes appeared to change little in space and time.
Breeding of both species was seasonal, with M.cervinipes starting earlier, and finishing later, than R.fuscipes. M.cervinipes had litters of either one or two young, and R.fuscipes had a mean litter size of 5. M.cervinipes become sexually mature at 4 to 6 months, R.fuscipes at 3 to 4 months. After an initial period of rapid growth, growth of M.cervinipes is slow and constant. Growth of R.fuscipes occurs in two separate bursts; one during the first few months of life, the second during their first breeding season. M.cervinipes live for anything up to two to two and a half years, R.fuscipes usually die soon after they are a year old. The M.cervinipes population remained relatively constant in size, and there was little turn-over of individuals. R.fuscipes population was characterized by fluctuations in size and a large turn-over of individuals.
R.fuscipes life history allows for the rapid production of large numbers of young over a short period of time, during which there is a seasonal abundance of food. This production of a large number of young, together with the periodic reshuffling of individuals in the population, seem geared to ensuring the colonization of the temporary patches of dense ground vegetation. The life history of M.cervinipes incorporates patterns of reproduction and growth that seem geared to minimizing fluctuations in the pressure it exerts on its minimally fluctuating resource level.