Synchronous boom-bust cycles in central Australian rodents and marsupials in response to rainfall and fire

Abstract

Understanding the impacts of rainfall and fire on the population dynamics of mammals in desert ecosystems has been hampered by a lack of long-term data. In this study, we use a 16-year data set to investigate these relationships in an assemblage of 8 small rodents and dasyurid marsupials in central Australia. We hypothesized that marsupial populations would be less variable and less responsive to rainfall than rodents, and would also exhibit lower capture rates. We also hypothesized that fire would decrease capture rates of both groups and that in the 5 years after fire, rodents would be more abundant on burned sites than marsupials. Our data show, however, that population fluctuations in rodents and marsupials were largely synchronous, albeit of greater absolute size in rodents, and only partly explained by antecedent rainfall. While fire initially reduced all mammal populations, postburn areas were preferentially exploited by both groups, with rodents displaying only a weak pattern of prolonged use of burned areas. Since both groups recovered well from drought and wildfire, protection of drought refuges and generation of new habitat through small prescribed burns may benefit both groups. Although dasyurid marsupials have been found previously to show inconsistent responses to rainfall and fire, we conclude that their dynamics may sometimes resemble the "boom" and "bust" cycles that typify rodent populations in Australia's arid interior.