Size matters: extraordinary rodent abundance on an Australian tropical flood plain

Thomas Madsen*, Beata Ujvari, Richard Shine, William Buttemer, Mats Olsson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


Published estimates of the total biomass of natural populations of mammalian herbivores generally have ignored small-bodied taxa (especially, rodents). Including such taxa may dramatically change our understanding of total biomass and energy flow in such systems. Dusky rats (Rattus colletti) are small (up to 210 g) native Australian mammals, and our 5-year mark-recapture study on a tropical flood plain (Adelaide River, Northern Territory) revealed that rat biomass can reach extraordinary levels (up to 4.7 t km-2). Because their small body size results in high mass-specific metabolic rates, a given biomass of rodents has a several-fold higher total energy requirement than the same mass of large-bodied herbivores. Accordingly, during some years dusky rat biomass can be double that estimated for large herbivores on the world's most productive savannas in eastern and southern Africa. The huge rodent biomass strongly suggests that the Adelaide River flood plain must be an incredibly productive habitat. Considering the immense biological importance of these productive ecosystems, flood plain conservation must be placed high on the priority list of habitats that require immediate protection.

Original languageEnglish
Pages (from-to)361-365
Number of pages5
JournalAustral Ecology
Issue number3
Publication statusPublished - May 2006
Externally publishedYes


  • Australia
  • biomass
  • dusky rat
  • flood plain
  • small herbivores


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