Modelling the influence of fire on survival of the northern brown bandicoot (Isoodon macrourus Gould) in the tropical savannas of northern Australia using mark-recapture data

Abstract

Approximately half of the species of Australian bandicoots (family Peramelidae) are extinct, rare or threatened and changed fire regimes in arid and semiarid Australia have been implicated as important agents in their decline. The Northern Brown Bandicoot (Isoodon macrourus Gould) is currently regarded as one of the most common Australian bandicoots, however recent studies at Kapalga, in Kakadu National Park, Northern Territory have shown that this species is prone to large fluctuations in abundance, apparently linked to the occurrence of intense fires. This study examines the influence of four fire management regimes on the survival of the Northern Brown Bandicoot using mark-recapture data obtained during a landscape-scale fire experiment conducted at Kapalga, in Kakadu National Park, Northern Territory from 1989 to 1995. The analysis extends upon earlier work by performing a detailed examination ofbandicoot survival, using information theoretic model selection methods. Results indicate that fire regime is the most important determinant ofbandicoot survival and that the relative importance of other influences such as gender, age, habitat type, time of year and rainfall are minor in comparison. All fire treatments were noted to cause a decline in survival, indicating that none of the management approaches tested could be considered appropriate for this species. Areas left unbumt, or burnt in the early dry season experienced the least overall decline. The bimonthly survival rate in unbumt areas dropped over the six years ofthe study from 0.756 (se 0.0312) in July-August 1989 to 0.5494 (se 0.0505) in March-Aprill995. Similarly, early burnt areas dropped from 0.748 (se 0.042) to 0.589 (se 0.0884). The effects oflate bums on bandicoot survival were quite severe, leading to a marked decline in bimonthly survival rates from 0.783 (se 0.066) to 0.187 (se 0.143) over the same period. The effect of, multiple bums in early and late dry season was the most devastating, causing a rapid and almost complete collapse in bandicoot survival from 0. 782 (se 0.056) to 0.058 (se 0.054). The results demonstrate that this species is most sensitive to frequent and/or intense fires and least affected in areas'~ experiencing low intensity or infrequent fires. The results highlight the importance of adaptive fire management, driven by monitoring of wildlife populations.

Date of Award	Dec 2000
Original language	English