Where there’s smoke, there’s cats: long-unburnt habitat is crucial to mitigating the impacts of cats on the Ngarlgumirdi, greater bilby (Macrotis lagotis)

Abstract

Context

The decline of the greater bilby (Macrotis lagotis), or Ngarlgumirdi (Yawuru), like other critical-weight range Australian mammals, is believed to be primarily due to the synergetic impacts of predation by feral cats and foxes, habitat disturbance caused by large introduced herbivores, and increases in the frequency and intensity of wildfires. Although it has been demonstrated that low-intensity prescribed burning mosaics in some habitats have the potential to benefit mammals, including Ngarlgumirdi, by creating habitat with sufficient vegetation cover, the contributions of specific fire-mosaic attributes to Ngarlgumirdi persistence remain unclear.

Aims

To elucidate the impacts of fire-mosaic attributes on the occupancy of Ngarlgumirdi on the Dampier Peninsula.

Methods

We used 2-ha sign-plot data collected by four Indigenous Ranger groups, in combination with 20 years of satellite-derived fire-history information to investigate the multiscale impacts of fire attributes on Ngarlgumirdi and feral cats (Felis catus) on the Dampier Peninsula in the West Kimberley region, a large, unfenced landscape in the most fire-prone section of the Ngarlgumirdi’s current range.

Key results

We found that Ngarlgumirdi was more common in areas that had a higher proportion of habitat that had not burnt for at least 3 years, whereas feral cats were less prevalent in these areas. Similarly, Ngarlgumirdi was less likely to occur in landscapes affected by frequent fires, whereas cats were more common there.

Conclusions

Our findings have highlighted the importance of decreasing fire frequency and increasing the extent of long-unburnt habitats (>3 years) for preserving Ngarlgumirdi on the Dampier Peninsula and mitigating ecological damage inflicted by feral cats. Findings were consistent across spatial scales (1-, 3-, 5- and 10-km radius from each monitoring site).

Implications

These results have demonstrated the potential of fire management to increase native species resilience in the absence of direct feral cat control methods. Further, they support a recent cross-tenure initiative led by Traditional Owners to implement fire management that aims to reduce large, frequent high-severity wildfires and increase areas of long-unburnt vegetation on the Dampier Peninsula.