Status of a threatened rodent population in monsoonal northern Australia

Context Small mammals of northern Australian tropical savanna continue to face severe declines. The brush-tailed rabbit-rat (Conilurus penicillatus) is among the most threatened mammals, having undergone a dramatic range contraction to mesic coastal areas and islands. The Cobourg Peninsula supports what is likely to be the last rabbit-rat population on the Northern Territory mainland. Concerningly, there has been limited targeted and systematic monitoring of the Cobourg Peninsula population in the past decade, despite the high forecasted extinction risk and steep declines having also been recently detected in a neighbouring refuge population. Aims This study broadly aimed to investigate the spatial distribution of brush-tailed rabbit-rats on the Cobourg Peninsula and assess whether variation in the species’ abundance was associated with habitat features and fire metrics. Methods A baited camera survey across 70 sites in Garig Gunak Barlu National Park on the Cobourg Peninsula was conducted in the late dry season of 2025. Royle–Nichols occupancy modelling was used to estimate the species’ current distribution and investigate correlates of relative abundance derived from both remotely-sensed datasets and field-based habitat assessments. Key results Rabbit-rats had a naïve occupancy of 93%, which is currently the highest reported for any population monitored using remote cameras. However, rabbit-rat relative abundance was patchy across the peninsula, influenced by woody plant species composition and increased with time since fire. Conclusions The Cobourg Peninsula continues to remain one of the last strongholds for the brush-tailed rabbit-rat. Implications Despite no apparent decline in occupancy within the study area, management should not become complacent given that declines can occur without any appreciable change in the threat landscape. Ideally, a species-wide monitoring program is established to ascertain trends in occupancy, particularly given that populations in similar environments appear to be declining at varying rates. This will further assist in assessing the effectiveness of certain management responses.