Ecology and conservation of the northern hopping-mouse and sympatric vertebrates of Groote Eylandt

Abstract

Effective monitoring is a critical component of wildlife management. The conservation of the enigmatic northern hopping-mouse (Notomys aquilo) has been impeded by poor understanding of the species' ecology; an issue compounded by the lack of appropriate survey methods. Within a genus of largely arid-dwelling rodents, N. aquilo is the only extant species in Australia's northern, monsoonal tropics where it is likely restricted to Groote Eylandt and a small area on the adjacent mainland. Surveys for N. aquilo have traditionally involved recording the location and abundance of indirect signs, as the species is trap-shy towards box-style traps, such as Elliott traps. One of the most important signs is the 'spoil heap' left by the construction of hopping-mouse burrows. Recent surveys for N. aquilo have relied almost entirely upon the identification of spoil heaps; however, the effectiveness of these methods has been questioned. This study aimed to fill key gaps in this knowledge by: (1) evaluating the effectiveness of spoil heap surveys for determining the presence and abundance of N. aquilo; (2) developing more-reliable survey methods for N. aquilo and sympatric vertebrates; and (3) describing the general ecology of N. aquilo with views to its conservation on Groote Eylandt.A novel use of video camera traps allowed the recording of burrow construction by N. aquilo. This confirmed that conspicuous spoil heaps are associated with N. aquilo burrows and these remain visible many months after construction is complete. However, further monitoring confirmed that the sympatric delicate mouse (Pseudomys delicatulus) constructs similar burrows to N. aquilo on Groote Eylandt and spoil heaps made by the two species cannot reliably be differentiated in field surveys. These results emphasised the pressing need for unambiguous survey methods for N. aquilo and suggested that the abundance of the species has potentially been overestimated in the past.Camera trapping and pitfall trapping were identified as possible alternative methods for monitoring N. aquilo. An experiment was conducted to determine if the rate of detection of N. aquilo and other mammals could be increased by the use of a particular bait at camera trap stations. Detection rates for N. aquilo were low and no significant effect of bait type was found for this species. However, sesame oil resulted in the equal highest number of N. aquilo detections, had better longevity, and attracted fewer non-target bandicoots than other baits trialled and, therefore, may be the most useful bait for standardised camera trapping surveys targeting N. aquilo. Trapping with three different sized pitfall traps was conducted in two different habitats over two years. The results from this study demonstrate that general fauna surveys may benefit from the use of a deep, wide pitfall trap that is effective in capturing herpetofauna as well as rare mammals such as N. aquilo. ivThe general ecology of N. aquilo was described using pitfall trapping and radio-tracking. It was found that N. a...

Behavioral Responses of Wild Rodents to Owl Calls in an Austral Temperate Forest

“…At each foraging station, we organized video recordings by "events" to distinguish between independent detections of each species. An event was considered as a video or several videos of the same species within a five-minute interval [42]. Therefore, we grouped behavioral analyses for each event, and we summed the time dedicated to each behavior within each event.…”