Surveys of small and medium sized mammals in northern Queensland with emphasis on improving survey methods for detecting low density populations

Abstract

The primary aim of this thesis was to investigate the decline of small and medium sized mammals in northern Queensland by: determining the population status of the endangered Bramble Cay melomys, Melomys rubicola and investigate the cause of any decline; collating all historical mammal relative abundance data (mammals ≤ The three surveys undertaken on Bramble Cay failed to detect any Bramble Cay melomys. The island had experienced a recent, severe reduction in vegetation, which is the primary food resource for the Bramble Cay melomys. Herbaceous cover on the cay decreased from 2.16 ha in 2004 to 0.065 ha in March 2014 before recovering somewhat to 0.19 ha in August-September 2014. For the NG region, combined datasets from 430 1-ha plots represented sampling efforts totalling 3,316 cage trap nights; 34,480 Elliot trap nights; 6,270 pitfall trap nights and 298.5 hours of spotlighting. A total of 461 individuals, from 24 species were captured. Of the 430 plots, 261 failed to detect any mammals. The majority of the records in the Einasleigh Uplands bioregion were restricted to Blackbraes National Park and a neighbouring property where 80.9% of the plots recorded mammals. Twenty-six (21 native and 5 introduced) mammal species were detected during the surveys in 2015-2016. Of the 732 captures that could be confidently identified, 85.1% (623 camera events from 20 species) were detected by camera trapping, and 14.9% (109 captures from 15 species) were captured using the standardised plot survey method. Camera traps were significantly more effective than the standard plot survey in detecting the dingo, Canis lupus dingo, pig Sus scrofa, northern quoll, Dasyurus hallucatus, northern brown bandicoot, Isoodon macrourus and short-beaked echidna, Tachyglossus aculeatus. The grassland melomys, Melomys burtoni, was detected on significantly more plots using the traditional survey method. Sampling efforts for the bait trial at MTSWRNR totalled 2,776 camera trap nights (CTN) with 16,531 images and 1269 events collected. A total of 39 species were identified in these events including 13 mammal species. Bait type significantly affected mean camera events for the agile wallaby, Notamacropus agilis (P = 0.039). Agile wallabies visited the sesame oil bait stations 1.5 times more than peanut wax bait (P = 0.030). Bait type significantly affected mean species richness of small native mammal species (P = 0.004). Peanut butter bait attracted 1.7 times more small native mammal species than sesame oil (P = 0.003). There was a significant association between bait type and mould (P = <0.001). Sesame oil bait had the best longevity with no mould present on any of the baits at the end of each trial period. Declaration by author This thesis is composed of my original work, and contains no material previously published or written by another person except where due reference has been made in the text. I have clearly stated the contribution by others to jointly-authored works that I have included in my thesis. I have clearly stated the contribution ...