Habitat, microhabitat and calling behaviour of Taudactylus pleione Czechura (Anura: Myobatrachidae), a critically endangered frog from central Queensland, Australia

Examines the habitat, microhabitat and the calling behaviour of the Krombit tinkerfrog, which is a critically endangered myobatrachid frog endemic to the rainforest gullies of Kroombit Tops in south-east Queensland.. Taudactylus pleione (the Kroombit tinkerfrog) is a critically endangered myobatrachid frog endemic to the rainforest gullies of Kroombit Tops, an elevated plateau in southeast Queensland, Australia. Its numbers have declined in recent times, particularly at the higher altitude plateau streams. Efforts to conserve the species, including a proposal to commence captive breeding, are hampered by inadequate knowledge of the species' habitat requirements and conditions required for reproduction. This project investigated the characteristics of occupied rainforest patches and streams, microhabitat and structure of male call sites and influence of climatic variables on male calling activity. Habitat characteristics of rainforestlwet sclerophyll patches and streams used by T. pleione were compared to randomly selected unoccupied patches and streams. Callsites and call-perches used by male T. pleione were compared to available potential callsites and perches. Daily calling activity of male T. pleione was analysed in relation to climatic and other variables. Patches of notophyll rainforest and adjacent wet sclerophyll forest were mapped from aerial photography. The habitat and spatial patterns of ten patches occupied by T pleione and ten randomly selected unoccupied patches were compared. Within these, habitat and microhabitat data were compared for seven occupied and eight unoccupied streams. The habitat of T.pleione can be described as first-order streams at Kroombit Tops originating above 825 m within patches of simple notophyll gully vine forest (Regional Ecosystem 12.12.1) spanning more than 168 m of elevation, that are generally greater than 20 ha in area with an area-perimeter ratio of 73 or higher and a catchment of over 56 ha, no more than 207 m from the nearest occupied patch. Patches of less than 20 ha may be occupied provided they have patch roundness index values of 0.68 or higher. Streams have generally less than 7.9% crevice cover and 'large pebbles' (2.1- 6.0 cm) occurred at a frequency of 30% or more. Data were collected from call-sites used by male T. pleione for advertisement calling and from randomly selected paired locations within the same gully. Occupied call-sites had significantly higher rock and crevice cover, but significantly lower slope and direct summer radiation values. Males were significantly more likely to be found using rockpiles than other call-perch structures available at the site. Preliminary analysis of the acoustic reflectivity of the call-perches used by T. pleione males, based on the density of their component materials, showed they were significantly more reflective than potential call-perches. Daily male T. pleione calling activity was recorded at one escarpment stream over 1,836 days. Associated daily temperature and rainfall data were collected at Kroombit Tops and long-term rainfall and temperature data obtained from Bureau of Meteorology stations within 50 km of the study site. Logistic regression was used to explore the relationship between male calling behaviour at this site and meteorological and astronomical variables. The resultant modelling identified two distinct periods within the calling season: the calling onset and sustained calling periods. The calling onset period model explained 85.9% of cases using five variables describing atmospheric moisture, temperature, rainfall and moon phase. The sustained calling period model explained 77 .8% of cases using three variables describing atmospheric moisture and rainfall. This study has provided the first quantitative data on habitat and microhabitat use by T. pleione and the methodology developed has application for further research on the habitat requirements of the species. Further, this study has greatly increased knowledge of when male T. pleione call and the factors influencing calling. These results can improve the effectiveness of future surveys and monitoring as well as providing a application to any future attempts at translocation or captive breeding of this critically endangered species.