Ecology of warru (Petrogale lateralis MacDonnell Ranges race) in the Anangu Pitjantjatjara Yankunytjatjara Lands, South Australia.

Australia has one of the world's worst rates of mammal extinctions, accounting for about one third of the mammal species that have become extinct in the world since 1600 (Burbidge and Manly 2002). Most of these documented declines and extinctions have been concentrated towards mammals in the arid-zone of central Australia. In South Australia (SA), one of the arid-zone species that has undergone substantial declines in range and abundance is the black-footed rock-wallaby, Petrogale lateralis (MacDonnell Ranges race). Animals are now restricted to the Anangu Pitjantjatjara Yankunytjatjara (APY) Lands in the state's far north-west, where there remain two known metapopulations. The decline of this race, which is known as 'warru' by Western Desert Indigenous people, is presumed to have been precipitated by introduced predators. However, in order to exclude other potential causes and establish if recovery is feasible, the current project investigated the ecology of warru in the SA APY Lands. In order to make inferences about the habitat and environmental conditions that best facilitate warru persistence, a modelling approach at multiple spatial scales was used. At a landscape scale, warru presence was correlated to geology, slope, soil type and elevation. At a finer scale, fieldwork established that a number of parameters, including aspect, vegetation, rock complexity and refuges' physical characteristics were important determinants of warru presence and use. The work presents the first analysis of P. lateralis habitat requirements. To establish animals' use of this preferred habitat, the thesis provides preliminary data on warru home range and movement patterns. Unfortunately, catastrophic failure of Global Positioning System collars meant that data were limited to those from one adult female in one month. Nevertheless, during this time, the animal had a larger than expected home range and undertook a number of long-range movements, including a sojourn off the hill. These results have implications for management, including predator and fire management strategies. An investigation of the genetic structure of animals in the three largest-known warru colonies indicated that all colonies are genetically diverse, with levels of heterozygosity approximating expected values. All three also exhibited substantial population structuring, with genetic groups correlating to geographic colonies. However, there was also evidence for sub-structuring being present within one of the colonies and for migration occurring into two colonies, with approximately 5% of sampled individuals having mixed ancestry. An analysis of the parentage of offspring indicated that warru have a polygamous mating structure, although one instance of intra- and inter-year monogamy was also established. Population modelling was used to provide an estimate of the sizes of each of the three studied colonies. Combined with recent aerial survey data, these data suggested that there are likely to be fewer than 200 warru remaining in SA. However, all three colonies showed signs conducive to potential recovery, including high average reproductive rates, even sex ratios and high adult survivorship (>75%). Juvenile survival, however, was significantly lower (51%) and positively correlated with winter rainfall, indicating that access to water is important during the drier winter months. The potential for warru recovery was supported by an analysis of warru blood chemistry in both the wild and captive colonies. The latter was established as part of the recovery program and aimed to produce animals for in-situ supplementation and reintroduction. In 2009, when blood samples were taken, warru colonies did not manifest with results that are indicative of population-wide disease. However, the biochemical parameters of animals in one of the in-situ colonies, 'New Well', suggested some level of nutritional and water stress. This suggests that managers could consider providing warru at New Well with supplementary food and water during drought, and/or using fire to promote vegetational diversity. The study presents the first detailed haematological reference values for P. lateralis and potentially, a methodology for other threatened species recovery programs to follow in order to establish the health of their populations. The current results have implications for management of both the in- and ex-situ warru populations. For example, results pertaining to habitat selection can be used to guide selection of appropriate reintroduction sites. Overall, results indicate that although the extant colonies have small population sizes, the animals therein have high reproductive rates, are not suffering the effects of disease and are genetically diverse. The rock-wallabies' polygamous mating strategy is also likely to continue to facilitate this genetic diversity. Furthermore, although warru have specific habitat preferences, they have the capacity to disperse to surrounding available habitat. Overall, this suggests that, given appropriate management, warru recovery is feasible. Some of these data may also be pertinent for management of P. lateralis in the Northern Territory and Western Australia.Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 201

Straddling the divide: den use by brushtail possums (Trichosurus vulpecula) in urban parklands

In Australia, brushtail possums (Trichosurus vulpecula) are declining in natural habitats but have adapted to urban environments so readily that some human residents consider them to be a nuisance. Although this situation represents a conundrum for management, the use of urban habitats by the species remains poorly studied. We conducted our study in six urban parklands, a setting that represents an intermediary between a fully-urban and fully-natural environment. To determine factors that influence the presence of hollows in trees and their use by brushtail possums, physical characteristics of 240 mature trees in six parks in the Adelaide Parklands, South Australia were assessed. To investigate hollow use more comprehensively, 18 possums were radio-tracked. Presence of hollows in trees was a function of tree species and tree size, with hollows formed in both exotic and native species. Tree form and number of hollows were significant predictors of the use of hollow-bearing trees by possums. Use of exotic trees was high, with only 34 % of recorded den trees being native (non-indigenous) species. Radio-tracked individuals were relatively sedentary, with an average daytime denning area of 0.08 ha. While the majority of animals used multiple den sites, all individuals favoured a single den. Use of a variety of anthropogenic structures was high, even when trees were available. On average, sites supported ~1.5 brushtail possums per hollow-bearing tree. A correlation between number of hollows per hectare and possum density (r =0.892, P =0.017) suggests that altering a given area’s density of hollows or anthropogenic structures could influence the density of possums within it

Preliminary spatial behaviour of warru (Petrogale lateralis MacDonnell Ranges race) in the Anangu Pitjantjatjara Yankunytjatjara Lands, South Australia

This study aimed to determine the home range and movement patterns of Petrogale lateralis in the arid-zone Anangu Pitjantjatjara Yankunytjatjara Lands in the north-west of South Australia. Ten Global Positioning System radio collars were attached to animals, with collars programmed to function in 2008–09. Catastrophic collar failure resulted in only 28 days of data, from July 2008, being retrieved from one adult female. During this time, the female occupied a 90% kernel range of 57.9 ha and core (50%) range of 9.3 ha. The animal moved a total of 50.8 km and undertook three journeys of over 1 km. The longest of these was 1.2 km, undertaken in 89 min. The high mobility of the study animal has implications for management, particularly predator baiting and fire management strategies. Future research should assess the validity of these results by increasing sample size and conducting similar work for other arid-zone P. lateralis. The lessons learnt from the current GPS collar deployment may also be of interest to other researchers.Laura Ruykys, Matthew J. Ward, David A. Taggart and William G. Bree

The success of GPS collar deployments on mammals in Australia

Global Positioning System (GPS) wildlife telemetry collars are being used increasingly to understand the movement patterns of wild mammals. However, there are few published studies on which to gauge their general utility and success. This paper highlights issues faced by some of the first researchers to use GPS technology for terrestrial mammal tracking in Australia. Our collated data cover 24 studies where GPS collars were used in 280 deployments on 13 species, including dingoes or other wild dogs (Canis lupus dingo and hybrids), cats (Felis catus), foxes (Vulpes vulpes), kangaroos (Macropus giganteus), koalas (Phascolarctos cinereus), livestock guardian dogs (C. l. familiaris), pademelons (Thylogale billardierii), possums (Trichosurus cunninghami), quolls (Dasyurus geoffroii and D. maculatus), wallabies (Macropus rufogriseus and Petrogale lateralis), and wombats (Vombatus ursinus). Common problems encountered were associated with collar design, the GPS, VHF and timed-release components, and unforseen costs in retrieving and refurbishing collars. We discuss the implications of collar failures for research programs and animal welfare, and suggest how these could be avoided or improved. Our intention is to provide constructive advice so that researchers and manufacturers can make informed decisions about using this technology, and maximise the many benefits of GPS while reducing the risks

A global-scale screening of non-native aquatic organisms to identify potentially invasive species under current and future climate conditions

10.1016/j.scitotenv.2021.147868Science of the Total Environment78814786