Read the Spanish translation: Conservación en el Interior
Abstract
Arid Recovery is a unique conservation initiative based in the south Australian outback and is primarily supported by BHP Billiton (Olympic Dam), South Australian Department for Environment and Heritage, The University of Adelaide, and the local community.1 A focal point of this initiative is the feral-proof fenced Arid Recovery Reserve which covers a total area of 123 km2, of which 60 km2 is free from feral cats, foxes, and rabbits. These species were completely removed from the reserve in 2001 by a combination of 1080 poisoning, warren fumigation, trapping, and shooting.1 The removal of these feral species has allowed regeneration of native plants and re-establishment of native mammal populations within the reserve. Locally extinct, threatened mammal species, including the greater stick-nest rat (Leporillus conditor), burrowing bettong (Bettongia lesueur), greater bilby (Macrotis lagotis) and western-barred bandicoot (Perameles bougainville), have also been successfully reintroduced into the reserve. There is ongoing control and removal of cats and foxes in a 200 km2 unfenced area adjacent to the reserve, so that wild populations of bilbies can be established in this area.
There are multiple ongoing monitoring projects conducted within and surrounding the Arid Recovery Reserve. Populations of the burrowing bettongs, greater bilbies, greater stick-nest rats, and western barred bandicoots are monitored through quarterly track transects and annual cage trapping. Tracks are swept the day before counting with a chain dragged behind a quad bike. All tracks that cross over this dragged line are then counted the following day. Any reintroduced species trapped has body weight, sex, reproductive status, and pes length recorded and a unique identification number given to the animal either through microchipping or ear tagging. Tail width is also recorded for burrowing bettongs. All trap data are entered into a database. Bilby and bettong burrows are monitored annually for activity, size, and co-occupants. Similarly, greater stick-nest rat nests are monitored twice a year. The number of tracks and presence of fresh scats are just some parameters used to determine the activity of each burrow and nest. The successful establishment of these thriving populations of all four reintroduced species has been confirmed by these regular monitoring methods.
Research is also a large component of Arid Recovery. Current investigations include the role of dingoes in controlling cat and fox numbers by studying the interactions among dingoes, cats, and foxes in a 37 km2 fenced enclosure using GPS collars on these species. A one-way gate is also being designed and trialed to allow greater bilbies and burrowing bettongs to naturally disperse into areas where they are currently not inhabiting. This could overcome the unnatural barrier to dispersal formed by the fence that can lead to overstocking. Different gate designs are being tested on feral cats to ensure that they cannot gain entry. There are also more projects planned to help understand the ecology and health status of the reintroduced species. The current research priorities include comparing founder stock genetics of reintroduced species with that of the current population to investigate the genetic diversity within these species. Samples have been collected from the ear of each species during regular trap sessions, and these have been stored for genetic testing. Another research priority involves investigation of the impact of mining on the reintroduced species. This is important as the Arid Recovery Reserve is located near the BHP Billiton Olympic Dam mine site, which is currently the largest underground mine in the southern hemisphere.2 Olympic Dam mines uranium, copper, gold, and silver and while there is no evidence to suggest that the reintroduced species are showing any signs of heavy metal toxicity, it is important to investigate if proximity to the mine-site is a threat to the long-term survival of these species and establish some baseline data before the planned expansion of the Olympic Dam mine.
The main objectives of the project investigating impacts of mining on the reintroduced species included a literature review on heavy metal toxicity in mammals and identification of the main clinical signs, both immediate and long-term, associated with exposure to different levels of heavy metal contamination. The literature review revealed that signs of heavy metal toxicity reported in terrestrial mammals include decreased hematocrit and hemoglobin levels, pathologic changes in red blood cell morphology, changes in blood urea/creatinine levels, increased metallothionein levels, changes in liver enzymes, decreased body and/or organ weights, histopathologic changes in organs, and increased frequency of chromosomal aberrations. The literature review was then used to develop a pilot study involving blood collection from the burrowing bettongs and performing the most cost-effective tests such as morphologic evaluation of blood smears using light microscopy. The pilot study enabled development of a protocol for blood collection from the lateral tail vein of burrowing bettongs. Blood smears examined from the pilot study showed no significant abnormalities in red blood cell morphology and white blood cell differential counts. The study has also revealed the lack of research to establish normal reference ranges for hematologic values in burrowing bettongs. The pilot study will form the basis of further investigations into heavy metal burdens in reintroduced fauna within the reserve as well as help to establish a baseline database.
Acknowledgments
The authors thank Arid Recovery and its partners for the opportunity to participate in this project, as well as Roxby Downs Veterinary Clinic for providing the materials required for blood collection and testing. Research was conducted under ethics approval number (35/2009-M2).
Literature Cited
1. Arid Recovery. 2010. Arid Recovery Official Website. http://www.aridrecovery.org.au.
2. BHP Billiton. 2010. BHP Billiton Official Website. http://www.bhpbilliton.com/bb/ourBusinesses/baseMetals/olympicDam.jsp.