Giving a Rat's: Acquisition of Baseline Health Data on Native Australian Rodents During a Conservation Translocation

Little is known about the baseline health status of Australia's native rodents. The resultant knowledge gaps are problematic for wildlife translocations, as assessing disease risk is integral to translocation planning and outcomes. A disease risk analysis was conducted for the conservation translocation of native rodents to Dirk Hartog Island, Western Australia. This analysis resulted in a recommendation for a multidisciplinary project to reduce knowledge gaps about the health status of Shark Bay mice (Pseudomys gouldii) and greater-stick-nest rats (Leporillus conditor). Between 2021 and 2022, 130 Shark Bay mice and 122 greater stick-nest rats were translocated to Dirk Hartog Island. Mucosal swabs, whole blood, faeces, and ectoparasites were collected from a subset of these individuals. Molecular testing for four infectious agents was performed, parasite burdens and haematological parameters were examined, and relationships between these variables, health metrics and post-translocation short-term survival were assessed. Necropsies with routine histological assessment on translocation mortalities were performed where feasible. Several indicators of non-infectious factors contributing to morbidity or mortality were found, highlighting the need to iteratively evaluate translocation strategies. There was also an apparent absence of some host-specific parasites, suggesting that active approaches to parasite conservation during translocations should be considered. Molecular evidence of herpesviruses, a paramyxovirus, Bartonella sp., Trypanosoma sp. and Mycoplasma spp. were detected among the translocated animals. Although not associated with morbidity or short-term mortality in this study, the disease potential of these agents is still present. Overall, these results contribute important new data on health baselines for both species, which will assist in informing future conservation planning.