The sensitivity to fluoroacetate (1080) of a number of species of rodents and dasyurids with and without evolutionary exposure to fluoroacetate-bearing vegetation was determined. Rattus fuscipes, and species of Pseudomys from populations with exposure to this vegetation, were particularly tolerant to fluoroacetate. However, the level of tolerance varied among the different populations of each species, depending on the degree to which the toxic plants were present in their microhabitat. The tolerance of the F1 offspring of sensitive R. fuscipes (South Australia) crossed with tolerant conspecifics from Western Australia was mid-range between those of the parental populations. The sensitivity of introduced R. rattus and Mus domesticus from areas with fluoroacetate-producing plants in Western Australia was similar to that reported elsewhere for these rodents. This suggests that their relatively short coexistence with the toxic plants has had little obvious impact on their level of sensitivity to fluoroacetate. The dibbler, Parantechinus apicalis, which coexists with the toxic vegetation, was exceptionally tolerant for a native carnivore/insectivore (LD50 ~35 mg 1080 kg–1). In contrast, however, Phascogale tapoatafa from southern Western Australia was more sensitive to 1080 than was expected, with an estimated LD50 of 7 mg 1080 kg–1. Although the level of tolerance to fluoroacetate was seen to vary depending on the level of exposure of each species/population to fluoroacetate-bearing vegetation, our findings provide further evidence of the evolutionary impact that fluoroacetate-producing plants appear to have had on the genetic composition of indigenous Australian fauna.

Consumption of wild dog baits made from beef crackle by the native mammal species Pseudomys hermanmbwgensis, P. delicatulus and Zyzomys argurus, (Rodentia), and Dasyurus hallucatus, Ningaui timealeyi, Planigale maculata and Sminthopsis macroura (Dasyuridae) was determined in the laboratory. Dasyurus.hal1ucatus and all three rodents were also exposed to baits made from meat. In the presence of alternative food only P. hermannsburgensis and D. hallucatus ate non-toxic wild dog baits. Their projected dose rates if the baits had been poisoned ranged from 25 mgkg to 40 mgkg (P. hermannsburgenris) and 0.32 mgkg to 9.70 mgkg (D. hallucatus). Non-toxic meat bait was also eaten by D. hallucatus and the projected dose rates ranged from 0.18 mgkg to 1.25 mgkg. All the rodents ate toxic meat bait in the presence of alternative food, but showed no symptoms of poisoning.