Conservative population declines of 73% were recorded in three independent feral pig populations in Welford National Park, Queensland, when PIGOUT ® baits containing 72 mg of sodium fluoroacetate were used in a baiting program following prefeeding. Declines were measured using a prebaiting population census with remote cameras, followed by carcass recovery. The knockdown of susceptible feral pigs may have been higher than this, since any carcasses not recovered reduced the recorded efficacy. In addition, feral pigs know to have left the baiting area after trapping and telemetry-tagging, and subsequently not exposed to toxic baits, were included in the analysis. The use of remote cameras and carcass recovery appears to be a relatively accurate means of recording localised declines in feral pig populations. This method is applicable only when carcass recovery is possible, such as in open areas in the semi-arid rangelands. A decline of 86% of radio-tagged feral pigs attending bait stations was also recorded. Camera observations revealed no non-target consumption of baits. Measurement of sodium fluoroacetate-contaminated tissues from feral pigs showed that residues were too low to present a significant risk to recorded scavenging animals in the area. Some feral pigs vomited before death, with vomitus containing sodium fluoroacetate poison at high concentrations. No vomitus was consumed by non-target species. Almost all feral pigs were killed relatively rapidly after ingestion of sodium fluoroacetate and the signs observed in a small number of poisoned feral pigs did not indicate a significant welfare concern.

Summary1. This paper reports on the behavioural effects of surgical sterilization when used to simulate immunocontraception in free-ranging female foxes Vulpes vulpes . 2. During 3 years of trapping, 348 male and female foxes were fitted with transmitters in two treatment (females sterilized) and two untreated areas. 3. Radio-tracking indicated that sterile and fertile vixens maintained similar-sized territories during the breeding season, but that sterile females were possibly more likely to share their territories with each other. 4. There were no consistent differences in survival or dispersal between sterile and fertile females. 5. Outcomes from the study suggest that immunocontraception in free-living foxes is feasible.

This study describes temporal, spatial and individual variation in the diet of 255 red foxes (Vulpes vulpes) collected from agricultural land in central New South Wales from July 1994 to November 1996. Rabbits (Oryctolagus cuniculus), sheep (Ovis aries), eastern grey kangaroos (Macropus giganteus) and invertebrates were the most important food items overall. Significant seasonal variations, and sex and age differences between foxes occurred in the consumption of some food types. Some temporal synchrony was also evident, with different individuals often eating similar foods on the same night. This may have been related to moonlight. On full moon nights, foxes ate rabbits and small mammals significantly less often than during other moon phases. The management implications of variation in diet are discussed.

The successful ‘Judas’ goat technique has been adapted for use with feral pigs. The ‘Judas’ goat technique involves releasing radio-collared goats into a control area and, after a sufficient period to allow them to join other goats, tracking them down and culling the other individuals associated with them. Trials with the technique on feral pigs in Namadgi National Park, ACT, indicated that it worked best with sows captured in the same area. Each of these sows established contact with 1–8 other pigs in the area within 1–7 days of release and was located with at least one other pig on 67–100% of occasions. In contrast, sows and boars from outside the study area took longer to come into contact with ‘local’ pigs and associated with them much less frequently. A subsequent control exercise in Namadgi, using ‘Judas’ pigs to indicate where to lay warfarin baits from a helicopter, resulted in a 75% reduction in the low-density population still present after a larger control exercise two years earlier. Since then, the technique has been used to eradicate a small colony of feral pigs in central Australia and is proving successful for control of feral pigs and other ungulates in other parts of Australia and New Zealand.

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