An experimental evaluation of lamb predaton in response to fox (Vulpes vulpes) control in south-eastern Australia

Fox predation has long been suspected as a major cause of lamb death in southern Australia. The response of farmers has been to poison foxes using sodium monofluoroacetate (compound 1080). This has become more widespread in recent years due to a number of factors including the reduced returns from sale of skins which has made shooting foxes unprofitable. In a replicated experiment we investigated the effect of fox control on lamb survival. Fox baiting was implemented at three levels; no baiting, baiting once a year before lambing (the recommended practice), and baiting three times a year. This was carried out on sheep properties with ultrasounded flocks over three years. The experiment was conducted in central New South Wales, Australia, in an area where wild dogs and native dingoes had been eradicated. Foxes, an introduced species, were the major mammalian predators of lambs in the district, as estimated from previous post-mortems of lamb carcasses. No significant difference was detected in lambing, as measured by the number of lambs per ewe at lamb marking 8 to 10 weeks after birth, however, there was a significant effect of fox control on the number of healthy lambs killed by foxes assessed by lamb post-mortems. The possible reasons for this result are discussed including features of the experimental design and the level of replication