Implications of prefeeding for the development of bait aversions in brushtail possums (Trichosurus vulpecula)

Development of aversions, or learned ‘bait-shyness’, in frequently poisoned possum (Trichosurus vulpecula) populations is becoming increasingly detrimental to the efficacy of pest-control operations in New Zealand. This experiment aimed to identify the effects of prefeeding, a common management procedure, on the subsequent development of aversions in possums. Wild possums (n = 96) were captured and acclimatised, then allocated to one of three treatments groups that for seven days received either (i) no prefeed, (ii) plain RS5 cereal baits, or (iii) green-dyed and cinnamon-lured RS5 cereal baits. The possums were then offered a standard green-dyed and cinnamon-lured RS5 bait that contained a sublethal dose (0.4 mg kg-1) of the toxin sodium monofluoroacetate (1080). The possums were tested for development of an aversion towards a toxic RS5 1080 bait, a prefeed bait, and a prefeed bait containing an alternative toxin, brodifacoum.

Most (96%) of the non-prefed possums became averse to the 1080 bait after two exposures, compared with only 55% and 9% of the two prefed groups. Similarly, 90% and 92% of the non-prefed possums were averse to prefeed and brodifacoum baits, respectively, compared with 8% and 14% of the prefed possums. This suggests that pest managers can reduce the risk of ‘bait shyness’ by prefeeding. A further advantage of prefeeding is that if poison shyness develops, use of an alternative toxin such as brodifacoum in the original bait base may still be successful.

Author Moss, Z. N., O'Connor, C. E. and Hickling, G. J.
Year 1998
Secondary title Wildlife Research
Volume 25
Pages 133-138
Control method Baiting
Region NZ