Field enclosure experiments on the technique of poisoning the rabbit, Oryctolagus cuniculus (L.). V. A study of concentration of '1080' in bait material

Abstract

Four 4-acre enclosures were kept stocked with rabbits and used to compare, under different seasonal conditions, the effectiveness of bait, chiefly carrot, poisoned at concentrations of 0.01 %, 0.02 %, or the usual field strength of 0.04 % of sodium fluoroacetate ("1080"). Following free-feeding maximum kills were obtained with carrot bait containing 0.04% or 0.02% "1080" in both summer and winter and with 0.01 % in summer only. Direct feeding with carrot poisoned with 0.01 % "1080" gave a reasonable result during hot summer conditions but was a failure during winter. Carrot containing 0.02% "1080" proved a successful bait when preceded by free-feeding and no increase of bait relative to the amount needed when the poison strength was 0.04% was necessary to achieve high kills. Poisoning is not recommended during wet weather which restricts normal activities of rabbits, and leaching of poison from the bait may possibly lead to the development of bait-shyness as was suspected when carrot containing 0.01 % "1080" was direct fed during wet weather. The risks involved in reducing concentration of "1080" below 0.02% would not be worth any saving in cost. Oat grains proved less reliable bait than carrot in the summer months.