New Zealand Journal of Ecology (1986) 9: 123- 136

Rabbit (Oryctolagus cuniculus) Control with a Single Application of 50 ppm Brodifacoum Cereal Baits

Research Article
J. M. Williams  
J. Bell  
W. D. Ross  
T. M. Broad  
  1. Agricultural Research Division, Ministry of Agriculture and Fisheries, P.O. Box 24, Lincoln, New Zealand

The relationships between an index of rabbit density (number spotlighted), bait application rate and control effectiveness of a single application of a highly acceptable cereal bait (1250 baits/kg), containing 50 ppm brodifacoum, were investigated. The impact of this control on non-target species was also evaluated.
Bait application rates >500 baits per spotlighted rabbit killed 97-100%, while rates averaging <300 baits/rabbit killed <65%. Provided application rates did not exceed about 800 baits/rabbit, 80% were consumed by day 3 to 4, so few remained to pose risks to domestic livestock. Most rabbits died between the fourth and eighth day with the majority of deaths occurring in burrows or under scrub, thus reducing access to avian predators.
The large number of baits eaten resulted in brodifacoum residues in the rabbits (mean 4.4 mg/kg in livers). This contributed to the few observed non-target deaths of avian and mammalian rabbit predators. However there appeared to be no long-term impact on rabbit predator-prey relationships in the study area as a result of a single application of brodifacoum baits.