Rat Control in cocoa and oil palms and the implications of toxicity on Barn Owls.

The potential secondary toxicity of warfarin, brodifacoum, flocoumafen and bromadiolone to barn owls were studied at their respective commercial field application rates. A four-day poisoned rat of large body weight was grouped with four other healthy rats of lower body weight for prey selection by barn owls in four replicates and the prey selection was terminated when each owl had consumed four poisoned rats. Prey selection was for weaker animals with consumption of four poisoned rats within five to seven days. Variable susceptibility of the owls to the rodenticides was noted with death occurring between, eight to 27 days. Dying owls were weak and showed symptoms of haemorrhage within the foot pads, swollen wings, beaks and nostrials. The findings indicated that all anticoagulatns used for rat control are a potentital risk and secondary hazard to barn owls.