Palatability of bird repellents to Rattus norvegicus

The palatability to captive, mostly laboratory-bred, Norway rats (Rattus no rvegicus) of cereal-based baits containing 0.02 g kg(-1) brodlifacoum, with and without bird-repellent additives, was compared in a no-choice experime ntal design. Methyl anthranilate (25 g kg(-1)), dimethyl anthranilate (25 g kg(-1)) and cinnamamide (2.5 g kg(-1)) reduced bait consumption by the rat s, but all except one rat ate enough bait to receive a lethal dose. Cinnama mide (1 g kg(-1)), ortho-aminoacetophenone (0.1 g kg(-1)) and tannic acid ( 20 g kg(-1)) did not reduce bait consumption and all rats died after eating baits. The concentration of cinnamamide palatable to rats has only a low a nd short-lived repellency to birds, so it does not warrant further investig ation. However, ortho-aminoacetophenone and tannic acid should now be field -tested for palatability to all three rat species in New Zealand and for re pellency to native New Zealand birds. (C) 2001 Society of Chemical Industry.