IOPHENOXIC ACID AS A QUANTITATIVE BAIT MARKER FOR FOXES

The potential of iophenoxic acid as a quantitative bait marker for red foxes was investigated. Groups of adult foxes were administered doses of either 20, 40 or 60 mg, representing one, two or three baits. Base line concentrations of plasma iodine were compared with samples collec ted one, three, six and ten weeks after exposure. Plasma iodine levels were elevated by 7-18 times base-line estimates after six weeks and h ad returned to pre-treatment levels in approximately half the foxes by ten weeks. Application of regression analyses provided a relationship that could be used to estimate the number of baits eaten from post-ex posure plasma iodine levels and the number of weeks after bait was off ered.