Abstract
Field tests of rat control were carried out in residental areas to know a pattern in consumption of baits with warfarin and thallium sulfate and also to know the estimating method of the rat population exposed to the baits by daily consumption of them. The dominant species inhabiting in these areas were Rattus norvegicus and Rattus rattus. It was observed that about one third of the exposed population of the rats in the experimental area fed warfarin baits on the first day, about two third on the second day and the maximum consumption was shown on the third day. Thereafter, feeding rate decreased. It was thought that three day intake of 0.03% warfarin bait was enough to kill almost all of the rats. If the population is very large of infiltration in rat from outside into the experimental area might be expected, the pattern of the bait consumption should be complicated. When rats were exposed to thallium sulfate baits, 33-44% of the total population would take the baits every day. In this case, one intake of the baits is fatal to rats. In both cases, rat population exposed to the baits could be estimated by the same method as the removal method by traps.
