[Trial of a comparative analysis of methods for determining the population density of the black rat]

Studied was the link between the three most commonly applied methods of the deratization practice, aiming to determine the population density of rodents -- the visual method, the untoxic baits method, and the 24-hour/trap method. The three of them were practically tested and approbated in the conditions of an industrial swine-breeding complex, resp., in various productional sections. Data processing was carried out statistically through the methods of the nonparametric and the correlation analysis and the analysis of variance. It was found that the 24-hour/trap method gave the most minimal quantitative characteristics of the rodent population density, while the method making use of untoxic baits was shown to offer the most highly reproducible results. The differences between the average density values obtained by the three methods were essential. On the other hand, the discrepancies in the character of the link between the results obtained with the use of these methods were probably due to the variations in the activity of rodents. This, in turn, was associated with the use of various technologies in the individual sections, the various forms of rodent activity itself as recorded by each single one of the methods, and the varying density in these sections.