Comparison of effectiveness of introduced barn owls, Tyto javanica javanica, and rodenticide treatments on rat control in oil palm plantations.

In Peninsular Malaysia, barn owls (Tyto javanica javanica) have been utilized as biological control of rats since the 1960s. In this study, the impact of introduced barn owls on rat populations in an oil palm plantation in Sabah, Malaysia, were studied. There were three treatment areas in this study: T1 (barn owl area) was an oil palm plot where no rodenticides were applied and rat control relied solely on predation of the introduced barn owls, T2 was an oil palm plot where one fixed baiting campaign was carried out per year, and T3 was an oil palm plot where two fixed baiting campaigns were carried out per year. Rat abundance and fresh fruit bunch (FFB) damage were assessed monthly throughout the four-year study period. The dominant species at all treatment areas was the House rat, Rattus rattus diardii. Both rat abundance and FFB damage were higher in the first year of study at all three treatment areas. FFB damage was lowest at T3 compared to the other two treatment areas throughout the entire study period, probably due to the intensive baiting carried out at T3. FFB damage at T1 was comparable to FFB damage at T2 (with the exception of the first year of study). Additionally, FFB damage at T1 after the first year was frequently below the 5% FFB damage threshold level. The results of this study indicate that introduced barn owl control of rat pests was sufficient for at least three years and perhaps more. [ABSTRACT FROM AUTHOR]