Diurnal pattern of the predatory behaviour of black drongo dicrurus adsimilis (bechstein) on rice field insects

Abstract

Various aspects of predatory behaviour of the black drongo, Dicrurus adsimilis (Bechstein), on rice field insects in continuous rice cropping ecosystem were studied at the experimental farm of the Bangladesh Rice Research Institute in Gazipur during 1992. The black drongo visited rice fields almost throughout the day, except early in the morning and at dusk mainly due to poor light intensity and wet canopy. The insect predatory activities in the rice fields showed a bimodal pattern. The highest activity occurred at 2-3 hours after sunrise with a second peak of activity at 1-2 hours before sunset. Temperature seemed to have regulative influence on the predatory activities of the black drongo in the rice fields. The highest activity was noticed at 24* C . and were markedly reduced above 24° C. Peak incidence of many insect pests, their natural enemies and adults of scavenging insects at the upper rice canopy were synchronized to that of predatory activity of black drongo. It appeared that it consumes a wide range of preys from rice fields.