Association of drongos with myna flocks: Are drongos benefitted.

ABSTRACT

Common myna (Acridotherus tristis) and jungle myna (Acridotherus fuscus) forage in pure and mixed flocks of various sizes in fallow lands. These flocks were often found associated with drongos that forage individually on the insects herded out by the movements of the flocking myna. We report here the benefits and costs of such association to drongos and mynas. Drongos had a tendency to associate with larger (> 21) than smaller (<20) flocks irrespective of the species composition of the flocks. Drongos associated with larger flocks showed increased foraging trips and harvested more insects in a given time than those that were either isolated or were associated with small flocks. The food range of drongos and mynas differed significantly indicating that they do not compete with each other. Thus our results indicate that drongos are benefitted by this association; however this association neither benefits nor costs to the mynas. The association between the drongos and mynas therefore appears to be commensalistic.