 The antbirds have a parasitic relationship with "Eciton burchellii" which inflicts a cost that is proportional to the number of birds in the flock.This imposes a selective pressure on the colonies, as the arthropods collected from these raids represent nearly half of the food consumed by the ants.To counter-act the antbird's kleptoparasitism, large prey items have been observed to be dragged under the leaf litter before being processed.