Harvestmen as predators of bird nestlings

We report the first confirmed cases of harvestmen (Opiliones) feeding upon live vertebrates. In June and July of 2007, in two independent studies of the ecology of Swainson's warblers (Limnothlypis swainsonii Audubon) in Arkansas and North Carolina, we recorded predation of nestlings at two separate nests by harvestmen. Both events were nocturnal, involved relatively young and dependent nestlings, and contributed to or resulted in the death of one or more nestlings. One event involved a group of at least four harvestmen with one to four individuals feeding upon a brown-headed cowbird (Molothrus ater) nestling at one time, and the other involved up to two harvestmen present at the nest, but only one individual fed upon the two Swainson's warbler nestlings.