Anting

When we say a bird is anting, we mean that it is on the ground or on a twig with one or both wings half-spread and with its tail drawn under the body. In this unusual attitude it can be seen picking up ants with its bill and rubbing its head among the undersides of the wings and – or – into the base of the tail.

When anting the Jay does not pick up ants in the bill although it makes the same movements of the head as species which do. The wings are (at high intensity) spread quite widely and thrust forward like a canopy in front of the anting bird. Usually both wings are thrust forward together. I have seen a great number of both wild and captive Jays anting […]

Blue jays are not just smart, they're also quirky. They are frequently given as exemplars of a bird behavior known as "anting," in which the bird lies down on an anthill with wings and tail spread and entices ants to swarm over it. Anting birds often grasp an ant in their beak, crush it, and wipe it under their wings, and over and through their feathers, and then sometimes eat them. […] The purpose of anting is still debated. It has been hypothesized that the formic acid in ants, when applied to the feathers, helps to control feather lice and other parasites, but the experimental evidence about this is mixed. It has also been suggested that birds are simply wiping the acid off so that the ants will taste better when they subsequently eat them. Others have suggested that anting is pleasurable, like a kind of bird catnip.

Anting. A behavior in which the fluids from ants, notably formic acid, are applied to the plumage and possibly the skin. There are two basic types of the behavior: active anting, in which the bird anoints its plumage with the bill, and passive anting, in which the bird allows ants to invade and anoint the plumage. […] Some individuals of these species, in unnatural situations such as in captivity, perform active anting with burning matches and cigarette smoke, moth balls, hair tonic, mustard, citrus fruits, numerous insects other than ants, and other substitutes. What causes anting and what purpose or purposes it serves, if any, need investigation.