Why do birds practice anting?

Abstract

Anting is the application of ants or “substitutes” of ants by birds to their plumage. The earliest scientific reports concerning this behavior appeared in the early 19th century, but the targeted collection of facts began in the late 1930s. As a result, anting has been recorded (in nature or/and in captivity) on all but one continent for more than 200 bird species of several orders, mostly passerines. “Active” and “passive” antings are usually recognized as the two main types of this procedure. In the active procedure, birds take ants with their bill and directly smear their feathers. Other manifold (several dozen variants) living and nonliving objects are also used for active anting. The birds practicing passive anting visit ant colonies, provoke ants to attack, and allow them to pass through their plumage. For a given type of anting, the procedure consists of stereotypic movements and postures. Ants belonging to the subfamily Formicinae (mostly Formica, Lasius, and Camponotus), which spray or exude formic acid in attack and defense, are predominantly used, whereas Dolichoderinae and Myrmicinae take second and third places, respectively. Although anting can be studied by manipulative experiments with captive birds, the functions of this behavior remain unclear. It has been suggested that anting acts as way of (1) ridding of ectoparasites, (2) feather grooming, (3) decreasing skin irritation during molt, (4) food preparation (removing pungent effluents from ant bodies before eating them), (5) sensory self-stimulation, etc. However, convincing support for any of the hypotheses is still absent.