Prevention of parasite infection in birds: adaptive advantages of anting behaviour

Anting, the application of ants to plumage, has been reported in more than 200 bird species worldwide. The advantage of the peculiar behaviour is hypothesized to be self-treatment against parasites and bacteria because many ant species eject pungent fluids from their exocrine glands, which might help remove ecto- and microparasites from bird’s body. However, this hypothesis has not been well explored. In this study, by using thrush Turdus cardis and two ant species, Lasius spathepus and L. nipponensis , it was tested whether any chemical components on bird’s body surface were altered by anting and whether any ectoparasites were excluded or repelled from the bird’s body. Artificial ant treatments and GC analysis revealed the chemical components on body surface of T. cardis were remarkably altered by anting. Specifically, dendrolasin, a species-specific volatile chemical in the two ants, was added to the body. The anting treatments were significantly effective in removing ectoparasites, louse flies and dipteran insects. Insecticidal effects also were confirmed. Additional experiments showed dendrolasin and some chemical components had directly repellent effects on dipteran insects. It suggests the advantages of anting include the exclusion of harmful dipteran insects and preventive medication for the diseases they introduce, such as avian malaria.